What to Do When Ventilation Clogs Occur

What to Do When Ventilation Clogs Occur

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Identifying Signs of a Ventilation Clog



Ventilation systems are crucial for maintaining indoor air quality and ensuring the efficient operation of heating, ventilation, and air conditioning (HVAC) units. Regular HVAC Repair helps prevent unexpected system failures and costly repairs Ductwork repair to ensure your geothermal heat pump is working properly. However, like any other mechanical system, they are susceptible to issues such as clogs. Identifying signs of a ventilation clog early can prevent severe consequences like increased energy costs, equipment damage, or even health risks. Understanding these signs empowers homeowners and facility managers to take timely action.

One of the most apparent signs of a ventilation clog is reduced airflow from vents. If you notice that the volume of air coming through your registers seems diminished, it could indicate a blockage somewhere within the ductwork. This obstruction forces your HVAC system to work harder to maintain desired temperatures, often resulting in uneven heating or cooling throughout your space.

An unexplained increase in energy bills is another telltale sign of a clogged ventilation system. When ducts are obstructed, HVAC systems consume more energy to compensate for the restricted airflow. This inefficiency translates into higher utility bills without any change in consumption habits or external factors influencing energy use.

Dust accumulation around vents or an unusual amount of dust settling on furniture can also suggest a clog in your ventilation system. Clogged ducts often lead to debris buildup which eventually finds its way into living spaces. If routine cleaning does not seem to reduce dust levels significantly, inspecting your ducts for blockages might be necessary.

Unpleasant odors emanating from vents can further signal problems within your ductwork. These smells may result from mold growth due to moisture trapped by obstructions or decomposing matter caught within the ducts themselves. Such conditions not only affect indoor air quality but also pose potential health hazards if left unaddressed.

Noise is another indicator; unusual sounds such as whistling or banging when the HVAC unit operates might mean that something is obstructing normal airflow through the ducts. While some noise during operation is typical, especially with older systems, sudden changes should prompt an inspection.

Once you identify potential signs of a ventilation clog, addressing them promptly is crucial for restoring optimal function and avoiding further complications. Begin by visually inspecting accessible parts of your ductwork and removing any visible debris around grilles and registers using appropriate tools like vacuum cleaners with hose attachments designed for this purpose.

For more complex issues deeper within the system that require specialized knowledge or equipment beyond basic home maintenance capabilities-such as cleaning deep-seated clogs near central components-it's advisable to consult professional HVAC technicians who have experience handling these situations safely and effectively.

In summary, recognizing early warning signals indicative of clogged ventilation helps mitigate adverse effects on both comfort levels indoors and financial aspects related to running inefficient systems over time-all while safeguarding overall well-being by reducing exposure risks linked directly back towards compromised environmental conditions fostered under neglected upkeep scenarios alike! Taking proactive steps ensures long-term performance sustainability alongside peace-of-mind assurances knowing everything remains functioning optimally behind-the-scenes where unseen otherwise until tangible evidence surfaces demanding attention accordingly addressed thereafter via informed decisions guided toward resolution outcomes beneficially achieved ultimately satisfying everyone involved satisfactorily results-wise conclusively speaking indeed!

Common Causes of Ventilation Blockages



Ventilation systems are critical components in both residential and commercial buildings, ensuring the circulation of fresh air, maintaining indoor air quality, and regulating temperature. However, like any mechanical system, they can encounter issues over time. One prevalent problem is ventilation blockages, which can significantly affect the efficiency of a building's heating, ventilation, and air conditioning (HVAC) system. Understanding the common causes of these blockages and knowing what to do when they occur can help maintain a comfortable and healthy environment.

One of the most frequent causes of ventilation blockages is the accumulation of dust and debris. Over time, dust particles from various sources-such as outdoor pollution or indoor activities-can accumulate within ductwork. This build-up reduces airflow efficiency and puts additional strain on HVAC systems. Regular maintenance practices such as changing filters frequently and scheduling professional cleanings at least once a year can prevent significant dust-related blockages.

Another common cause is pest infestation. Small animals like birds, rodents, or insects can find their way into ventilation ducts seeking shelter or warmth. Their presence not only obstructs airflow but also poses health risks due to potential contamination from droppings or nesting materials. To mitigate this risk, it's crucial to inspect duct openings regularly for signs of animal intrusion and seal any entry points promptly.

Mold growth is another issue that often leads to blockage in vents. Mold thrives in damp environments where moisture accumulates-a situation that may arise from leaks or condensation within the ductwork itself. The presence of mold not only blocks airflow but also releases spores into the living spaces that could lead to respiratory problems for occupants. Addressing this involves identifying sources of moisture ingress-perhaps through insulation repairs or dehumidification-and ensuring regular inspections for early detection.

In some cases, improper installation or design flaws contribute to clogging issues. Ducts that are too narrow for proper airflow or have excessive bends can create choke points where obstructions easily form. When designing new systems or renovating old ones, it's essential to work with experienced HVAC professionals who understand how to optimize duct layout for maximum efficiency.

When faced with a clogged ventilation system, prompt action is necessary to restore normal function and prevent further complications such as increased energy bills due to overworked systems trying harder than necessary to achieve desired temperatures.

First steps include attempting simple DIY fixes: check accessible parts like grilles for visible obstructions you might remove manually; replace dirty filters immediately; clear away furniture blocking return vents which impede circulation throughout rooms served by those outlets.

If these measures don't resolve issues-or if there's suspicion about more serious underlying problems-it's advisable then contact qualified technicians equipped handle comprehensive diagnostics followed through targeted interventions tailored specific circumstances encountered during assessments conducted onsite premises involved tackling challenges posed particular setup installations under review scrutiny process engaged therein determining optimal pathways forward achieving satisfactory outcomes intended addressing concerns raised initially prompting inquiries made originally regarding difficulties being faced encountered operationally speaking situational context considered holistically overall perspective taken account entirety scope examined thoroughly end-to-end basis ensured complete resolution attained desired objectives reached satisfactorily manner possible given constraints limitations existing conditions prevailing scenarios observed noted documented accordingly appropriately addressed suitably effectively efficiently timely fashion executed delivered successfully concluded finalized achieved accomplished ultimately resulting restored functionality reliability dependability expected anticipated required demanded necessitated obligated warranted justified mandated prescribed recommended endorsed advocated supported encouraged facilitated promoted advanced fostered nurtured cultivated sustained maintained preserved safeguarded protected secured guaranteed assured verified validated authenticated certified ratified approved authorized sanctioned permitted allowed recognized acknowledged accepted embraced appreciated valued esteemed cherished treasured regarded respected honored held upheld revered admired lauded praised acclaimed comm

Immediate Steps to Take When a Clog is Detected

Immediate Steps to Take When a Clog is Detected



When dealing with ventilation clogs, it's imperative to act swiftly to maintain air quality and ensure safety. Ventilation systems are crucial for circulating fresh air and removing pollutants, so a blockage can lead to discomfort or even health hazards. Here are some immediate steps to take when a clog is detected.

First, identify the signs of a clogged ventilation system. Common indicators include reduced airflow, unusual noises from the vents, unpleasant odors, or increased dust accumulation in your space. Once you've determined there's likely a clog, act quickly to minimize its impact.


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The initial step is to turn off the HVAC system. Continuing its operation could exacerbate existing blockages or damage components further down the line. By shutting it down immediately, you prevent additional pressure build-up and potential overheating of the system.

Next, inspect accessible areas of the ventilation system. Begin by checking vent covers and grilles; these often accumulate dust and debris over time. Remove them carefully and clean any visible obstructions using a vacuum cleaner or brush. Pay special attention to filters as well-clogged filters are common culprits in reducing airflow efficiency.

If cleaning vent covers doesn't resolve the issue, consider inspecting ductwork if it's safely accessible. Look for obvious blockages like nests or large debris that might have become lodged inside. For more complex systems where ducts aren't easily reachable without professional equipment, calling an expert may be necessary at this stage.

Once basic checks have been performed and any minor obstructions removed, replace all cleaned components securely before restarting your HVAC system. Monitor performance closely after reactivation; if normal airflow isn't restored promptly or problems persist-such as strange noises continuing-it's wise to contact professionals immediately.

In parallel with addressing physical clogs within your ventilation setup directly through removal efforts outlined above (where feasible), improving general housekeeping practices can mitigate future incidents significantly too: regular vacuuming around intakes/exhausts coupled alongside scheduled maintenance visits help uphold optimal functionality long-term while avoiding sudden emergent issues arising unexpectedly mid-operation later on otherwise unnecessarily instead potentially avoidably beforehand already proactively taken care-of thus far previously altogether accordingly likewise indeed overall fortunately enough thankfully!

To conclude succinctly yet comprehensively hereupon summatively still furthermore: detecting-and then resolving-a clog within one's respective ventilation network demands promptness decisiveness alike both together simultaneously combined effectively efficiently ultimately ideally optimally invariably consistently reliably dependably across-the-board without exception unfailingly always assuredly guaranteed inevitably conclusively intuitively logically sensibly pragmatically realistically practically soundly judiciously wisely smartly astutely shrewdly cleverly insightfully perceptively discerningly cautiously carefully attentively vigilantly watchfully conscientiously diligently thoroughly meticulously scrupulously methodically systematically strategically tactically adept proficient skilled capable competent qualified experienced knowledgeable informed aware conscious alert attentive observant responsive reactive adaptive flexible agile nimble quick swift fast rapid expeditious brisk prompt timely punctual precise accurate exact correct right proper fit suitable appropriate apt fitting relevant pertinent applicable useful beneficial advantageous favorable helpful constructive productive fruitful rewarding satisfactory pleasing satisfying gratifying fulfilling enjoyable delightful pleasant agreeable congenial amiable amicable friendly neighborly courteous polite civil respectful considerate thoughtful kind caring compassionate empathetic understanding sympathetic supportive encouraging motivating inspiring uplifting reassuring comforting soothing calming relaxing tranquil peaceful serene quiet gentle mild moderate temperate balanced harmonious stable steady constant consistent reliable dependable steadfast unwavering firm resolute determined decided committed dedicated devoted loyal faithful trustworthy honest sincere genuine authentic real true pure unadulterated uncontaminated unsullied pristine spotless flawless immaculate perfect impeccable faultless irreproachable blameless guiltless innocent virtuous righteous just fair equitable

Immediate Steps to Take When a Clog is Detected
Tools and Equipment for Clearing Blockages

Tools and Equipment for Clearing Blockages

Tools and Equipment for Clearing Blockages



When dealing with ventilation clogs, having the right tools and equipment is essential to ensure a swift and efficient resolution. Ventilation systems are crucial for maintaining indoor air quality, regulating temperature, and ensuring that spaces remain comfortable and safe for occupants. However, like any system, they can experience blockages which may lead to decreased efficiency or even pose health risks if not addressed promptly.

The first step in addressing a blocked ventilation system is to identify the location and cause of the blockage. This often requires basic inspection tools such as flashlights or portable cameras designed for ductwork. These cameras can navigate through vents, providing visual confirmation of blockages caused by debris, dust accumulation, or foreign objects inadvertently lodged within the ducts.

Once identified, various tools are available for clearing these obstructions. A common tool used is a flexible duct brush. These brushes come in different sizes to accommodate various duct diameters and feature long handles allowing them to reach deep into the ductwork. The bristles help dislodge accumulated dust and debris effectively without damaging the interior surfaces.

For more stubborn blockages, an air compressor might be employed. By directing high-pressure air into the ducts, it can blow out debris that has become tightly packed over time. This method is particularly useful when dealing with light materials such as dust bunnies or pet hair but should be used cautiously to avoid creating additional issues elsewhere in the system.

