Understanding Short Cycling and Its Impact on HVAC Efficiency

Understanding Short Cycling and Its Impact on HVAC Efficiency

air handler maintenance

Short cycling is a term that often surfaces in discussions about HVAC systems, and understanding its causes is crucial for maintaining efficiency and prolonging the life of these systems. At its core, short cycling refers to the frequent turning on and off of an HVAC unit, which can lead to inefficiencies and increased wear and tear. There are several common causes of short cycling that homeowners and facility managers should be aware of.


Older systems often require thermostat replacement so your HVAC system operates at peak efficiency..

One of the primary causes is an improperly sized HVAC system. If the system is too large for the space it serves, it will heat or cool the area too quickly, causing it to shut off prematurely. This rapid cycle not only fails to maintain a consistent temperature but also increases energy consumption as the system constantly powers up and down. Conversely, a system that is too small may run continuously without adequately conditioning the space, leading to other forms of inefficiency.


Thermostat issues are another frequent culprit behind short cycling. A malfunctioning thermostat may inaccurately read room temperatures or have improper settings that cause miscommunication with the HVAC unit. For instance, if a thermostat is located in an area with poor air circulation or direct sunlight exposure, it might signal incorrect temperature readings back to the system.


Additionally, refrigerant leaks within an air conditioning unit can lead to short cycling. When refrigerant levels are low due to leaks, pressure imbalances occur within the system. These imbalances trigger safety mechanisms that cause the unit to turn off prematurely in order to prevent damage.


Dirty or clogged air filters also play a significant role in causing short cycling. When filters are not regularly cleaned or replaced, they restrict airflow through the HVAC system. This restriction forces the system to work harder than necessary, leading it to overheat and shut down intermittently as a protective measure.


Finally, electrical problems such as faulty wiring or connections can result in inconsistent power supply, prompting irregular operation cycles in HVAC units. Regular maintenance checks can help identify these issues before they lead to more severe damage or costly repairs.


Understanding these common causes of short cycling allows individuals to take proactive measures in maintaining their HVAC systems effectively. Ensuring proper sizing during installation, keeping thermostats well-calibrated and positioned correctly, checking refrigerant levels regularly, replacing air filters routinely, and inspecting electrical components can significantly enhance efficiency while minimizing operational disruptions caused by short cycling. By addressing these factors head-on, one can ensure optimal performance from their HVAC systems throughout their operational lifespan.

Short cycling is a term that frequently arises in discussions about HVAC systems, yet its implications are often underestimated by homeowners and even some professionals. Understanding short cycling and its impact on HVAC efficiency is crucial for ensuring optimal performance and longevity of heating, ventilation, and air conditioning systems.


At its core, short cycling refers to the condition where an HVAC system turns on and off more frequently than it should. This erratic operation can be caused by various factors, including incorrectly sized units, thermostat malfunctions, or issues with airflow. Regardless of the root cause, the effect remains consistent: reduced efficiency and increased wear on the system.


One of the primary ways short cycling affects HVAC efficiency is through energy consumption. Each time an HVAC unit powers up, it requires a significant amount of energy to start. If this cycle repeats too often within a short timeframe, it results in excessive energy usage compared to a system running in longer, more stable cycles. Consequently, homeowners may notice a spike in their energy bills without any improvement in comfort levels.


Moreover, frequent starting and stopping put additional stress on the mechanical components of the HVAC system. Motors, compressors, and other parts endure increased wear and tear due to constant operation changes. This not only reduces the lifespan of these components but can also lead to unexpected breakdowns requiring costly repairs or replacements.


Comfort within living spaces can also be compromised due to short cycling. When an HVAC system fails to complete a full cycle efficiently, it may struggle to maintain consistent temperatures throughout the home. Some areas might remain too warm or too cold as the system isn't running long enough to distribute air evenly.


Furthermore, short cycling can contribute to poor humidity control. During normal operation cycles, air conditioners dehumidify indoor air effectively. However, if they shut down prematurely due to short cycling tendencies, they may not run long enough to remove adequate moisture from the air. This can leave homes feeling clammy or stuffy-a discomfort that could have been avoided with proper functioning.


Addressing short cycling involves identifying its underlying causes and implementing appropriate solutions. Ensuring that an HVAC system is correctly sized for the property is paramount; oversized units tend to cool or heat spaces too quickly before shutting off prematurely-a common trigger for short cycling scenarios. Regular maintenance checks help identify issues like clogged filters or blocked vents that could impede airflow leading again towards undesired operational patterns.