In cases where physical obstructions such as fallen insulation pieces or small animals are present within ducts, retrieval tools like grabbers or specialized vacuums may be necessary. Grabbers can extend into hard-to-reach areas to pull out larger items safely while minimizing damage risk to both the object being retrieved and the vent infrastructure itself.

Regular maintenance using these tools helps prevent severe blockages from occurring altogether. Scheduling periodic inspections and cleanings ensures that ventilation systems operate at peak efficiency year-round while also extending their overall lifespan.

Beyond mechanical solutions, chemical treatments might sometimes be considered depending on what kind of blockage you're facing-particularly if mold growth inside vents becomes apparent due to moisture accumulation combined with dirt build-up over time; however,such methods should always follow manufacturer guidelines carefully so as not harm surrounding components nor release harmful substances indoors unintentionally during application process itself either way though regular cleaning remains key preventative measure against needing harsher interventions later down line anyways!



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In conclusion,having proper set up ready beforehand makes handling unexpected clogs much easier task whenever they do arise thus preserving healthy environment home/workplace alike while safeguarding investments made towards keeping spaces well ventilated throughout year no matter season!

Preventive Measures to Avoid Future Clogs

Preventive Measures to Avoid Future Clogs



Ventilation systems are essential components in maintaining healthy indoor air quality and ensuring the efficient operation of heating, ventilation, and air conditioning (HVAC) units. However, like any other system, they can suffer from clogs that hinder their performance. While it is crucial to know what to do when ventilation clogs occur, it is equally important to implement preventive measures to avoid future clogs. By taking proactive steps, we can minimize disruptions, reduce maintenance costs, and extend the life of our ventilation systems.

One of the most effective preventive measures is regular maintenance and cleaning of the ventilation system. Dust, debris, and other particulates can accumulate over time within ducts and vents. Scheduling routine inspections with a qualified HVAC professional ensures that these contaminants are identified and removed before they cause significant blockages. Professionals use specialized tools to clean ductwork thoroughly, which not only helps maintain optimal airflow but also improves indoor air quality by reducing allergens and pollutants.

Another critical preventive measure is changing or cleaning air filters regularly. Air filters play a pivotal role in trapping dust and debris before they enter the ventilation system. Over time, filters can become clogged with particles they capture, significantly obstructing airflow if not replaced or cleaned frequently. Depending on the type of filter used-whether disposable or washable-it's advisable to check them every one to three months for residential settings or more frequently in commercial environments with higher pollutant levels.

In addition to regular maintenance practices, homeowners and facility managers should be mindful of their surroundings as factors like construction work or high pollen seasons can increase the amount of airborne debris entering a building's ventilation system. During such periods, covering vents temporarily or increasing the frequency of filter changes may be beneficial in preventing clogs.

Moreover, implementing proper sealing techniques during installation can prevent external elements from infiltrating into the ductwork through leaks or gaps. Properly sealed ducts ensure that all parts of the system are working efficiently without losing conditioned air due to leaks-an issue that not only leads to energy inefficiency but also encourages dirt accumulation within under-pressurized areas.

Finally, educating occupants about best practices regarding HVAC usage contributes significantly toward clog prevention efforts. Encouraging responsible behaviors such as keeping windows closed during high-pollen days minimizes unnecessary exposure while using exhaust fans correctly helps remove excess moisture-a common contributor towards mold growth within vents-which could exacerbate clogging issues if left unchecked.

In conclusion, preventing future clogs in ventilation systems requires diligence through regular maintenance routines combined with smart operational habits among users themselves-both aimed at minimizing potential blockages effectively over time rather than simply reacting after problems arise unexpectedly later down track thereby saving both money long-term along well-being those inhabiting spaces serviced by these crucial networks daily basis!

Preventive Measures to Avoid Future Clogs
When to Call a Professional HVAC Technician

When to Call a Professional HVAC Technician



When to Call a Professional HVAC Technician: What to Do When Ventilation Clogs Occur

Maintaining a comfortable and healthy environment within your home is largely dependent on the efficiency of your HVAC system. Central to this is proper ventilation, which ensures that air circulates effectively, maintaining indoor air quality and regulating temperature. However, there are times when ventilation clogs occur, disrupting the seamless flow of air and potentially leading to significant issues if not addressed promptly.

The first step in dealing with ventilation clogs is recognizing the signs that indicate a problem. These can include uneven heating or cooling throughout your home, increased energy bills due to your system working harder than necessary, unusual noises emanating from the vents, or an increase in dust accumulation despite regular cleaning. Additionally, you might notice that rooms feel stuffy or stale because fresh air isn't circulating as it should.

Once you've identified these symptoms, it's important to assess whether it's something you can manage yourself or if it's time to call in a professional HVAC technician. For minor blockages caused by dust buildup or debris near vent openings, homeowners might be able to address the issue with simple tools like vacuums or brushes. Regularly checking filters and replacing them every few months can also prevent minor clogs.

However, there are scenarios where calling a professional becomes essential. If you've attempted basic troubleshooting without improvement or if you're unable to locate the source of the blockage, it's wise to seek expert help. Professionals have specialized tools and knowledge that allow them to inspect ductwork thoroughly for obstructions deep within the system-something that's often beyond DIY capabilities.

Moreover, certain situations demand professional intervention immediately due to potential risks involved. For example, if you suspect mold growth within ducts due to persistent moisture issues or notice strange odors accompanying reduced airflow-these could pose health hazards that require thorough cleaning and sanitization only professionals can provide safely.

Another critical situation warranting expert attention involves any suspected damage within the ductwork itself; visible punctures or disconnections could lead not only to inefficient performance but also higher utility costs over time as conditioned air escapes through leaks rather than reaching intended spaces efficiently.



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Calling an HVAC technician is not just about fixing current problems; it's also about preventing future issues by ensuring everything operates optimally post-repair through routine maintenance advice tailored specifically for your setup at home (e.g., frequency recommendations regarding filter changes based on specific environmental factors).

In conclusion, while some ventilation clogging incidents may seem manageable independently initially-it's crucial never underestimate underlying complexities possibly present requiring trained expertise instead ultimately safeguarding both comfort levels indoors alongside long-term functionality preserved best via proactive measures undertaken collaboratively between informed homeowners supported aptly skilled technicians alike!

Rooftop HVAC unit with view of fresh-air intake vent
Ventilation duct with outlet diffuser vent. These are installed throughout a building to move air in or out of rooms. In the middle is a damper to open and close the vent to allow more or less air to enter the space.
The control circuit in a household HVAC installation. The wires connecting to the blue terminal block on the upper-right of the board lead to the thermostat. The fan enclosure is directly behind the board, and the filters can be seen at the top. The safety interlock switch is at the bottom left. In the lower middle is the capacitor.

Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation as HVAC&R or HVACR, or "ventilation" is dropped, as in HACR (as in the designation of HACR-rated circuit breakers).

HVAC is an important part of residential structures such as single family homes, apartment buildings, hotels, and senior living facilities; medium to large industrial and office buildings such as skyscrapers and hospitals; vehicles such as cars, trains, airplanes, ships and submarines; and in marine environments, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh air from outdoors.

Ventilating or ventilation (the "V" in HVAC) is the process of exchanging or replacing air in any space to provide high indoor air quality which involves temperature control, oxygen replenishment, and removal of moisture, odors, smoke, heat, dust, airborne bacteria, carbon dioxide, and other gases. Ventilation removes unpleasant smells and excessive moisture, introduces outside air, keeps interior building air circulating, and prevents stagnation of the interior air. Methods for ventilating a building are divided into mechanical/forced and natural types.[1]

Overview

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The three major functions of heating, ventilation, and air conditioning are interrelated, especially with the need to provide thermal comfort and acceptable indoor air quality within reasonable installation, operation, and maintenance costs. HVAC systems can be used in both domestic and commercial environments. HVAC systems can provide ventilation, and maintain pressure relationships between spaces. The means of air delivery and removal from spaces is known as room air distribution.[2]

Individual systems

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In modern buildings, the design, installation, and control systems of these functions are integrated into one or more HVAC systems. For very small buildings, contractors normally estimate the capacity and type of system needed and then design the system, selecting the appropriate refrigerant and various components needed. For larger buildings, building service designers, mechanical engineers, or building services engineers analyze, design, and specify the HVAC systems. Specialty mechanical contractors and suppliers then fabricate, install and commission the systems. Building permits and code-compliance inspections of the installations are normally required for all sizes of buildings

District networks

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Although HVAC is executed in individual buildings or other enclosed spaces (like NORAD's underground headquarters), the equipment involved is in some cases an extension of a larger district heating (DH) or district cooling (DC) network, or a combined DHC network. In such cases, the operating and maintenance aspects are simplified and metering becomes necessary to bill for the energy that is consumed, and in some cases energy that is returned to the larger system. For example, at a given time one building may be utilizing chilled water for air conditioning and the warm water it returns may be used in another building for heating, or for the overall heating-portion of the DHC network (likely with energy added to boost the temperature).[3][4][5]

Basing HVAC on a larger network helps provide an economy of scale that is often not possible for individual buildings, for utilizing renewable energy sources such as solar heat,[6][7][8] winter's cold,[9][10] the cooling potential in some places of lakes or seawater for free cooling, and the enabling function of seasonal thermal energy storage. By utilizing natural sources that can be used for HVAC systems it can make a huge difference for the environment and help expand the knowledge of using different methods.

History

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HVAC is based on inventions and discoveries made by Nikolay Lvov, Michael Faraday, Rolla C. Carpenter, Willis Carrier, Edwin Ruud, Reuben Trane, James Joule, William Rankine, Sadi Carnot, Alice Parker and many others.[11]

Multiple inventions within this time frame preceded the beginnings of the first comfort air conditioning system, which was designed in 1902 by Alfred Wolff (Cooper, 2003) for the New York Stock Exchange, while Willis Carrier equipped the Sacketts-Wilhems Printing Company with the process AC unit the same year. Coyne College was the first school to offer HVAC training in 1899.[12] The first residential AC was installed by 1914, and by the 1950s there was "widespread adoption of residential AC".[13]

The invention of the components of HVAC systems went hand-in-hand with the Industrial Revolution, and new methods of modernization, higher efficiency, and system control are constantly being introduced by companies and inventors worldwide.

Heating

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Heaters are appliances whose purpose is to generate heat (i.e. warmth) for the building. This can be done via central heating. Such a system contains a boiler, furnace, or heat pump to heat water, steam, or air in a central location such as a furnace room in a home, or a mechanical room in a large building. The heat can be transferred by convection, conduction, or radiation. Space heaters are used to heat single rooms and only consist of a single unit.

Generation

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Central heating unit

Heaters exist for various types of fuel, including solid fuels, liquids, and gases. Another type of heat source is electricity, normally heating ribbons composed of high resistance wire (see Nichrome). This principle is also used for baseboard heaters and portable heaters. Electrical heaters are often used as backup or supplemental heat for heat pump systems.

The heat pump gained popularity in the 1950s in Japan and the United States.[14] Heat pumps can extract heat from various sources, such as environmental air, exhaust air from a building, or from the ground. Heat pumps transfer heat from outside the structure into the air inside. Initially, heat pump HVAC systems were only used in moderate climates, but with improvements in low temperature operation and reduced loads due to more efficient homes, they are increasing in popularity in cooler climates. They can also operate in reverse to cool an interior.

Distribution

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Water/steam

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In the case of heated water or steam, piping is used to transport the heat to the rooms. Most modern hot water boiler heating systems have a circulator, which is a pump, to move hot water through the distribution system (as opposed to older gravity-fed systems). The heat can be transferred to the surrounding air using radiators, hot water coils (hydro-air), or other heat exchangers. The radiators may be mounted on walls or installed within the floor to produce floor heat.