In conclusion understanding how short cycling impacts HVAC efficiency underscores importance taking proactive measures maintain properly functioning systems while preserving both comfort cost-effectiveness within households being mindful potential problems addressing them early prevent escalation into larger issues down road ultimately benefits everyone involved making informed decisions about care management heating cooling installations essential achieving balance between functionality sustainability achieving peace mind knowing environment adequately controlled without unnecessary expenses incurred along way .

Citations and other links

The Role of Annual HVAC Maintenance in Preventing Short Cycling

The Role of Annual HVAC Maintenance in Preventing Short Cycling


Understanding the intricacies of an HVAC system is crucial to ensuring its efficiency and longevity. Among the various issues that can plague these systems, short cycling stands out as a particularly detrimental problem. Short cycling occurs when an HVAC system turns on and off more frequently than it should, preventing the system from completing a full cooling or heating cycle. This not only hampers the system's efficiency but also accelerates wear and tear, leading to higher energy bills and potentially costly repairs.


Annual HVAC maintenance plays a pivotal role in preventing short cycling and ensuring that your system runs smoothly throughout its lifespan. By scheduling regular check-ups with a qualified technician, homeowners can catch potential issues before they escalate into something more serious. During these routine inspections, technicians will examine various components of the HVAC system such as filters, thermostats, and electrical connections to ensure everything is functioning correctly.


One common cause of short cycling is a clogged or dirty air filter. When air filters are not replaced regularly, they become obstructed with dust and debris, restricting airflow within the system. This lack of proper airflow forces the HVAC unit to work harder to reach the desired temperature, causing it to turn on and off more frequently. Regular maintenance includes replacing or cleaning these filters as needed, significantly reducing the risk of short cycling.


Another potential culprit behind short cycling is an incorrectly sized HVAC unit for your home's needs. If a unit is too large for the space it serves, it will heat or cool too quickly without adequately dehumidifying or evenly distributing air throughout your home. Consequently, this leads to frequent on-and-off cycles. During annual maintenance visits, technicians assess whether your current unit meets your home's requirements effectively and suggest appropriate solutions if discrepancies are found.


Thermostat malfunctions also contribute to short cycling problems. A faulty thermostat may inaccurately read temperatures or be placed in an area that does not accurately reflect room conditions (such as near windows or direct sunlight). Technicians routinely calibrate thermostats during inspections to ensure accurate readings that prevent unnecessary cycle fluctuations.


In summary, annual HVAC maintenance acts as both a preventive measure against short cycling and an overall strategy for maintaining peak performance levels within heating and cooling systems. By investing time into yearly inspections conducted by experienced professionals who understand each component's role within larger machinery structures; homeowners stand poised against premature breakdowns while simultaneously optimizing operational efficiencies-ultimately saving money over time through reduced utility costs alongside minimized repair expenditures thanks largely imparted due diligence shown via consistent upkeep efforts!

The Role of Annual HVAC Maintenance in Preventing Short Cycling
Steps for Identifying and Diagnosing Short Cycling Issues

Steps for Identifying and Diagnosing Short Cycling Issues

Short cycling is a common issue that can significantly affect the efficiency of HVAC systems. It refers to the problem where an HVAC system turns on and off more frequently than necessary, failing to complete a full heating or cooling cycle. This not only reduces the efficiency of the system but also increases wear and tear, leading to higher maintenance costs and potentially shortening the lifespan of the equipment.


To effectively identify and diagnose short cycling issues, one must follow a series of methodical steps. The first step involves keen observation. Homeowners or technicians should monitor the HVAC system for signs of short cycling, such as unusually frequent starts and stops or rooms not reaching their desired temperatures consistently.


Once short cycling is suspected, it's important to check the thermostat settings. An improperly set thermostat can cause the system to turn on and off erratically. Ensuring that it is calibrated correctly and positioned away from direct sunlight or drafts helps in providing accurate temperature readings.


Next, inspect airflow throughout the system. Blocked air filters are a common culprit behind short cycling because they restrict airflow, causing the system to overheat and shut down prematurely. Regularly replacing air filters ensures optimal airflow, reducing strain on the system.




Understanding Short Cycling and Its Impact on HVAC Efficiency - indoor air quality

  1. air handler maintenance
  2. indoor air quality
  3. condenser unit repair

Another critical step is examining refrigerant levels in air conditioning units or heat pumps. Low refrigerant levels can lead to pressure imbalances within the system, triggering short cycles as safety mechanisms kick in to prevent damage. A professional technician should be engaged to check refrigerant levels and address any leaks if detected.