The use of water as the heat transfer medium is known as hydronics. The heated water can also supply an auxiliary heat exchanger to supply hot water for bathing and washing.

Air

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Warm air systems distribute the heated air through ductwork systems of supply and return air through metal or fiberglass ducts. Many systems use the same ducts to distribute air cooled by an evaporator coil for air conditioning. The air supply is normally filtered through air filters[dubiousdiscuss] to remove dust and pollen particles.[15]

Dangers

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The use of furnaces, space heaters, and boilers as a method of indoor heating could result in incomplete combustion and the emission of carbon monoxide, nitrogen oxides, formaldehyde, volatile organic compounds, and other combustion byproducts. Incomplete combustion occurs when there is insufficient oxygen; the inputs are fuels containing various contaminants and the outputs are harmful byproducts, most dangerously carbon monoxide, which is a tasteless and odorless gas with serious adverse health effects.[16]

Without proper ventilation, carbon monoxide can be lethal at concentrations of 1000 ppm (0.1%). However, at several hundred ppm, carbon monoxide exposure induces headaches, fatigue, nausea, and vomiting. Carbon monoxide binds with hemoglobin in the blood, forming carboxyhemoglobin, reducing the blood's ability to transport oxygen. The primary health concerns associated with carbon monoxide exposure are its cardiovascular and neurobehavioral effects. Carbon monoxide can cause atherosclerosis (the hardening of arteries) and can also trigger heart attacks. Neurologically, carbon monoxide exposure reduces hand to eye coordination, vigilance, and continuous performance. It can also affect time discrimination.[17]

Ventilation

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Ventilation is the process of changing or replacing air in any space to control the temperature or remove any combination of moisture, odors, smoke, heat, dust, airborne bacteria, or carbon dioxide, and to replenish oxygen. It plays a critical role in maintaining a healthy indoor environment by preventing the buildup of harmful pollutants and ensuring the circulation of fresh air. Different methods, such as natural ventilation through windows and mechanical ventilation systems, can be used depending on the building design and air quality needs. Ventilation often refers to the intentional delivery of the outside air to the building indoor space. It is one of the most important factors for maintaining acceptable indoor air quality in buildings.

Although ventilation is an integral component of maintaining good indoor air quality, it may not be satisfactory alone.[18] A clear understanding of both indoor and outdoor air quality parameters is needed to improve the performance of ventilation in terms of ...[19] In scenarios where outdoor pollution would deteriorate indoor air quality, other treatment devices such as filtration may also be necessary.[20]

Methods for ventilating a building may be divided into mechanical/forced and natural types.[21]

Mechanical or forced

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HVAC ventilation exhaust for a 12-story building
An axial belt-drive exhaust fan serving an underground car park. This exhaust fan's operation is interlocked with the concentration of contaminants emitted by internal combustion engines.

Mechanical, or forced, ventilation is provided by an air handler (AHU) and used to control indoor air quality. Excess humidity, odors, and contaminants can often be controlled via dilution or replacement with outside air. However, in humid climates more energy is required to remove excess moisture from ventilation air.

Kitchens and bathrooms typically have mechanical exhausts to control odors and sometimes humidity. Factors in the design of such systems include the flow rate (which is a function of the fan speed and exhaust vent size) and noise level. Direct drive fans are available for many applications and can reduce maintenance needs.

In summer, ceiling fans and table/floor fans circulate air within a room for the purpose of reducing the perceived temperature by increasing evaporation of perspiration on the skin of the occupants. Because hot air rises, ceiling fans may be used to keep a room warmer in the winter by circulating the warm stratified air from the ceiling to the floor.

Passive

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Ventilation on the downdraught system, by impulsion, or the 'plenum' principle, applied to schoolrooms (1899)

Natural ventilation is the ventilation of a building with outside air without using fans or other mechanical systems. It can be via operable windows, louvers, or trickle vents when spaces are small and the architecture permits. ASHRAE defined Natural ventilation as the flow of air through open windows, doors, grilles, and other planned building envelope penetrations, and as being driven by natural and/or artificially produced pressure differentials.[1]

Natural ventilation strategies also include cross ventilation, which relies on wind pressure differences on opposite sides of a building. By strategically placing openings, such as windows or vents, on opposing walls, air is channeled through the space to enhance cooling and ventilation. Cross ventilation is most effective when there are clear, unobstructed paths for airflow within the building.

In more complex schemes, warm air is allowed to rise and flow out high building openings to the outside (stack effect), causing cool outside air to be drawn into low building openings. Natural ventilation schemes can use very little energy, but care must be taken to ensure comfort. In warm or humid climates, maintaining thermal comfort solely via natural ventilation might not be possible. Air conditioning systems are used, either as backups or supplements. Air-side economizers also use outside air to condition spaces, but do so using fans, ducts, dampers, and control systems to introduce and distribute cool outdoor air when appropriate.

An important component of natural ventilation is air change rate or air changes per hour: the hourly rate of ventilation divided by the volume of the space. For example, six air changes per hour means an amount of new air, equal to the volume of the space, is added every ten minutes. For human comfort, a minimum of four air changes per hour is typical, though warehouses might have only two. Too high of an air change rate may be uncomfortable, akin to a wind tunnel which has thousands of changes per hour. The highest air change rates are for crowded spaces, bars, night clubs, commercial kitchens at around 30 to 50 air changes per hour.[22]

Room pressure can be either positive or negative with respect to outside the room. Positive pressure occurs when there is more air being supplied than exhausted, and is common to reduce the infiltration of outside contaminants.[23]

Airborne diseases

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Natural ventilation [24] is a key factor in reducing the spread of airborne illnesses such as tuberculosis, the common cold, influenza, meningitis or COVID-19. Opening doors and windows are good ways to maximize natural ventilation, which would make the risk of airborne contagion much lower than with costly and maintenance-requiring mechanical systems. Old-fashioned clinical areas with high ceilings and large windows provide the greatest protection. Natural ventilation costs little and is maintenance free, and is particularly suited to limited-resource settings and tropical climates, where the burden of TB and institutional TB transmission is highest. In settings where respiratory isolation is difficult and climate permits, windows and doors should be opened to reduce the risk of airborne contagion. Natural ventilation requires little maintenance and is inexpensive.[25]

Natural ventilation is not practical in much of the infrastructure because of climate. This means that the facilities need to have effective mechanical ventilation systems and or use Ceiling Level UV or FAR UV ventilation systems.

Alpha Black Edition - Sirair Air conditioner with UVC (Ultraviolet Germicidal Irradiation)

Ventilation is measured in terms of Air Changes Per Hour (ACH). As of 2023, the CDC recommends that all spaces have a minimum of 5 ACH.[26] For hospital rooms with airborne contagions the CDC recommends a minimum of 12 ACH.[27] The challenges in facility ventilation are public unawareness,[28][29] ineffective government oversight, poor building codes that are based on comfort levels, poor system operations, poor maintenance, and lack of transparency.[30]

UVC or Ultraviolet Germicidal Irradiation is a function used in modern air conditioners which reduces airborne viruses, bacteria, and fungi, through the use of a built-in LED UV light that emits a gentle glow across the evaporator. As the cross-flow fan circulates the room air, any viruses are guided through the sterilization module’s irradiation range, rendering them instantly inactive.[31]

Air conditioning

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An air conditioning system, or a standalone air conditioner, provides cooling and/or humidity control for all or part of a building. Air conditioned buildings often have sealed windows, because open windows would work against the system intended to maintain constant indoor air conditions. Outside, fresh air is generally drawn into the system by a vent into a mix air chamber for mixing with the space return air. Then the mixture air enters an indoor or outdoor heat exchanger section where the air is to be cooled down, then be guided to the space creating positive air pressure. The percentage of return air made up of fresh air can usually be manipulated by adjusting the opening of this vent. Typical fresh air intake is about 10% of the total supply air.[citation needed]

Air conditioning and refrigeration are provided through the removal of heat. Heat can be removed through radiation, convection, or conduction. The heat transfer medium is a refrigeration system, such as water, air, ice, and chemicals are referred to as refrigerants. A refrigerant is employed either in a heat pump system in which a compressor is used to drive thermodynamic refrigeration cycle, or in a free cooling system that uses pumps to circulate a cool refrigerant (typically water or a glycol mix).

It is imperative that the air conditioning horsepower is sufficient for the area being cooled. Underpowered air conditioning systems will lead to power wastage and inefficient usage. Adequate horsepower is required for any air conditioner installed.

Refrigeration cycle

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A simple stylized diagram of the refrigeration cycle: 1) condensing coil, 2) expansion valve, 3) evaporating coil, 4) compressor

The refrigeration cycle uses four essential elements to cool, which are compressor, condenser, metering device, and evaporator.

  • At the inlet of a compressor, the refrigerant inside the system is in a low pressure, low temperature, gaseous state. The compressor pumps the refrigerant gas up to high pressure and temperature.
  • From there it enters a heat exchanger (sometimes called a condensing coil or condenser) where it loses heat to the outside, cools, and condenses into its liquid phase.
  • An expansion valve (also called metering device) regulates the refrigerant liquid to flow at the proper rate.
  • The liquid refrigerant is returned to another heat exchanger where it is allowed to evaporate, hence the heat exchanger is often called an evaporating coil or evaporator. As the liquid refrigerant evaporates it absorbs heat from the inside air, returns to the compressor, and repeats the cycle. In the process, heat is absorbed from indoors and transferred outdoors, resulting in cooling of the building.

In variable climates, the system may include a reversing valve that switches from heating in winter to cooling in summer. By reversing the flow of refrigerant, the heat pump refrigeration cycle is changed from cooling to heating or vice versa. This allows a facility to be heated and cooled by a single piece of equipment by the same means, and with the same hardware.

Free cooling

[edit]

Free cooling systems can have very high efficiencies, and are sometimes combined with seasonal thermal energy storage so that the cold of winter can be used for summer air conditioning. Common storage mediums are deep aquifers or a natural underground rock mass accessed via a cluster of small-diameter, heat-exchanger-equipped boreholes. Some systems with small storages are hybrids, using free cooling early in the cooling season, and later employing a heat pump to chill the circulation coming from the storage. The heat pump is added-in because the storage acts as a heat sink when the system is in cooling (as opposed to charging) mode, causing the temperature to gradually increase during the cooling season.

Some systems include an "economizer mode", which is sometimes called a "free-cooling mode". When economizing, the control system will open (fully or partially) the outside air damper and close (fully or partially) the return air damper. This will cause fresh, outside air to be supplied to the system. When the outside air is cooler than the demanded cool air, this will allow the demand to be met without using the mechanical supply of cooling (typically chilled water or a direct expansion "DX" unit), thus saving energy. The control system can compare the temperature of the outside air vs. return air, or it can compare the enthalpy of the air, as is frequently done in climates where humidity is more of an issue. In both cases, the outside air must be less energetic than the return air for the system to enter the economizer mode.

Packaged split system

[edit]

Central, "all-air" air-conditioning systems (or package systems) with a combined outdoor condenser/evaporator unit are often installed in North American residences, offices, and public buildings, but are difficult to retrofit (install in a building that was not designed to receive it) because of the bulky air ducts required.[32] (Minisplit ductless systems are used in these situations.) Outside of North America, packaged systems are only used in limited applications involving large indoor space such as stadiums, theatres or exhibition halls.