Moreover, evaluate whether your HVAC unit is appropriately sized for your space. Systems that are too large for their environment will cool or heat spaces too quickly, leading them to constantly turn on and off without completing full cycles. Consulting with an HVAC specialist can help determine if resizing is necessary.


Lastly, consider inspecting electrical components like capacitors and relays within your HVAC unit. Faulty electrical parts might cause irregular operation patterns affecting cycle duration. Technicians should conduct thorough checks during routine maintenance visits to ensure all components are functioning properly.


In conclusion, identifying and diagnosing short cycling issues require a systematic approach involving observation, inspection of key components like thermostats and filters, assessment of refrigerant levels, checking system sizing appropriateness, and regular maintenance of electrical elements. Addressing these factors not only enhances HVAC efficiency but also prolongs its lifespan while ensuring comfort within living spaces remains uncompromised.

Best Practices for Maintaining Optimal HVAC Performance

Maintaining optimal HVAC performance is crucial for both energy efficiency and the longevity of the system.

Understanding Short Cycling and Its Impact on HVAC Efficiency - air handler maintenance

  1. geothermal heating and cooling
  2. duct cleaning
  3. boiler maintenance
One key issue that can significantly impact HVAC efficiency is short cycling, a condition where the system turns on and off frequently without completing a full heating or cooling cycle. Understanding short cycling and its implications is essential for anyone looking to improve their HVAC system's performance.


Short cycling typically occurs when an HVAC system is oversized or malfunctioning, leading it to reach the desired temperature too quickly and shut off prematurely. This constant stopping and starting not only wastes energy but can also cause wear and tear on the system components, ultimately reducing the unit's lifespan. Moreover, short cycling prevents the even distribution of air throughout a space, leading to hot and cold spots which diminish overall comfort.


One of the primary culprits behind short cycling is an improperly sized unit. An oversized HVAC system will achieve targeted temperatures swiftly but inefficiently, as it lacks time to dehumidify air properly or distribute it evenly throughout a building. This problem underscores the importance of professional assessments during installations; ensuring that your system is appropriately sized for your space can prevent many issues down the line.


Thermostat malfunctions are another common cause of short cycling. A faulty thermostat might misread indoor temperatures, prompting unnecessary starts and stops. Regular maintenance checks can help identify such issues early on. Recalibrating or replacing thermostats when needed ensures accurate readings and helps maintain consistent indoor climates without overworking your HVAC system.


Dirty filters also contribute to short cycling by restricting airflow, causing the unit to overheat and shut off as a safety measure. Routine filter changes are among the simplest yet most effective practices in maintaining optimal HVAC performance. Clean filters facilitate smooth airflow, enabling systems to operate more efficiently while improving indoor air quality.


Additionally, inspecting refrigerant levels is vital in preventing short cycling in air conditioning units. Low refrigerant levels mean that systems struggle to achieve desired temperatures, causing them to overwork themselves into frequent cycles. Annual check-ups with HVAC professionals should include refrigerant level evaluations to ensure they meet manufacturer specifications.


Preventative maintenance plays a pivotal role in combating short cycling and enhancing overall efficiency. Scheduling regular inspections allows professionals to detect potential problems before they escalate into severe issues requiring costly repairs or replacements.


In conclusion, understanding short cycling helps highlight why certain best practices are crucial for maintaining peak HVAC performance: ensuring correct unit sizing during installation; conducting routine maintenance including filter changes; checking thermostat functionality; monitoring refrigerant levels; and committing to annual professional inspections all contribute significantly towards achieving an efficient, reliable heating and cooling solution that stands up against time's relentless march forward while maximizing comfort within homes or businesses alike through effective prevention strategies geared specifically toward addressing this prevalent issue head-on today!

Best Practices for Maintaining Optimal HVAC Performance
Long-Term Benefits of Regular Maintenance on System Longevity and Energy Savings

In the realm of HVAC systems, efficiency and longevity are paramount. These complex systems, integral to maintaining comfort in both residential and commercial spaces, require consistent care and attention. One phenomenon that significantly impacts HVAC efficiency is short cycling, a condition where the system turns on and off frequently without completing a full heating or cooling cycle.

Understanding Short Cycling and Its Impact on HVAC Efficiency - indoor air quality

  1. geothermal heating and cooling
  2. duct cleaning
  3. boiler maintenance
Understanding short cycling is crucial because it not only compromises system efficiency but also accelerates wear and tear, potentially leading to costly repairs or even premature replacement.