An alternative to packaged systems is the use of separate indoor and outdoor coils in split systems. Split systems are preferred and widely used worldwide except in North America. In North America, split systems are most often seen in residential applications, but they are gaining popularity in small commercial buildings. Split systems are used where ductwork is not feasible or where the space conditioning efficiency is of prime concern.[33] The benefits of ductless air conditioning systems include easy installation, no ductwork, greater zonal control, flexibility of control, and quiet operation.[34] In space conditioning, the duct losses can account for 30% of energy consumption.[35] The use of minisplits can result in energy savings in space conditioning as there are no losses associated with ducting.

With the split system, the evaporator coil is connected to a remote condenser unit using refrigerant piping between an indoor and outdoor unit instead of ducting air directly from the outdoor unit. Indoor units with directional vents mount onto walls, suspended from ceilings, or fit into the ceiling. Other indoor units mount inside the ceiling cavity so that short lengths of duct handle air from the indoor unit to vents or diffusers around the rooms.

Split systems are more efficient and the footprint is typically smaller than the package systems. On the other hand, package systems tend to have a slightly lower indoor noise level compared to split systems since the fan motor is located outside.

Dehumidification

[edit]

Dehumidification (air drying) in an air conditioning system is provided by the evaporator. Since the evaporator operates at a temperature below the dew point, moisture in the air condenses on the evaporator coil tubes. This moisture is collected at the bottom of the evaporator in a pan and removed by piping to a central drain or onto the ground outside.

A dehumidifier is an air-conditioner-like device that controls the humidity of a room or building. It is often employed in basements that have a higher relative humidity because of their lower temperature (and propensity for damp floors and walls). In food retailing establishments, large open chiller cabinets are highly effective at dehumidifying the internal air. Conversely, a humidifier increases the humidity of a building.

The HVAC components that dehumidify the ventilation air deserve careful attention because outdoor air constitutes most of the annual humidity load for nearly all buildings.[36]

Humidification

[edit]

Maintenance

[edit]

All modern air conditioning systems, even small window package units, are equipped with internal air filters.[citation needed] These are generally of a lightweight gauze-like material, and must be replaced or washed as conditions warrant. For example, a building in a high dust environment, or a home with furry pets, will need to have the filters changed more often than buildings without these dirt loads. Failure to replace these filters as needed will contribute to a lower heat exchange rate, resulting in wasted energy, shortened equipment life, and higher energy bills; low air flow can result in iced-over evaporator coils, which can completely stop airflow. Additionally, very dirty or plugged filters can cause overheating during a heating cycle, which can result in damage to the system or even fire.

Because an air conditioner moves heat between the indoor coil and the outdoor coil, both must be kept clean. This means that, in addition to replacing the air filter at the evaporator coil, it is also necessary to regularly clean the condenser coil. Failure to keep the condenser clean will eventually result in harm to the compressor because the condenser coil is responsible for discharging both the indoor heat (as picked up by the evaporator) and the heat generated by the electric motor driving the compressor.

Energy efficiency

[edit]

HVAC is significantly responsible for promoting energy efficiency of buildings as the building sector consumes the largest percentage of global energy.[37] Since the 1980s, manufacturers of HVAC equipment have been making an effort to make the systems they manufacture more efficient. This was originally driven by rising energy costs, and has more recently been driven by increased awareness of environmental issues. Additionally, improvements to the HVAC system efficiency can also help increase occupant health and productivity.[38] In the US, the EPA has imposed tighter restrictions over the years. There are several methods for making HVAC systems more efficient.

Heating energy

[edit]

In the past, water heating was more efficient for heating buildings and was the standard in the United States. Today, forced air systems can double for air conditioning and are more popular.

Some benefits of forced air systems, which are now widely used in churches, schools, and high-end residences, are

  • Better air conditioning effects
  • Energy savings of up to 15–20%
  • Even conditioning[citation needed]

A drawback is the installation cost, which can be slightly higher than traditional HVAC systems.

Energy efficiency can be improved even more in central heating systems by introducing zoned heating. This allows a more granular application of heat, similar to non-central heating systems. Zones are controlled by multiple thermostats. In water heating systems the thermostats control zone valves, and in forced air systems they control zone dampers inside the vents which selectively block the flow of air. In this case, the control system is very critical to maintaining a proper temperature.

Forecasting is another method of controlling building heating by calculating the demand for heating energy that should be supplied to the building in each time unit.

Ground source heat pump

[edit]

Ground source, or geothermal, heat pumps are similar to ordinary heat pumps, but instead of transferring heat to or from outside air, they rely on the stable, even temperature of the earth to provide heating and air conditioning. Many regions experience seasonal temperature extremes, which would require large-capacity heating and cooling equipment to heat or cool buildings. For example, a conventional heat pump system used to heat a building in Montana's −57 °C (−70 °F) low temperature or cool a building in the highest temperature ever recorded in the US—57 °C (134 °F) in Death Valley, California, in 1913 would require a large amount of energy due to the extreme difference between inside and outside air temperatures. A metre below the earth's surface, however, the ground remains at a relatively constant temperature. Utilizing this large source of relatively moderate temperature earth, a heating or cooling system's capacity can often be significantly reduced. Although ground temperatures vary according to latitude, at 1.8 metres (6 ft) underground, temperatures generally only range from 7 to 24 °C (45 to 75 °F).

Solar air conditioning

[edit]

Photovoltaic solar panels offer a new way to potentially decrease the operating cost of air conditioning. Traditional air conditioners run using alternating current, and hence, any direct-current solar power needs to be inverted to be compatible with these units. New variable-speed DC-motor units allow solar power to more easily run them since this conversion is unnecessary, and since the motors are tolerant of voltage fluctuations associated with variance in supplied solar power (e.g., due to cloud cover).

Ventilation energy recovery

[edit]

Energy recovery systems sometimes utilize heat recovery ventilation or energy recovery ventilation systems that employ heat exchangers or enthalpy wheels to recover sensible or latent heat from exhausted air. This is done by transfer of energy from the stale air inside the home to the incoming fresh air from outside.

Air conditioning energy

[edit]

The performance of vapor compression refrigeration cycles is limited by thermodynamics.[39] These air conditioning and heat pump devices move heat rather than convert it from one form to another, so thermal efficiencies do not appropriately describe the performance of these devices. The Coefficient of performance (COP) measures performance, but this dimensionless measure has not been adopted. Instead, the Energy Efficiency Ratio (EER) has traditionally been used to characterize the performance of many HVAC systems. EER is the Energy Efficiency Ratio based on a 35 °C (95 °F) outdoor temperature. To more accurately describe the performance of air conditioning equipment over a typical cooling season a modified version of the EER, the Seasonal Energy Efficiency Ratio (SEER), or in Europe the ESEER, is used. SEER ratings are based on seasonal temperature averages instead of a constant 35 °C (95 °F) outdoor temperature. The current industry minimum SEER rating is 14 SEER. Engineers have pointed out some areas where efficiency of the existing hardware could be improved. For example, the fan blades used to move the air are usually stamped from sheet metal, an economical method of manufacture, but as a result they are not aerodynamically efficient. A well-designed blade could reduce the electrical power required to move the air by a third.[40]

Demand-controlled kitchen ventilation

[edit]

Demand-controlled kitchen ventilation (DCKV) is a building controls approach to controlling the volume of kitchen exhaust and supply air in response to the actual cooking loads in a commercial kitchen. Traditional commercial kitchen ventilation systems operate at 100% fan speed independent of the volume of cooking activity and DCKV technology changes that to provide significant fan energy and conditioned air savings. By deploying smart sensing technology, both the exhaust and supply fans can be controlled to capitalize on the affinity laws for motor energy savings, reduce makeup air heating and cooling energy, increasing safety, and reducing ambient kitchen noise levels.[41]

Air filtration and cleaning

[edit]
Air handling unit, used for heating, cooling, and filtering the air

Air cleaning and filtration removes particles, contaminants, vapors and gases from the air. The filtered and cleaned air then is used in heating, ventilation, and air conditioning. Air cleaning and filtration should be taken in account when protecting our building environments.[42] If present, contaminants can come out from the HVAC systems if not removed or filtered properly.

Clean air delivery rate (CADR) is the amount of clean air an air cleaner provides to a room or space. When determining CADR, the amount of airflow in a space is taken into account. For example, an air cleaner with a flow rate of 30 cubic metres (1,000 cu ft) per minute and an efficiency of 50% has a CADR of 15 cubic metres (500 cu ft) per minute. Along with CADR, filtration performance is very important when it comes to the air in our indoor environment. This depends on the size of the particle or fiber, the filter packing density and depth, and the airflow rate.[42]

Circulation of harmful substances

[edit]

Poorly maintained air conditioners/ventilation systems can harbor mold, bacteria, and other contaminants, which are then circulated throughout indoor spaces, contributing to ...[43]

Industry and standards

[edit]

The HVAC industry is a worldwide enterprise, with roles including operation and maintenance, system design and construction, equipment manufacturing and sales, and in education and research. The HVAC industry was historically regulated by the manufacturers of HVAC equipment, but regulating and standards organizations such as HARDI (Heating, Air-conditioning and Refrigeration Distributors International), ASHRAE, SMACNA, ACCA (Air Conditioning Contractors of America), Uniform Mechanical Code, International Mechanical Code, and AMCA have been established to support the industry and encourage high standards and achievement. (UL as an omnibus agency is not specific to the HVAC industry.)

The starting point in carrying out an estimate both for cooling and heating depends on the exterior climate and interior specified conditions. However, before taking up the heat load calculation, it is necessary to find fresh air requirements for each area in detail, as pressurization is an important consideration.

International

[edit]

ISO 16813:2006 is one of the ISO building environment standards.[44] It establishes the general principles of building environment design. It takes into account the need to provide a healthy indoor environment for the occupants as well as the need to protect the environment for future generations and promote collaboration among the various parties involved in building environmental design for sustainability. ISO16813 is applicable to new construction and the retrofit of existing buildings.[45]

The building environmental design standard aims to:[45]

  • provide the constraints concerning sustainability issues from the initial stage of the design process, with building and plant life cycle to be considered together with owning and operating costs from the beginning of the design process;
  • assess the proposed design with rational criteria for indoor air quality, thermal comfort, acoustical comfort, visual comfort, energy efficiency, and HVAC system controls at every stage of the design process;
  • iterate decisions and evaluations of the design throughout the design process.

United States

[edit]

Licensing

[edit]

In the United States, federal licensure is generally handled by EPA certified (for installation and service of HVAC devices).

Many U.S. states have licensing for boiler operation. Some of these are listed as follows:

Finally, some U.S. cities may have additional labor laws that apply to HVAC professionals.

Societies

[edit]

Many HVAC engineers are members of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). ASHRAE regularly organizes two annual technical committees and publishes recognized standards for HVAC design, which are updated every four years.[56]

Another popular society is AHRI, which provides regular information on new refrigeration technology, and publishes relevant standards and codes.

Codes

[edit]

Codes such as the UMC and IMC do include much detail on installation requirements, however. Other useful reference materials include items from SMACNA, ACGIH, and technical trade journals.

American design standards are legislated in the Uniform Mechanical Code or International Mechanical Code. In certain states, counties, or cities, either of these codes may be adopted and amended via various legislative processes. These codes are updated and published by the International Association of Plumbing and Mechanical Officials (IAPMO) or the International Code Council (ICC) respectively, on a 3-year code development cycle. Typically, local building permit departments are charged with enforcement of these standards on private and certain public properties.

Technicians

[edit]
HVAC Technician
Occupation
Occupation type
Vocational
Activity sectors
Construction
Description
Education required
Apprenticeship
Related jobs
Carpenter, electrician, plumber, welder

An HVAC technician is a tradesman who specializes in heating, ventilation, air conditioning, and refrigeration. HVAC technicians in the US can receive training through formal training institutions, where most earn associate degrees. Training for HVAC technicians includes classroom lectures and hands-on tasks, and can be followed by an apprenticeship wherein the recent graduate works alongside a professional HVAC technician for a temporary period.[57] HVAC techs who have been trained can also be certified in areas such as air conditioning, heat pumps, gas heating, and commercial refrigeration.

United Kingdom

[edit]

The Chartered Institution of Building Services Engineers is a body that covers the essential Service (systems architecture) that allow buildings to operate. It includes the electrotechnical, heating, ventilating, air conditioning, refrigeration and plumbing industries. To train as a building services engineer, the academic requirements are GCSEs (A-C) / Standard Grades (1-3) in Maths and Science, which are important in measurements, planning and theory. Employers will often want a degree in a branch of engineering, such as building environment engineering, electrical engineering or mechanical engineering. To become a full member of CIBSE, and so also to be registered by the Engineering Council UK as a chartered engineer, engineers must also attain an Honours Degree and a master's degree in a relevant engineering subject.[citation needed] CIBSE publishes several guides to HVAC design relevant to the UK market, and also the Republic of Ireland, Australia, New Zealand and Hong Kong. These guides include various recommended design criteria and standards, some of which are cited within the UK building regulations, and therefore form a legislative requirement for major building services works. The main guides are:

  • Guide A: Environmental Design
  • Guide B: Heating, Ventilating, Air Conditioning and Refrigeration
  • Guide C: Reference Data
  • Guide D: Transportation systems in Buildings
  • Guide E: Fire Safety Engineering
  • Guide F: Energy Efficiency in Buildings
  • Guide G: Public Health Engineering
  • Guide H: Building Control Systems
  • Guide J: Weather, Solar and Illuminance Data
  • Guide K: Electricity in Buildings
  • Guide L: Sustainability
  • Guide M: Maintenance Engineering and Management

Within the construction sector, it is the job of the building services engineer to design and oversee the installation and maintenance of the essential services such as gas, electricity, water, heating and lighting, as well as many others. These all help to make buildings comfortable and healthy places to live and work in. Building Services is part of a sector that has over 51,000 businesses and employs represents 2–3% of the GDP.

Australia

[edit]

The Air Conditioning and Mechanical Contractors Association of Australia (AMCA), Australian Institute of Refrigeration, Air Conditioning and Heating (AIRAH), Australian Refrigeration Mechanical Association and CIBSE are responsible.

Asia

[edit]

Asian architectural temperature-control have different priorities than European methods. For example, Asian heating traditionally focuses on maintaining temperatures of objects such as the floor or furnishings such as Kotatsu tables and directly warming people, as opposed to the Western focus, in modern periods, on designing air systems.

Philippines

[edit]

The Philippine Society of Ventilating, Air Conditioning and Refrigerating Engineers (PSVARE) along with Philippine Society of Mechanical Engineers (PSME) govern on the codes and standards for HVAC / MVAC (MVAC means "mechanical ventilation and air conditioning") in the Philippines.

India

[edit]

The Indian Society of Heating, Refrigerating and Air Conditioning Engineers (ISHRAE) was established to promote the HVAC industry in India. ISHRAE is an associate of ASHRAE. ISHRAE was founded at New Delhi[58] in 1981 and a chapter was started in Bangalore in 1989. Between 1989 & 1993, ISHRAE chapters were formed in all major cities in India.[citation needed]

See also

[edit]

References

[edit]
  1. ^ a b Ventilation and Infiltration chapter, Fundamentals volume of the ASHRAE Handbook, ASHRAE, Inc., Atlanta, GA, 2005
  2. ^ Designer's Guide to Ceiling-Based Air Diffusion, Rock and Zhu, ASHRAE, Inc., New York, 2002
  3. ^ Rezaie, Behnaz; Rosen, Marc A. (2012). "District heating and cooling: Review of technology and potential enhancements". Applied Energy. 93: 2–10. Bibcode:2012ApEn...93....2R. doi:10.1016/j.apenergy.2011.04.020.
  4. ^ Werner S. (2006). ECOHEATCOOL (WP4) Possibilities with more district heating in Europe. Euroheat & Power, Brussels. Archived 2015-09-24 at the Wayback Machine
  5. ^ Dalin P., Rubenhag A. (2006). ECOHEATCOOL (WP5) Possibilities with more district cooling in Europe, final report from the project. Final Rep. Brussels: Euroheat & Power. Archived 2012-10-15 at the Wayback Machine
  6. ^ Nielsen, Jan Erik (2014). Solar District Heating Experiences from Denmark. Energy Systems in the Alps - storage and distribution … Energy Platform Workshop 3, Zurich - 13/2 2014
  7. ^ Wong B., Thornton J. (2013). Integrating Solar & Heat Pumps. Renewable Heat Workshop.
  8. ^ Pauschinger T. (2012). Solar District Heating with Seasonal Thermal Energy Storage in Germany Archived 2016-10-18 at the Wayback Machine. European Sustainable Energy Week, Brussels. 18–22 June 2012.
  9. ^ "How Renewable Energy Is Redefining HVAC | AltEnergyMag". www.altenergymag.com. Retrieved 2020-09-29.
  10. ^ ""Lake Source" Heat Pump System". HVAC-Talk: Heating, Air & Refrigeration Discussion. Retrieved 2020-09-29.
  11. ^ Swenson, S. Don (1995). HVAC: heating, ventilating, and air conditioning. Homewood, Illinois: American Technical Publishers. ISBN 978-0-8269-0675-5.
  12. ^ "History of Heating, Air Conditioning & Refrigeration". Coyne College. Archived from the original on August 28, 2016.
  13. ^ "What is HVAC? A Comprehensive Guide".
  14. ^ Staffell, Iain; Brett, Dan; Brandon, Nigel; Hawkes, Adam (30 May 2014). "A review of domestic heat pumps".
  15. ^ (Alta.), Edmonton. Edmonton's green home guide : you're gonna love green. OCLC 884861834.
  16. ^ Bearg, David W. (1993). Indoor Air Quality and HVAC Systems. New York: Lewis Publishers. pp. 107–112.
  17. ^ Dianat, I.; Nazari, I. "Characteristic of unintentional carbon monoxide poisoning in Northwest Iran-Tabriz". International Journal of Injury Control and Promotion. Retrieved 2011-11-15.
  18. ^ ANSI/ASHRAE Standard 62.1, Ventilation for Acceptable Indoor Air Quality, ASHRAE, Inc., Atlanta, GA, US
  19. ^ Belias, Evangelos; Licina, Dusan (2024). "European residential ventilation: Investigating the impact on health and energy demand". Energy and Buildings. 304. Bibcode:2024EneBu.30413839B. doi:10.1016/j.enbuild.2023.113839.
  20. ^ Belias, Evangelos; Licina, Dusan (2022). "Outdoor PM2. 5 air filtration: optimising indoor air quality and energy". Building & Cities. 3 (1): 186–203. doi:10.5334/bc.153.
  21. ^ Ventilation and Infiltration chapter, Fundamentals volume of the ASHRAE Handbook, ASHRAE, Inc., Atlanta, Georgia, 2005
  22. ^ "Air Change Rates for typical Rooms and Buildings". The Engineering ToolBox. Retrieved 2012-12-12.
  23. ^ Bell, Geoffrey. "Room Air Change Rate". A Design Guide for Energy-Efficient Research Laboratories. Archived from the original on 2011-11-17. Retrieved 2011-11-15.
  24. ^ "Natural Ventilation for Infection Control in Health-Care Settings" (PDF). World Health Organization (WHO), 2009. Retrieved 2021-07-05.
  25. ^ Escombe, A. R.; Oeser, C. C.; Gilman, R. H.; et al. (2007). "Natural ventilation for the prevention of airborne contagion". PLOS Med. 4 (68): e68. doi:10.1371/journal.pmed.0040068. PMC 1808096. PMID 17326709.
  26. ^ Centers For Disease Control and Prevention (CDC) "Improving Ventilation In Buildings". 11 February 2020.
  27. ^ Centers For Disease Control and Prevention (CDC) "Guidelines for Environmental Infection Control in Health-Care Facilities". 22 July 2019.
  28. ^ Dr. Edward A. Nardell Professor of Global Health and Social Medicine, Harvard Medical School "If We're Going to Live With COVID-19, It's Time to Clean Our Indoor Air Properly". Time. February 2022.
  29. ^ "A Paradigm Shift to Combat Indoor Respiratory Infection - 21st century" (PDF). University of Leeds., Morawska, L, Allen, J, Bahnfleth, W et al. (36 more authors) (2021) A paradigm shift to combat indoor respiratory infection. Science, 372 (6543). pp. 689-691. ISSN 0036-8075
  30. ^ Video "Building Ventilation What Everyone Should Know". YouTube. 17 June 2022.
  31. ^ CDC (June 1, 2020). "Center for Disease Control and Prevention, Decontamination and Reuse of Filtering Facepiece Respirators". cdc.gov. Retrieved September 13, 2024.
  32. ^ "What are Air Ducts? The Homeowner's Guide to HVAC Ductwork". Super Tech. Retrieved 2018-05-14.
  33. ^ "Ductless Mini-Split Heat Pumps". U.S. Department of Energy.
  34. ^ "The Pros and Cons of Ductless Mini Split Air Conditioners". Home Reference. 28 July 2018. Retrieved 9 September 2020.
  35. ^ "Ductless Mini-Split Air Conditioners". ENERGY SAVER. Retrieved 29 November 2019.
  36. ^ Moisture Control Guidance for Building Design, Construction and Maintenance. December 2013.
  37. ^ Chenari, B., Dias Carrilho, J. and Gameiro da Silva, M., 2016. Towards sustainable, energy-efficient and healthy ventilation strategies in buildings: A review. Renewable and Sustainable Energy Reviews, 59, pp.1426-1447.
  38. ^ "Sustainable Facilities Tool: HVAC System Overview". sftool.gov. Retrieved 2 July 2014.
  39. ^ "Heating and Air Conditioning". www.nuclear-power.net. Retrieved 2018-02-10.
  40. ^ Keeping cool and green, The Economist 17 July 2010, p. 83
  41. ^ "Technology Profile: Demand Control Kitchen Ventilation (DCKV)" (PDF). Retrieved 2018-12-04.
  42. ^ a b Howard, J (2003), Guidance for Filtration and Air-Cleaning Systems to Protect Building Environments from Airborne Chemical, Biological, or Radiological Attacks, National Institute for Occupational Safety and Health, doi:10.26616/NIOSHPUB2003136, 2003-136
  43. ^ "The Inside Story: A Guide to Indoor Air Quality". 28 August 2014.
  44. ^ ISO. "Building environment standards". www.iso.org. Retrieved 2011-05-14.
  45. ^ a b ISO. "Building environment design—Indoor environment—General principles". Retrieved 14 May 2011.
  46. ^ "010.01.02 Ark. Code R. § 002 - Chapter 13 - Restricted Lifetime License".
  47. ^ "Boiler Professionals Training and Licensing".
  48. ^ "Michigan Boiler Rules".
  49. ^ "Minn. R. 5225.0550 - EXPERIENCE REQUIREMENTS AND DOCUMENTATION FOR LICENSURE AS AN OPERATING ENGINEER".
  50. ^ "Subchapter 24.122.5 - Licensing".
  51. ^ "Chapter 90 - BOILERS, PRESSURE VESSELS, AND REFRIGERATION".
  52. ^ "Article 33.1-14 - North Dakota Boiler Rules".
  53. ^ "Ohio Admin. Code 1301:3-5-10 - Boiler operator and steam engineer experience requirements".
  54. ^ "Subchapter 13 - Licensing of Boiler and Pressure Vessel Service, Repair and/or Installers".
  55. ^ "Or. Admin. R. 918-225-0691 - Boiler, Pressure Vessel and Pressure Piping Installation, Alteration or Repair Licensing Requirements".
  56. ^ "ASHRAE Handbook Online". www.ashrae.org. Retrieved 2020-06-17.
  57. ^ "Heating, Air Conditioning, and Refrigeration Mechanics and Installers : Occupational Outlook Handbook: : U.S. Bureau of Labor Statistics". www.bls.gov. Retrieved 2023-06-22.
  58. ^ "About ISHRAE". ISHRAE. Retrieved 2021-10-11.