Regular maintenance serves as a preventive measure against short cycling, offering long-term benefits that extend the lifespan of HVAC systems while promoting energy savings. When an HVAC system is well-maintained, it operates closer to its optimal performance level. This involves routine checks and services such as cleaning filters, inspecting ductwork for leaks, calibrating thermostats, and ensuring refrigerant levels are adequate. Each of these tasks contributes to preventing short cycling by addressing common underlying causes such as clogged filters or incorrect thermostat settings.


The impact of regular maintenance goes beyond simply preventing operational issues; it enhances system longevity. By keeping components clean and in good working order, maintenance reduces the strain on critical parts like compressors and motors. A well-maintained system experiences less friction and overheating-common precursors to mechanical failure-and thus can serve its intended lifespan without frequent breakdowns.


Energy savings are another compelling benefit of regular HVAC maintenance. Short cycling often results in increased energy consumption because the system uses more power during start-ups than during continuous operation. By ensuring components function efficiently through regular upkeep, homeowners and businesses alike can enjoy lower utility bills. In fact, studies suggest that properly maintained HVAC systems consume 15-20% less energy compared to neglected ones.


Moreover, with energy conservation being a global priority due to environmental concerns and rising costs, maintaining an efficient HVAC system aligns with broader sustainability goals. Reducing energy consumption not only lowers individual expenses but also decreases overall demand on power grids, contributing positively to environmental stewardship efforts.


In conclusion, understanding short cycling reveals the critical role regular maintenance plays in enhancing HVAC efficiency. The long-term benefits are multifaceted: improved system longevity reduces replacement costs; enhanced operational efficiency yields significant energy savings; and a reduced carbon footprint supports global environmental initiatives. Therefore, investing time and resources into regular maintenance should be viewed not merely as an option but as an essential practice for anyone relying on HVAC systems for comfort year-round. Through this proactive approach, homeowners and businesses ensure their systems remain reliable allies in creating comfortable living and working environments while optimizing operational costs over time.

Geothermal heating

Geothermal heating is the direct use of geothermal energy for some heating applications. Humans have taken advantage of geothermal heat this way since the Paleolithic era. Approximately seventy countries made direct use of a total of 270 PJ of geothermal heating in 2004. As of 2007, 28 GW of geothermal heating capacity is installed around the world, satisfying 0.07% of global primary energy consumption.[1] Thermal efficiency is high since no energy conversion is needed, but capacity factors tend to be low (around 20%) since the heat is mostly needed in the winter.

Geothermal energy originates from the heat retained within the Earth since the original formation of the planet, from radioactive decay of minerals, and from solar energy absorbed at the surface.[2] Most high temperature geothermal heat is harvested in regions close to tectonic plate boundaries where volcanic activity rises close to the surface of the Earth. In these areas, ground and groundwater can be found with temperatures higher than the target temperature of the application. However, even cold ground contains heat. Below 6 metres (20 ft), the undisturbed ground temperature is consistently at the mean annual air temperature,[3] and this heat can be extracted with a ground source heat pump.

Applications

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Top countries using the most geothermal heating in 2005[4]
Country Production
PJ/yr
Capacity
GW
Capacity
factor
Dominant
applications
China 45.38 3.69 39% bathing
Sweden 43.2 4.2 33% heat pumps
USA 31.24 7.82 13% heat pumps
Turkey 24.84 1.5 53% district heating
Iceland 24.5 1.84 42% district heating
Japan 10.3 0.82 40% bathing (onsens)
Hungary 7.94 0.69 36% spas/greenhouses
Italy 7.55 0.61 39% spas/space heating
New Zealand 7.09 0.31 73% industrial uses
63 others 71 6.8    
Total 273 28 31% space heating
Direct use of geothermal heat by category in 2015 as adapted from John W. Lund [5]
Category GWh/year
Geothermal heat pumps 90,293
Bathing and swimming 33,164
Space heating 24,508
Greenhouse heating 7,407
Aquaculture pond heating 3,322
Industrial uses 2,904
Cooling/snow melting 722
Agriculture drying 564
Others 403
Total 163,287

There are a wide variety of applications for cheap geothermal heat including heating of houses, greenhouses, bathing and swimming or industrial uses. Most applications use geothermal in the form of hot fluids between 50 °C (122 °F) and 150 °C (302 °F). The suitable temperature varies for the different applications. For direct use of geothermal heat, the temperature range for the agricultural sector lies between 25 °C (77 °F) and 90 °C (194 °F), for space heating lies between 50 °C (122 °F) to 100 °C (212 °F).[4] Heat pipes extend the temperature range down to 5 °C (41 °F) as they extract and "amplify" the heat. Geothermal heat exceeding 150 °C (302 °F) is typically used for geothermal power generation.[6]

In 2004 more than half of direct geothermal heat was used for space heating, and a third was used for spas.[1] The remainder was used for a variety of industrial processes, desalination, domestic hot water, and agricultural applications. The cities of Reykjavík and Akureyri pipe hot water from geothermal plants under roads and pavements to melt snow. Geothermal desalination has been demonstrated.