Further reading

[edit]
[edit]

Media related to Climate control at Wikimedia Commons

Related media at Wikimedia Commons:

 

 

External heat exchanger of an air-source heat pump for both heating and cooling
Mitsubishi heat pump interior air handler wall unit

A heat pump is a device that uses electricity to transfer heat from a colder place to a warmer place. Specifically, the heat pump transfers thermal energy using a heat pump and refrigeration cycle, cooling the cool space and warming the warm space.[1] In winter a heat pump can move heat from the cool outdoors to warm a house; the pump may also be designed to move heat from the house to the warmer outdoors in summer. As they transfer heat rather than generating heat, they are more energy-efficient than heating by gas boiler.[2]

A gaseous refrigerant is compressed so its pressure and temperature rise. When operating as a heater in cold weather, the warmed gas flows to a heat exchanger in the indoor space where some of its thermal energy is transferred to that indoor space, causing the gas to condense into a liquid. The liquified refrigerant flows to a heat exchanger in the outdoor space where the pressure falls, the liquid evaporates and the temperature of the gas falls. It is now colder than the temperature of the outdoor space being used as a heat source. It can again take up energy from the heat source, be compressed and repeat the cycle.

Air source heat pumps are the most common models, while other types include ground source heat pumps, water source heat pumps and exhaust air heat pumps.[3] Large-scale heat pumps are also used in district heating systems.[4]

The efficiency of a heat pump is expressed as a coefficient of performance (COP), or seasonal coefficient of performance (SCOP). The higher the number, the more efficient a heat pump is. For example, an air-to-water heat pump that produces 6kW at a SCOP of 4.62 will give over 4kW of energy into a heating system for every kilowatt of energy that the heat pump uses itself to operate. When used for space heating, heat pumps are typically more energy-efficient than electric resistance and other heaters.

Because of their high efficiency and the increasing share of fossil-free sources in electrical grids, heat pumps are playing a role in climate change mitigation.[5][6] Consuming 1 kWh of electricity, they can transfer 1[7] to 4.5 kWh of thermal energy into a building. The carbon footprint of heat pumps depends on how electricity is generated, but they usually reduce emissions.[8] Heat pumps could satisfy over 80% of global space and water heating needs with a lower carbon footprint than gas-fired condensing boilers: however, in 2021 they only met 10%.[4]

Principle of operation

[edit]
A: indoor compartment, B: outdoor compartment, I: insulation, 1: condenser, 2: expansion valve, 3: evaporator, 4: compressor

Heat flows spontaneously from a region of higher temperature to a region of lower temperature. Heat does not flow spontaneously from lower temperature to higher, but it can be made to flow in this direction if work is performed. The work required to transfer a given amount of heat is usually much less than the amount of heat; this is the motivation for using heat pumps in applications such as the heating of water and the interior of buildings.[9]

The amount of work required to drive an amount of heat Q from a lower-temperature reservoir such as ambient air to a higher-temperature reservoir such as the interior of a building is: where

  • is the work performed on the working fluid by the heat pump's compressor.
  • is the heat transferred from the lower-temperature reservoir to the higher-temperature reservoir.
  • is the instantaneous coefficient of performance for the heat pump at the temperatures prevailing in the reservoirs at one instant.

The coefficient of performance of a heat pump is greater than one so the work required is less than the heat transferred, making a heat pump a more efficient form of heating than electrical resistance heating. As the temperature of the higher-temperature reservoir increases in response to the heat flowing into it, the coefficient of performance decreases, causing an increasing amount of work to be required for each unit of heat being transferred.[9]

The coefficient of performance, and the work required by a heat pump can be calculated easily by considering an ideal heat pump operating on the reversed Carnot cycle:

  • If the low-temperature reservoir is at a temperature of 270 K (−3 °C) and the interior of the building is at 280 K (7 °C) the relevant coefficient of performance is 27. This means only 1 joule of work is required to transfer 27 joules of heat from a reservoir at 270 K to another at 280 K. The one joule of work ultimately ends up as thermal energy in the interior of the building so for each 27 joules of heat that are removed from the low-temperature reservoir, 28 joules of heat are added to the building interior, making the heat pump even more attractive from an efficiency perspective.[note 1]
  • As the temperature of the interior of the building rises progressively to 300 K (27 °C) the coefficient of performance falls progressively to 9. This means each joule of work is responsible for transferring 9 joules of heat out of the low-temperature reservoir and into the building. Again, the 1 joule of work ultimately ends up as thermal energy in the interior of the building so 10 joules of heat are added to the building interior.[note 2]

This is the theoretical amount of heat pumped but in practice it will be less for various reasons, for example if the outside unit has been installed where there is not enough airflow. More data sharing with owners and academics—perhaps from heat meters—could improve efficiency in the long run.[11]

History

[edit]

Milestones:

1748
William Cullen demonstrates artificial refrigeration.[12]
1834
Jacob Perkins patents a design for a practical refrigerator using dimethyl ether.[13]
1852
Lord Kelvin describes the theory underlying heat pumps.[14]
1855–1857
Peter von Rittinger develops and builds the first heat pump.[15]
1877
In the period before 1875, heat pumps were for the time being pursued for vapour compression evaporation (open heat pump process) in salt works with their obvious advantages for saving wood and coal. In 1857, Peter von Rittinger was the first to try to implement the idea of vapor compression in a small pilot plant. Presumably inspired by Rittinger's experiments in Ebensee, Antoine-Paul Piccard from the University of Lausanne and the engineer J. H. Weibel from the Weibel–Briquet company in Geneva built the world's first really functioning vapor compression system with a two-stage piston compressor. In 1877 this first heat pump in Switzerland was installed in the Bex salt works.[14][16]
1928
Aurel Stodola constructs a closed-loop heat pump (water source from Lake Geneva) which provides heating for the Geneva city hall to this day.[17][unreliable source?]
1937–1945
During the First World War, fuel prices were very high in Switzerland but it had plenty of hydropower.[14]: 18  In the period before and especially during the Second World War, when neutral Switzerland was completely surrounded by fascist-ruled countries, the coal shortage became alarming again. Thanks to their leading position in energy technology, the Swiss companies Sulzer, Escher Wyss and Brown Boveri built and put in operation around 35 heat pumps between 1937 and 1945. The main heat sources were lake water, river water, groundwater, and waste heat. Particularly noteworthy are the six historic heat pumps from the city of Zurich with heat outputs from 100 kW to 6 MW. An international milestone is the heat pump built by Escher Wyss in 1937/38 to replace the wood stoves in the City Hall of Zurich. To avoid noise and vibrations, a recently developed rotary piston compressor was used. This historic heat pump heated the town hall for 63 years until 2001. Only then was it replaced by a new, more efficient heat pump.[14]
1945
John Sumner, City Electrical Engineer for Norwich, installs an experimental water-source heat pump fed central heating system, using a nearby river to heat new Council administrative buildings. It had a seasonal efficiency ratio of 3.42, average thermal delivery of 147 kW, and peak output of 234 kW.[18]
1948
Robert C. Webber is credited as developing and building the first ground-source heat pump.[19]
1951
First large scale installation—the Royal Festival Hall in London is opened with a town gas-powered reversible water-source heat pump, fed by the Thames, for both winter heating and summer cooling needs.[18]
2019
The Kigali Amendment to phase out harmful refrigerants takes effect.

Types

[edit]

Air-source

[edit]
Heat pump on balcony of apartment

An air source heat pump (ASHP) is a heat pump that can absorb heat from air outside a building and release it inside; it uses the same vapor-compression refrigeration process and much the same equipment as an air conditioner, but in the opposite direction. ASHPs are the most common type of heat pump and, usually being smaller, tend to be used to heat individual houses or flats rather than blocks, districts or industrial processes.[20]

Air-to-air heat pumps provide hot or cold air directly to rooms, but do not usually provide hot water. Air-to-water heat pumps use radiators or underfloor heating to heat a whole house and are often also used to provide domestic hot water.

An ASHP can typically gain 4 kWh thermal energy from 1 kWh electric energy. They are optimized for flow temperatures between 30 and 40 °C (86 and 104 °F), suitable for buildings with heat emitters sized for low flow temperatures. With losses in efficiency, an ASHP can even provide full central heating with a flow temperature up to 80 °C (176 °F).[21]

As of 2023 about 10% of building heating worldwide is from ASHPs. They are the main way to phase out gas boilers (also known as "furnaces") from houses, to avoid their greenhouse gas emissions.[22]

Air-source heat pumps are used to move heat between two heat exchangers, one outside the building which is fitted with fins through which air is forced using a fan and the other which either directly heats the air inside the building or heats water which is then circulated around the building through radiators or underfloor heating which releases the heat to the building. These devices can also operate in a cooling mode where they extract heat via the internal heat exchanger and eject it into the ambient air using the external heat exchanger. Some can be used to heat water for washing which is stored in a domestic hot water tank.[23]

Air-source heat pumps are relatively easy and inexpensive to install, so are the most widely used type. In mild weather, coefficient of performance (COP) may be between 2 and 5, while at temperatures below around −8 °C (18 °F) an air-source heat pump may still achieve a COP of 1 to 4.[24]

While older air-source heat pumps performed relatively poorly at low temperatures and were better suited for warm climates, newer models with variable-speed compressors remain highly efficient in freezing conditions allowing for wide adoption and cost savings in places like Minnesota and Maine in the United States.[25]

Ground source

[edit]
 
A heat pump in combination with heat and cold storage

A ground source heat pump (also geothermal heat pump) is a heating/cooling system for buildings that use a type of heat pump to transfer heat to or from the ground, taking advantage of the relative constancy of temperatures of the earth through the seasons. Ground-source heat pumps (GSHPs)—or geothermal heat pumps (GHP), as they are commonly termed in North America—are among the most energy-efficient technologies for providing HVAC and water heating, using less energy than can be achieved by use of resistive electric heaters.

Efficiency is given as a coefficient of performance (CoP) which is typically in the range 3-6, meaning that the devices provide 3-6 units of heat for each unit of electricity used. Setup costs are higher than for other heating systems, due to the requirement of installing ground loops over large areas or of drilling bore holes, hence ground source is often installed when new blocks of flats are built.[26] Air-source heat pumps have lower set-up costs.

Heat recovery ventilation

[edit]

Exhaust air heat pumps extract heat from the exhaust air of a building and require mechanical ventilation. Two classes exist:

  • Exhaust air-air heat pumps transfer heat to intake air.
  • Exhaust air-water heat pumps transfer heat to a heating circuit that includes a tank of domestic hot water.

Solar-assisted

[edit]
 
Hybrid photovoltaic-thermal solar panels of a SAHP in an experimental installation at Department of Energy at Polytechnic of Milan

A solar-assisted heat pump (SAHP) is a machine that combines a heat pump and thermal solar panels and/or PV solar panels in a single integrated system.[27] Typically these two technologies are used separately (or only placing them in parallel) to produce hot water.[28] In this system the solar thermal panel performs the function of the low temperature heat source and the heat produced is used to feed the heat pump's evaporator.[29] The goal of this system is to get high coefficient of performance (COP) and then produce energy in a more efficient and less expensive way.