Geothermal systems tend to benefit from economies of scale, so space heating power is often distributed to multiple buildings, sometimes whole communities. This technique, long practiced throughout the world in locations such as Reykjavík, Iceland;[7] Boise, Idaho;[8] and Klamath Falls, Oregon;[9] is known as district heating.[10]

In Europe alone 280 geothermal district heating plants were in operation in 2016 according to the European Geothermal Energy Council (EGEC) with a total capacity of approximately 4.9 GWth.[11]

Extraction

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Some parts of the world, including substantial portions of the western USA, are underlain by relatively shallow geothermal resources.[12] Similar conditions exist in Iceland, parts of Japan, and other geothermal hot spots around the world. In these areas, water or steam may be captured from natural hot springs and piped directly into radiators or heat exchangers. Alternatively, the heat may come from waste heat supplied by co-generation from a geothermal electrical plant or from deep wells into hot aquifers. Direct geothermal heating is far more efficient than geothermal electricity generation and has less demanding temperature requirements, so it is viable over a large geographical range. If the shallow ground is hot but dry, air or water may be circulated through earth tubes or downhole heat exchangers which act as heat exchangers with the ground.

Steam under pressure from deep geothermal resources is also used to generate electricity from geothermal power. The Iceland Deep Drilling Project struck a pocket of magma at 2,100m. A cemented steelcase was constructed in the hole with a perforation at the bottom close to the magma. The high temperatures and pressure of the magma steam were used to generate 36MW of electricity, making IDDP-1 the world's first magma-enhanced geothermal system.[13]

In areas where the shallow ground is too cold to provide comfort directly, it is still warmer than the winter air. The thermal inertia of the shallow ground retains solar energy accumulated in the summertime, and seasonal variations in ground temperature disappear completely below 10m of depth. That heat can be extracted with a geothermal heat pump more efficiently than it can be generated by conventional furnaces.[10] Geothermal heat pumps are economically viable essentially anywhere in the world.

In theory, geothermal energy (usually cooling) can also be extracted from existing infrastructure, such as municipal water pipes.[14]

Ground-source heat pumps

[edit]

In regions without any high temperature geothermal resources, a ground-source heat pump (GSHP) can provide space heating and space cooling. Like a refrigerator or air conditioner, these systems use a heat pump to force the transfer of heat from the ground to the building. Heat can be extracted from any source, no matter how cold, but a warmer source allows higher efficiency. A ground-source heat pump uses the shallow ground or ground water (typically starting at 10–12 °C or 50–54 °F) as a source of heat, thus taking advantage of its seasonally moderate temperatures.[15] In contrast, an air source heat pump draws heat from the air (colder outside air) and thus requires more energy.

GSHPs circulate a carrier fluid (usually a mixture of water and small amounts of antifreeze) through closed pipe loops buried in the ground. Single-home systems can be "vertical loop field" systems with bore holes 50–400 feet (15–120 m) deep or,[16] if adequate land is available for extensive trenches, a "horizontal loop field" is installed approximately six feet subsurface. As the fluid circulates underground it absorbs heat from the ground and, on its return, the warmed fluid passes through the heat pump which uses electricity to extract heat from the fluid. The re-chilled fluid is sent back into the ground thus continuing the cycle. The heat extracted and that generated by the heat pump appliance as a byproduct is used to heat the house. The addition of the ground heating loop in the energy equation means that significantly more heat can be transferred to a building than if electricity alone had been used directly for heating.

Switching the direction of heat flow, the same system can be used to circulate the cooled water through the house for cooling in the summer months. The heat is exhausted to the relatively cooler ground (or groundwater) rather than delivering it to the hot outside air as an air conditioner does. As a result, the heat is pumped across a larger temperature difference and this leads to higher efficiency and lower energy use.[15]

This technology makes ground source heating economically viable in any geographical location. In 2004, an estimated million ground-source heat pumps with a total capacity of 15 GW extracted 88 PJ of heat energy for space heating. Global ground-source heat pump capacity is growing by 10% annually.[1]

History

[edit]
The oldest known pool fed by a hot spring, built in the Qin dynasty in the 3rd century BC

Hot springs have been used for bathing at least since Paleolithic times.[17] The oldest known spa is a stone pool on China's Mount Li built in the Qin dynasty in the 3rd century BC, at the same site where the Huaqing Chi palace was later built. Geothermal energy supplied channeled district heating for baths and houses in Pompeii around 0 AD.[18] In the first century AD, Romans conquered Aquae Sulis in England and used the hot springs there to feed public baths and underfloor heating.[19] The admission fees for these baths probably represents the first commercial use of geothermal power. A 1,000-year-old hot tub has been located in Iceland, where it was built by one of the island's original settlers.[20] The world's oldest working geothermal district heating system in Chaudes-Aigues, France, has been operating since the 14th century.[4] The earliest industrial exploitation began in 1827 with the use of geyser steam to extract boric acid from volcanic mud in Larderello, Italy.

In 1892, America's first district heating system in Boise, Idaho, was powered directly by geothermal energy, and was soon copied in Klamath Falls, Oregon in 1900. A deep geothermal well was used to heat greenhouses in Boise in 1926, and geysers were used to heat greenhouses in Iceland and Tuscany at about the same time.[21] Charlie Lieb developed the first downhole heat exchanger in 1930 to heat his house. Steam and hot water from the geysers began to be used to heat homes in Iceland in 1943.

By this time, Lord Kelvin had already invented the heat pump in 1852, and Heinrich Zoelly had patented the idea of using it to draw heat from the ground in 1912.[22] But it was not until the late 1940s that the geothermal heat pump was successfully implemented. The earliest one was probably Robert C. Webber's home-made 2.2 kW direct-exchange system, but sources disagree as to the exact timeline of his invention.[22] J. Donald Kroeker designed the first commercial geothermal heat pump to heat the Commonwealth Building (Portland, Oregon) and demonstrated it in 1946.[23][24] Professor Carl Nielsen of Ohio State University built the first residential open loop version in his home in 1948.[25] The technology became popular in Sweden as a result of the 1973 oil crisis, and has been growing slowly in worldwide acceptance since then. The 1979 development of polybutylene pipe greatly augmented the heat pump's economic viability.[23] Since 2000, a compelling body of research has been dedicated to numerically evidence the advantages and efficiency of using CO2, alternative to water, as heat transmission fluid for geothermal energy recovery from enhanced geothermal systems (EGS) where the permeability of the underground source is enhanced by hydrofracturing.[26][27] As of 2004, there are over one million geothermal heat pumps installed worldwide providing 12 GW of thermal capacity.[28] Each year, about 80,000 units are installed in the US and 27,000 in Sweden.[28]

Economics

[edit]
Geothermal drill machine

Geothermal energy is a type of renewable energy that encourages conservation of natural resources. According to the US Environmental Protection Agency, geo-exchange systems save homeowners 30–70 percent in heating costs, and 20–50 percent in cooling costs, compared to conventional systems.[29] Geo-exchange systems also save money because they require much less maintenance. In addition to being highly reliable they are built to last for decades.

Some utilities, such as Kansas City Power and Light, offer special, lower winter rates for geothermal customers, offering even more savings.[15]

Geothermal drilling risks

[edit]
Cracks at the historic Town Hall of Staufen im Breisgau presumed due to damage from geothermal drilling

In geothermal heating projects the underground is penetrated by trenches or drillholes. As with all underground work, projects may cause problems if the geology of the area is poorly understood.

In the spring of 2007 an exploratory geothermal drilling operation was conducted to provide geothermal heat to the town hall of Staufen im Breisgau. After initially sinking a few millimeters, a process called subsidence,[30] the city center has started to rise gradually[31] causing considerable damage to buildings in the city center, affecting numerous historic houses including the town hall. It is hypothesized that the drilling perforated an anhydrite layer bringing high-pressure groundwater to come into contact with the anhydrite, which then began to expand. Currently no end to the rising process is in sight.[32][33][34] Data from the TerraSAR-X radar satellite before and after the changes confirmed the localised nature of the situation:

A geochemical process called anhydrite swelling has been confirmed as the cause of these uplifts. This is a transformation of the mineral anhydrite (anhydrous calcium sulphate) into gypsum (hydrous calcium sulphate). A pre-condition for this transformation is that the anhydrite is in contact with water, which is then stored in its crystalline structure.[35] There are other sources of potential risks, i.e.: cave enlargement or worsening of stability conditions, quality or quantity degradation of groundwater resources, Specific hazard worsening in the case of landslide-prone areas, worsening of rocky mechanical characteristics, soil and water pollution (i.e. due to antifreeze additives or polluting constructive and boring material).[36] The design defined on the base of site-specific geological, hydrogeological and environmental knowledge prevent all these potential risks.