It is possible to use any type of solar thermal panel (sheet and tubes, roll-bond, heat pipe, thermal plates) or hybrid (mono/polycrystalline, thin film) in combination with the heat pump. The use of a hybrid panel is preferable because it allows covering a part of the electricity demand of the heat pump and reduce the power consumption and consequently the variable costs of the system.

Water-source

[edit]
Water-source heat exchanger being installed

A water-source heat pump works in a similar manner to a ground-source heat pump, except that it takes heat from a body of water rather than the ground. The body of water does, however, need to be large enough to be able to withstand the cooling effect of the unit without freezing or creating an adverse effect for wildlife.[30] The largest water-source heat pump was installed in the Danish town of Esbjerg in 2023.[31][32]

Others

[edit]

A thermoacoustic heat pump operates as a thermoacoustic heat engine without refrigerant but instead uses a standing wave in a sealed chamber driven by a loudspeaker to achieve a temperature difference across the chamber.[33]

Electrocaloric heat pumps are solid state.[34]

Applications

[edit]

The International Energy Agency estimated that, as of 2021, heat pumps installed in buildings have a combined capacity of more than 1000 GW.[4] They are used for heating, ventilation, and air conditioning (HVAC) and may also provide domestic hot water and tumble clothes drying.[35] The purchase costs are supported in various countries by consumer rebates.[36]

Space heating and sometimes also cooling

[edit]

In HVAC applications, a heat pump is typically a vapor-compression refrigeration device that includes a reversing valve and optimized heat exchangers so that the direction of heat flow (thermal energy movement) may be reversed. The reversing valve switches the direction of refrigerant through the cycle and therefore the heat pump may deliver either heating or cooling to a building.

Because the two heat exchangers, the condenser and evaporator, must swap functions, they are optimized to perform adequately in both modes. Therefore, the Seasonal Energy Efficiency Rating (SEER in the US) or European seasonal energy efficiency ratio of a reversible heat pump is typically slightly less than those of two separately optimized machines. For equipment to receive the US Energy Star rating, it must have a rating of at least 14 SEER. Pumps with ratings of 18 SEER or above are considered highly efficient. The highest efficiency heat pumps manufactured are up to 24 SEER.[37]

Heating seasonal performance factor (in the US) or Seasonal Performance Factor (in Europe) are ratings of heating performance. The SPF is Total heat output per annum / Total electricity consumed per annum in other words the average heating COP over the year.[38]

Window mounted heat pump

[edit]
Saddle-style window mounted heat pump 3D sketch

Window mounted heat pumps run on standard 120v AC outlets and provide heating, cooling, and humidity control. They are more efficient with lower noise levels, condensation management, and a smaller footprint than window mounted air conditioners that just do cooling.[39]

Water heating

[edit]

In water heating applications, heat pumps may be used to heat or preheat water for swimming pools, homes or industry. Usually heat is extracted from outdoor air and transferred to an indoor water tank.[40][41]

District heating

[edit]

Large (megawatt-scale) heat pumps are used for district heating.[42] However as of 2022 about 90% of district heat is from fossil fuels.[43] In Europe, heat pumps account for a mere 1% of heat supply in district heating networks but several countries have targets to decarbonise their networks between 2030 and 2040.[4] Possible sources of heat for such applications are sewage water, ambient water (e.g. sea, lake and river water), industrial waste heat, geothermal energy, flue gas, waste heat from district cooling and heat from solar seasonal thermal energy storage.[44] Large-scale heat pumps for district heating combined with thermal energy storage offer high flexibility for the integration of variable renewable energy. Therefore, they are regarded as a key technology for limiting climate change by phasing out fossil fuels.[44][45] They are also a crucial element of systems which can both heat and cool districts.[46]

Industrial heating

[edit]

There is great potential to reduce the energy consumption and related greenhouse gas emissions in industry by application of industrial heat pumps, for example for process heat.[47][48] Short payback periods of less than 2 years are possible, while achieving a high reduction of CO2 emissions (in some cases more than 50%).[49][50] Industrial heat pumps can heat up to 200 °C, and can meet the heating demands of many light industries.[51][52] In Europe alone, 15 GW of heat pumps could be installed in 3,000 facilities in the paper, food and chemicals industries.[4]

Performance

[edit]

The performance of a heat pump is determined by the ability of the pump to extract heat from a low temperature environment (the source) and deliver it to a higher temperature environment (the sink).[53] Performance varies, depending on installation details, temperature differences, site elevation, location on site, pipe runs, flow rates, and maintenance.

In general, heat pumps work most efficiently (that is, the heat output produced for a given energy input) when the difference between the heat source and the heat sink is small. When using a heat pump for space or water heating, therefore, the heat pump will be most efficient in mild conditions, and decline in efficiency on very cold days. Performance metrics supplied to consumers attempt to take this variation into account.

Common performance metrics are the SEER (in cooling mode) and seasonal coefficient of performance (SCOP) (commonly used just for heating), although SCOP can be used for both modes of operation.[53] Larger values of either metric indicate better performance.[53] When comparing the performance of heat pumps, the term performance is preferred to efficiency, with coefficient of performance (COP) being used to describe the ratio of useful heat movement per work input.[53] An electrical resistance heater has a COP of 1.0, which is considerably lower than a well-designed heat pump which will typically have a COP of 3 to 5 with an external temperature of 10 °C and an internal temperature of 20 °C. Because the ground is a constant temperature source, a ground-source heat pump is not subjected to large temperature fluctuations, and therefore is the most energy-efficient type of heat pump.[53]

The "seasonal coefficient of performance" (SCOP) is a measure of the aggregate energy efficiency measure over a period of one year which is dependent on regional climate.[53] One framework for this calculation is given by the Commission Regulation (EU) No. 813/2013.[54]

A heat pump's operating performance in cooling mode is characterized in the US by either its energy efficiency ratio (EER) or seasonal energy efficiency ratio (SEER), both of which have units of BTU/(h·W) (note that 1 BTU/(h·W) = 0.293 W/W) and larger values indicate better performance.

COP variation with output temperature
Pump type and source Typical use 35 °C
(e.g. heated screed floor)
45 °C
(e.g. heated screed floor)
55 °C
(e.g. heated timber floor)
65 °C
(e.g. radiator or DHW)
75 °C
(e.g. radiator and DHW)
85 °C
(e.g. radiator and DHW)
High-efficiency air-source heat pump (ASHP), air at −20 °C[55]   2.2 2.0 ‐ ‐ ‐ ‐
Two-stage ASHP, air at −20 °C[56] Low source temperature 2.4 2.2 1.9 ‐ ‐ ‐
High-efficiency ASHP, air at 0 °C[55] Low output temperature 3.8 2.8 2.2 2.0 ‐ ‐
Prototype transcritical CO
2
(R744) heat pump with tripartite gas cooler, source at 0 °C[57]
High output temperature 3.3 ‐ ‐ 4.2 ‐ 3.0
Ground-source heat pump (GSHP), water at 0 °C[55]   5.0 3.7 2.9 2.4 ‐ ‐
GSHP, ground at 10 °C[55] Low output temperature 7.2 5.0 3.7 2.9 2.4 ‐
Theoretical Carnot cycle limit, source −20 °C   5.6 4.9 4.4 4.0 3.7 3.4
Theoretical Carnot cycle limit, source 0 °C   8.8 7.1 6.0 5.2 4.6 4.2
Theoretical Lorentzen cycle limit (CO
2
pump), return fluid 25 °C, source 0 °C[57]
  10.1 8.8 7.9 7.1 6.5 6.1
Theoretical Carnot cycle limit, source 10 °C   12.3 9.1 7.3 6.1 5.4 4.8

Carbon footprint

[edit]

The carbon footprint of heat pumps depends on their individual efficiency and how electricity is produced. An increasing share of low-carbon energy sources such as wind and solar will lower the impact on the climate.

heating system emissions of energy source efficiency resulting emissions for thermal energy
heat pump with onshore wind power 11 gCO2/kWh[58] 400% (COP=4) 3 gCO2/kWh
heat pump with global electricity mix 436 gCO2/kWh[59] (2022) 400% (COP=4) 109 gCO2/kWh
natural-gas thermal (high efficiency) 201 gCO2/kWh[60] 90%[citation needed] 223 gCO2/kWh
heat pump
electricity by lignite (old power plant)
and low performance
1221 gCO2/kWh[60] 300% (COP=3) 407 gCO2/kWh

In most settings, heat pumps will reduce CO2 emissions compared to heating systems powered by fossil fuels.[61] In regions accounting for 70% of world energy consumption, the emissions savings of heat pumps compared with a high-efficiency gas boiler are on average above 45% and reach 80% in countries with cleaner electricity mixes.[4] These values can be improved by 10 percentage points, respectively, with alternative refrigerants. In the United States, 70% of houses could reduce emissions by installing a heat pump.[62][4] The rising share of renewable electricity generation in many countries is set to increase the emissions savings from heat pumps over time.[4]

Heating systems powered by green hydrogen are also low-carbon and may become competitors, but are much less efficient due to the energy loss associated with hydrogen conversion, transport and use. In addition, not enough green hydrogen is expected to be available before the 2030s or 2040s.[63][64]

Operation

[edit]
Figure 2: Temperature–entropy diagram of the vapor-compression cycle
An internal view of the outdoor unit of an Ecodan air source heat pump
Large heat pump setup for a commercial building
Wiring and connections to a central air unit inside

Vapor-compression uses a circulating refrigerant as the medium which absorbs heat from one space, compresses it thereby increasing its temperature before releasing it in another space. The system normally has eight main components: a compressor, a reservoir, a reversing valve which selects between heating and cooling mode, two thermal expansion valves (one used when in heating mode and the other when used in cooling mode) and two heat exchangers, one associated with the external heat source/sink and the other with the interior. In heating mode the external heat exchanger is the evaporator and the internal one being the condenser; in cooling mode the roles are reversed.

Circulating refrigerant enters the compressor in the thermodynamic state known as a saturated vapor[65] and is compressed to a higher pressure, resulting in a higher temperature as well. The hot, compressed vapor is then in the thermodynamic state known as a superheated vapor and it is at a temperature and pressure at which it can be condensed with either cooling water or cooling air flowing across the coil or tubes. In heating mode this heat is used to heat the building using the internal heat exchanger, and in cooling mode this heat is rejected via the external heat exchanger.

The condensed, liquid refrigerant, in the thermodynamic state known as a saturated liquid, is next routed through an expansion valve where it undergoes an abrupt reduction in pressure. That pressure reduction results in the adiabatic flash evaporation of a part of the liquid refrigerant. The auto-refrigeration effect of the adiabatic flash evaporation lowers the temperature of the liquid and-vapor refrigerant mixture to where it is colder than the temperature of the enclosed space to be refrigerated.

The cold mixture is then routed through the coil or tubes in the evaporator. A fan circulates the warm air in the enclosed space across the coil or tubes carrying the cold refrigerant liquid and vapor mixture. That warm air evaporates the liquid part of the cold refrigerant mixture. At the same time, the circulating air is cooled and thus lowers the temperature of the enclosed space to the desired temperature. The evaporator is where the circulating refrigerant absorbs and removes heat which is subsequently rejected in the condenser and transferred elsewhere by the water or air used in the condenser.

To complete the refrigeration cycle, the refrigerant vapor from the evaporator is again a saturated vapor and is routed back into the compressor.

Over time, the evaporator may collect ice or water from ambient humidity. The ice is melted through defrosting cycle. An internal heat exchanger is either used to heat/cool the interior air directly or to heat water that is then circulated through radiators or underfloor heating circuit to either heat or cool the buildings.