See also

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References

[edit]
  1. ^ a b c Fridleifsson, Ingvar B.; Bertani, Ruggero; Huenges, Ernst; Lund, John W.; Ragnarsson, Arni; Rybach, Ladislaus (2008-02-11). "The possible role and contribution of geothermal energy to the mitigation of climate change" (PDF). In O. Hohmeyer; T. Trittin (eds.). Proceedings of the IPCC Scoping Meeting on Renewable Energy Sources. Luebeck, Germany. pp. 59–80. Archived from the original (PDF) on 2017-08-08.
  2. ^ Heat Pumps, Energy Management and Conservation Handbook, 2008, pp. 9–3
  3. ^ Mean Annual Air Temperature
  4. ^ a b c Lund, John W. (June 2007), "Characteristics, Development and utilization of geothermal resources" (PDF), Geo-Heat Centre Quarterly Bulletin, vol. 28, no. 2, Klamath Falls, Oregon: Oregon Institute of Technology, pp. 1–9, ISSN 0276-1084, archived from the original (PDF) on 2010-06-17, retrieved 2009-04-16
  5. ^ Lund, John W. (2015-06-05). "Geothermal Resources Worldwide, Direct Heat Utilization of". Encyclopedia of Sustainability and Technology: 1–29. doi:10.1007/978-1-4939-2493-6_305-3. ISBN 978-1-4939-2493-6.
  6. ^ Hanania, Jordan; Sheardown, Ashley; Stenhouse, Kailyn; Donev, Jason. "Geothermal district heating". Energy education by Prof. Jason Donev and students, University of Calgary. Retrieved 2020-09-18.
  7. ^ "History of the utilization of geothermal sources of energy in Iceland". University of Rochester. Archived from the original on 2012-02-06.
  8. ^ "District Heating Systems in Idaho". Idaho Department of Water Resources. Archived from the original on 2007-01-21.
  9. ^ Brown, Brian.Klamath Falls Geothermal District Heating Systems Archived 2008-01-19 at the Wayback Machine
  10. ^ a b "Geothermal Basics Overview". Office of Energy Efficiency and Renewable Energy. Archived from the original on 2008-10-04. Retrieved 2008-10-01.
  11. ^ "EGEC Geothermal Market Report 2016 Key Findings (Sixth Edition, May 2017)" (PDF). www.egec.org. EGEC - European Geothermal Energy Council. 2017-12-13. p. 9.
  12. ^ What is Geothermal? Archived October 5, 2013, at the Wayback Machine
  13. ^ Wilfred Allan Elders, Guðmundur Ómar Friðleifsson and Bjarni Pálsson (2014). Geothermics Magazine, Vol. 49 (January 2014). Elsevier Ltd.
  14. ^ Tadayon, Saied; Tadayon, Bijan; Martin, David (2012-10-11). "Patent US20120255706 - Heat Exchange Using Underground Water System".
  15. ^ a b c Goswami, Yogi D., Kreith, Frank, Johnson, Katherine (2008), p. 9-4.
  16. ^ "Geothermal Heating and Cooling Systems". Well Management. Minnesota Department of Health. Archived from the original on 2014-02-03. Retrieved 2012-08-25.
  17. ^ Cataldi, Raffaele (August 1993). "Review of historiographic aspects of geothermal energy in the Mediterranean and Mesoamerican areas prior to the Modern Age" (PDF). Geo-Heat Centre Quarterly Bulletin. 15 (1): 13–16. ISSN 0276-1084. Archived from the original (PDF) on 2010-06-18. Retrieved 2009-11-01.
  18. ^ Bloomquist, R. Gordon (2001). Geothermal District Energy System Analysis, Design, and Development (PDF). International Summer School. International Geothermal Association. p. 213(1). Retrieved November 28, 2015. During Roman times, warm water was circulated through open trenches to provide heating for buildings and baths in Pompeii.
  19. ^ "A History of Geothermal Energy in the United States". US Department of Energy, Geothermal Technologies Program. Archived from the original on 2007-09-04. Retrieved 2007-09-10.
  20. ^ "One Hot Island: Iceland's Renewable Geothermal Power". Scientific American.
  21. ^ Dickson, Mary H.; Fanelli, Mario (February 2004). "What is Geothermal Energy?". Pisa, Italy: Istituto di Geoscienze e Georisorse. Archived from the original on 2009-10-09. Retrieved 2009-10-13.
  22. ^ a b Zogg, M. (20–22 May 2008). History of Heat Pumps: Swiss Contributions and International Milestones (PDF). Zürich, Switzerland: 9th International IEA Heat Pump Conference.
  23. ^ a b Bloomquist, R. Gordon (December 1999). "Geothermal Heat Pumps, Four Plus Decades of Experience" (PDF). Geo-Heat Centre Quarterly Bulletin. 20 (4): 13–18. ISSN 0276-1084. Archived from the original (PDF) on 2012-10-31. Retrieved 2009-03-21.
  24. ^ Kroeker, J. Donald; Chewning, Ray C. (February 1948). "A Heat Pump in an Office Building". ASHVE Transactions. 54: 221–238.
  25. ^ Gannon, Robert (February 1978). "Ground-Water Heat Pumps – Home Heating and Cooling from Your Own Well". Popular Science. 212 (2): 78–82. ISSN 0161-7370. Retrieved 2009-11-01.
  26. ^ Brown, D.W. (January 2000). "A Hot Dry Rock Geothermal Energy Concept Utilizing Supercritical CO2 Instead of Water" (PDF). Proceedings of Twenty-Fifth Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, January 24-26, 2000: 233–238.
  27. ^ Atrens, A.D.; Gurgenci, H.; Rudolph, V. (2009). "CO2 Thermosiphon for Competitive Geothermal Power Generation". Energy Fuels. 23 (1): 553–557. doi:10.1021/ef800601z.
  28. ^ a b Lund, J.; Sanner, B.; Rybach, L.; Curtis, R.; Hellström, G. (September 2004). "Geothermal (Ground Source) Heat Pumps, A World Overview" (PDF). Geo-Heat Centre Quarterly Bulletin. 25 (3): 1–10. ISSN 0276-1084. Archived from the original (PDF) on 2014-02-01. Retrieved 2009-03-21.
  29. ^ "Geothermal Heat Pump Consortium, Inc". Retrieved 2008-04-27.
  30. ^ The Telegraph: Geothermal probe sinks German city (March 31, 2008)
  31. ^ Lubbadeh, Jens (15 November 2008). "Eine Stadt zerreißt" [A town rips up]. Spiegel Wissenschaft (in German). Partial translation.
  32. ^ Sass, Ingo; Burbaum, Ulrich (2010). "Damage to the historic town of Staufen (Germany) caused by geothermal drillings through anhydrite-bearing formations". Acta Carsologica. 39 (2): 233. doi:10.3986/ac.v39i2.96.
  33. ^ Butscher, Christoph; Huggenberger, Peter; Auckenthaler, Adrian; Bänninger, Dominik (2010). "Risikoorientierte Bewilligung von Erdwärmesonden" (PDF). Grundwasser. 16 (1): 13–24. Bibcode:2011Grund..16...13B. doi:10.1007/s00767-010-0154-5. S2CID 129598890.
  34. ^ Goldscheider, Nico; Bechtel, Timothy D. (2009). "Editors' message: The housing crisis from underground—damage to a historic town by geothermal drillings through anhydrite, Staufen, Germany". Hydrogeology Journal. 17 (3): 491–493. Bibcode:2009HydJ...17..491G. doi:10.1007/s10040-009-0458-7.
  35. ^ "TerraSAR-X Image Of The Month: Ground Uplift Under Staufen's Old Town". www.spacemart.com. SpaceDaily. 2009-10-22. Retrieved 2009-10-23.
  36. ^ De Giorgio, Giorgio; Chieco, Michele; Limoni, Pier Paolo; Zuffianò, Livia Emanuela; Dragone, Vittoria; Romanazzi, Annarita; Pagliarulo, Rossella; Musicco, Giuseppe; Polemio, Maurizio (2020-10-19). "Improving Regulation and the Role of Natural Risk Knowledge to Promote Sustainable Low Enthalpy Geothermal Energy Utilization". Water. 12 (10): 2925. doi:10.3390/w12102925. ISSN 2073-4441.
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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

[edit]
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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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References

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  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

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Media related to Climate control at Wikimedia Commons

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Frequently Asked Questions

Short cycling refers to the frequent turning on and off of an HVAC system before it completes a full cooling or heating cycle. This can lead to increased wear and tear, reduced efficiency, and higher energy bills.
Short cycling decreases the efficiency of an HVAC system by preventing it from reaching optimal operating temperatures. This results in more frequent starts and stops, which consume more energy and cause unnecessary stress on components.
Annual HVAC maintenance helps prevent short cycling by identifying and addressing issues such as dirty filters, refrigerant leaks, or faulty thermostats that can contribute to this problem. Regular inspections ensure that the system operates smoothly and efficiently throughout its lifecycle.