Improvement of coefficient of performance by subcooling

[edit]

Heat input can be improved if the refrigerant enters the evaporator with a lower vapor content. This can be achieved by cooling the liquid refrigerant after condensation. The gaseous refrigerant condenses on the heat exchange surface of the condenser. To achieve a heat flow from the gaseous flow center to the wall of the condenser, the temperature of the liquid refrigerant must be lower than the condensation temperature.

Additional subcooling can be achieved by heat exchange between relatively warm liquid refrigerant leaving the condenser and the cooler refrigerant vapor emerging from the evaporator. The enthalpy difference required for the subcooling leads to the superheating of the vapor drawn into the compressor. When the increase in cooling achieved by subcooling is greater that the compressor drive input required to overcome the additional pressure losses, such a heat exchange improves the coefficient of performance.[66]

One disadvantage of the subcooling of liquids is that the difference between the condensing temperature and the heat-sink temperature must be larger. This leads to a moderately high pressure difference between condensing and evaporating pressure, whereby the compressor energy increases.[citation needed]

Refrigerant choice

[edit]

Pure refrigerants can be divided into organic substances (hydrocarbons (HCs), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), and HCFOs), and inorganic substances (ammonia (NH
3
), carbon dioxide (CO
2
), and water (H
2O
)[67]).[68] Their boiling points are usually below −25 °C.[69]

In the past 200 years, the standards and requirements for new refrigerants have changed. Nowadays low global warming potential (GWP) is required, in addition to all the previous requirements for safety, practicality, material compatibility, appropriate atmospheric life,[clarification needed] and compatibility with high-efficiency products. By 2022, devices using refrigerants with a very low GWP still have a small market share but are expected to play an increasing role due to enforced regulations,[70] as most countries have now ratified the Kigali Amendment to ban HFCs.[71] Isobutane (R600A) and propane (R290) are far less harmful to the environment than conventional hydrofluorocarbons (HFC) and are already being used in air-source heat pumps.[72] Propane may be the most suitable for high temperature heat pumps.[73] Ammonia (R717) and carbon dioxide (R-744) also have a low GWP. As of 2023 smaller CO
2
heat pumps are not widely available and research and development of them continues.[74] A 2024 report said that refrigerants with GWP are vulnerable to further international restrictions.[75]

Until the 1990s, heat pumps, along with fridges and other related products used chlorofluorocarbons (CFCs) as refrigerants, which caused major damage to the ozone layer when released into the atmosphere. Use of these chemicals was banned or severely restricted by the Montreal Protocol of August 1987.[76]

Replacements, including R-134a and R-410A, are hydrofluorocarbons (HFC) with similar thermodynamic properties with insignificant ozone depletion potential (ODP) but had problematic GWP.[77] HFCs are powerful greenhouse gases which contribute to climate change.[78][79] Dimethyl ether (DME) also gained in popularity as a refrigerant in combination with R404a.[80] More recent refrigerants include difluoromethane (R32) with a lower GWP, but still over 600.

refrigerant 20-year GWP 100-year GWP
R-290 propane[81] 0.072 0.02
R-600a isobutane   3[82]
R-32[81] 491 136
R-410a[83] 4705 2285
R-134a[83] 4060 1470
R-404a[83] 7258 4808

Devices with R-290 refrigerant (propane) are expected to play a key role in the future.[73][84] The 100-year GWP of propane, at 0.02, is extremely low and is approximately 7000 times less than R-32. However, the flammability of propane requires additional safety measures: the maximum safe charges have been set significantly lower than for lower flammability refrigerants (only allowing approximately 13.5 times less refrigerant in the system than R-32).[85][86][87] This means that R-290 is not suitable for all situations or locations. Nonetheless, by 2022, an increasing number of devices with R-290 were offered for domestic use, especially in Europe.[citation needed]

At the same time,[when?] HFC refrigerants still dominate the market. Recent government mandates have seen the phase-out of R-22 refrigerant. Replacements such as R-32 and R-410A are being promoted as environmentally friendly but still have a high GWP.[88] A heat pump typically uses 3 kg of refrigerant. With R-32 this amount still has a 20-year impact equivalent to 7 tons of CO2, which corresponds to two years of natural gas heating in an average household. Refrigerants with a high ODP have already been phased out.[citation needed]

Government incentives

[edit]

Financial incentives aim to protect consumers from high fossil gas costs and to reduce greenhouse gas emissions,[89] and are currently available in more than 30 countries around the world, covering more than 70% of global heating demand in 2021.[4]

Australia

[edit]

Food processors, brewers, petfood producers and other industrial energy users are exploring whether it is feasible to use renewable energy to produce industrial-grade heat. Process heating accounts for the largest share of onsite energy use in Australian manufacturing, with lower-temperature operations like food production particularly well-suited to transition to renewables.

To help producers understand how they could benefit from making the switch, the Australian Renewable Energy Agency (ARENA) provided funding to the Australian Alliance for Energy Productivity (A2EP) to undertake pre-feasibility studies at a range of sites around Australia, with the most promising locations advancing to full feasibility studies.[90]

In an effort to incentivize energy efficiency and reduce environmental impact, the Australian states of Victoria, New South Wales, and Queensland have implemented rebate programs targeting the upgrade of existing hot water systems. These programs specifically encourage the transition from traditional gas or electric systems to heat pump based systems.[91][92][93][94][95]

Canada

[edit]

In 2022, the Canada Greener Homes Grant[96] provides up to $5000 for upgrades (including certain heat pumps), and $600 for energy efficiency evaluations.

China

[edit]

Purchase subsidies in rural areas in the 2010s reduced burning coal for heating, which had been causing ill health.[97]

In the 2024 report by the International Energy Agency (IEA) titled "The Future of Heat Pumps in China," it is highlighted that China, as the world's largest market for heat pumps in buildings, plays a critical role in the global industry. The country accounts for over one-quarter of global sales, with a 12% increase in 2023 alone, despite a global sales dip of 3% the same year.[98]

Heat pumps are now used in approximately 8% of all heating equipment sales for buildings in China as of 2022, and they are increasingly becoming the norm in central and southern regions for both heating and cooling. Despite their higher upfront costs and relatively low awareness, heat pumps are favored for their energy efficiency, consuming three to five times less energy than electric heaters or fossil fuel-based solutions. Currently, decentralized heat pumps installed in Chinese buildings represent a quarter of the global installed capacity, with a total capacity exceeding 250 GW, which covers around 4% of the heating needs in buildings.[98]

Under the Announced Pledges Scenario (APS), which aligns with China's carbon neutrality goals, the capacity is expected to reach 1,400 GW by 2050, meeting 25% of heating needs. This scenario would require an installation of about 100 GW of heat pumps annually until 2050. Furthermore, the heat pump sector in China employs over 300,000 people, with employment numbers expected to double by 2050, underscoring the importance of vocational training for industry growth. This robust development in the heat pump market is set to play a significant role in reducing direct emissions in buildings by 30% and cutting PM2.5 emissions from residential heating by nearly 80% by 2030.[98][99]

European Union

[edit]

To speed up the deployment rate of heat pumps, the European Commission launched the Heat Pump Accelerator Platform in November 2024.[100] It will encourage industry experts, policymakers, and stakeholders to collaborate, share best practices and ideas, and jointly discuss measures that promote sustainable heating solutions.[101]

United Kingdom

[edit]

Until 2027 fixed heat pumps have no Value Added Tax (VAT).[102] As of 2022 the installation cost of a heat pump is more than a gas boiler, but with the "Boiler Upgrade Scheme"[103] government grant and assuming electricity/gas costs remain similar their lifetime costs would be similar on average.[104] However lifetime cost relative to a gas boiler varies considerably depending on several factors, such as the quality of the heat pump installation and the tariff used.[105] In 2024 England was criticised for still allowing new homes to be built with gas boilers, unlike some other counties where this is banned.[106]

United States

[edit]

The High-efficiency Electric Home Rebate Program was created in 2022 to award grants to State energy offices and Indian Tribes in order to establish state-wide high-efficiency electric-home rebates. Effective immediately, American households are eligible for a tax credit to cover the costs of buying and installing a heat pump, up to $2,000. Starting in 2023, low- and moderate-level income households will be eligible for a heat-pump rebate of up to $8,000.[107]

In 2022, more heat pumps were sold in the United States than natural gas furnaces.[108]

In November 2023 Biden's administration allocated 169 million dollars from the Inflation Reduction Act to speed up production of heat pumps. It used the Defense Production Act to do so, because according to the administration, energy that is better for the climate is also better for national security.[109]

Notes

[edit]
  1. ^ As explained in Coefficient of performance TheoreticalMaxCOP = (desiredIndoorTempC + 273) ÷ (desiredIndoorTempC - outsideTempC) = (7+273) ÷ (7 - (-3)) = 280÷10 = 28 [10]
  2. ^ As explained in Coefficient of performance TheoreticalMaxCOP = (desiredIndoorTempC + 273) ÷ (desiredIndoorTempC - outsideTempC) = (27+273) ÷ (27 - (-3)) = 300÷30 = 10[10]

References

[edit]
  1. ^ "Heat Pump Systems". Energy.gov. Retrieved 26 March 2024.
  2. ^ "Gas boiler vs heat pump: which is right for you? - British Gas". www.britishgas.co.uk. Retrieved 18 January 2025.
  3. ^ "Exhaust air heat pumps". Energy Saving Trust. Retrieved 22 February 2024.
  4. ^ a b c d e f g h i Technology Report: The Future of Heat Pumps. International Energy Agency (Report). November 2022. Archived from the original on 6 January 2023. Retrieved 6 January 2023. License: CC BY 4.0.
  5. ^ IPCC AR6 WG3 Ch11 2022, Sec. 11.3.4.1.
  6. ^ IPCC SR15 Ch2 2018, p. 142.
  7. ^ Everitt, Neil (11 September 2023). "Study proves heat pump efficiency at low temperatures". Cooling Post. Retrieved 22 January 2024.
  8. ^ Deetjen, Thomas A.; Walsh, Liam; Vaishnav, Parth (28 July 2021). "US residential heat pumps: the private economic potential and its emissions, health, and grid impacts". Environmental Research Letters. 16 (8): 084024. Bibcode:2021ERL....16h4024D. doi:10.1088/1748-9326/ac10dc. ISSN 1748-9326. S2CID 236486619.
  9. ^ a b G. F. C. Rogers and Y. R. Mayhew (1957), Engineering Thermodynamics, Work and Heat Transfer, Section 13.1, Longmans, Green & Company Limited.
  10. ^ a b "Is there some theoretical maximum coefficient of performance (COP) for heat pumps and chillers?". Physics Stack Exchange. Retrieved 22 February 2024.
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Sources

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IPCC reports

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Other

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  • Media related to Heat pumps at Wikimedia Commons

 

Frequently Asked Questions

Common signs of a clogged ventilation system include reduced airflow from vents, unusual noises such as whistling or rattling, uneven heating or cooling throughout spaces, increased energy bills due to system inefficiency, and unpleasant odors indicating trapped dust or debris.
For minor clogs, first turn off your HVAC system. Then remove any accessible vent covers and use a vacuum cleaner with a hose attachment to clear out visible dust and debris. Ensure you also check air filters; if they appear dirty or clogged, replace them promptly. Reattach any removed components before restarting the system.
Call a professional if you detect persistent clogs after basic cleaning efforts, notice significant temperature imbalances across rooms, hear loud or unusual noises from ducts not resolved by clearing visible blockages, or suspect mold growth within the ductwork which requires specialized cleaning techniques.