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.

Do you need expertise in HVAC? Roswell and Marietta residents who choose Moncrief Heating & Air Conditioning get the benefit of over 118 years of reputable experience in air conditioning and furnace repair, service and installation. Whether you have an emergency or need routine service, we are available 365 days a year. Call us today at 404-350-2300.
Designed to improve manufacturing process control in a printing plant, Carrier's invention controlled not only temperature but also humidity. Carrier used his knowledge of the heating of objects with steam and reversed the process. Instead of sending air through hot coils, he sent it through cold coils (filled with cold water). The air was cooled, and thereby the amount of moisture in the air could be controlled, which in turn made the humidity in the room controllable. The controlled temperature and humidity helped maintain consistent paper dimensions and ink alignment. Later, Carrier's technology was applied to increase productivity in the workplace, and The Carrier Air Conditioning Company of America was formed to meet rising demand. Over time, air conditioning came to be used to improve comfort in homes and automobiles as well. Residential sales expanded dramatically in the 1950s.[citation needed]

The first air conditioners and refrigerators employed toxic or flammable gases, such as ammonia, methyl chloride, or propane, that could result in fatal accidents when they leaked. Thomas Midgley, Jr. created the first non-flammable, non-toxic chlorofluorocarbon gas, Freon, in 1928. The name is a trademark name owned by DuPont for any chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC), or hydrofluorocarbon (HFC) refrigerant. The refrigerant names include a number indicating the molecular composition (e.g., R-11, R-12, R-22, R-134A). The blend most used in direct-expansion home and building comfort cooling is an HCFC known as chlorodifluoromethane (R-22).


Installing or replacing central air can be a huge expense, so you’ll want to get it right. To ensure that you have the best advice, we surveyed more than 14,000 Consumer Reports readers about new central air-conditioning systems they bought and installed between 2009 and 2016. We learned how satisfied they were overall with their purchase, the cost of repairs, how many systems break, and which parts break most often.
As this liquid passes through the indoor cooling coil on the inside of the heat exchanger, two things happen to the air that passes over the coil’s surface on the outside of the heat exchanger. The air’s temperature is lowered (sensible cooling) and moisture in the air is removed (latent cooling) if the indoor air dew point is higher than the temperature of the coil’s surface. The total cooling (capacity) of an AC system is the sum of the sensible and latent cooling. Many factors influence the cooling capacity of a DX air conditioner. Total cooling is inversely proportional to outdoor temperature. As the outdoor temperature increases the total capacity is reduced. Air flow over the indoor cooling coil also affects the coil’s capacity and is directly proportional to the total capacity of an AC system. As air flow increases, the total capacity also increases. At higher air flow rates the latent capacity of the cooling coil is reduced. Indoor temperature and humidity also affect the total capacity of the AC system. As indoor temperatures increase, the sensible capacity also increases. Similarly, as indoor relative humidity increases the latent capacity of the AC system increases. Manufacturers of AC equipment typically provide a “performance map” of specific equipment to show how total, sensible, and latent capacity change with changing indoor and outdoor temperatures and humidity. Power consumption and energy efficiency are also provided in these charts.

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As the name implies, a window air conditioner is typically installed in a window or custom opening in a wall. The Window AC can only cool small areas and are not intended to provide cooling to multiple rooms or zones. These air conditioners are manufactured as cool only or can provide both cooling and heating. An optional damper in the unit can provide fresh outdoor air if necessary.
What happens when you have an emergency? The first reaction of most people is to panic. When a furnace stops working, you need it fixed and fixed immediately—especially in the middle of a cold, Ohio winter. That need can make people feel as if they are at the mercy of the repair company. That is why it is so important to call a company you can trust and rely on—Jennings Heating and Cooling.
Refrigerant Metering Device -- Every HVAC system has one of these, and heat pumps have two. They regulate the amount of refrigerant going through your air-conditioner. If it fails, either too much or too little refrigerant will course along the lines and either not perform well or will overwhelm the compressor and cause it to fail. A total failure of this component will result in a complete loss of operation.
We’ve proudly represented the very best Atlanta has to offer in superior service for 50 years. In that time, we’ve accumulated all it takes and more to bring you the best emergency heating and air conditioning repair services possible. Story after story, we deliver smiles! If you’re looking for a reliable company that provides 24-hour AC repair, don’t hesitate to contact us right away—770-913-6412!
Absorption refrigerator Air barrier Air conditioning Antifreeze Automobile air conditioning Autonomous building Building insulation materials Central heating Central solar heating Chilled beam Chilled water Constant air volume (CAV) Coolant Dedicated outdoor air system (DOAS) Deep water source cooling Demand-controlled ventilation (DCV) Displacement ventilation District cooling District heating Electric heating Energy recovery ventilation (ERV) Firestop Forced-air Forced-air gas Free cooling Heat recovery ventilation (HRV) Hybrid heat Hydronics HVAC Ice storage air conditioning Kitchen ventilation Mixed-mode ventilation Microgeneration Natural ventilation Passive cooling Passive house Radiant heating and cooling system Radiant cooling Radiant heating Radon mitigation Refrigeration Renewable heat Room air distribution Solar air heat Solar combisystem Solar cooling Solar heating Thermal insulation Underfloor air distribution Underfloor heating Vapor barrier Vapor-compression refrigeration (VCRS) Variable air volume (VAV) Variable refrigerant flow (VRF) Ventilation
Bonney’s NATE certified technicians will troubleshoot and repair your furnace for safe and reliable operation. Our technicians use state of the art tools including video inspection cameras and exhaust gas analyzers to perform thorough, comprehensive diagnostics when equipment is broken. Furthermore, we arrive in a “warehouse on wheels” stocked with many parts to get your furnace repaired as quickly as possible.  For an unexpected heater repair Bonney offers financing to make your comfort affordable.
HVAC System Quality Installation Contractor Checklist -- This checklist identifies all of the steps the contractor has taken for the Energy Star Certification and identifies what work the contractor has done. If the system is later modified, this checklist can help identify what was done to proper Energy Star specifications and what was added later that may not meet the requirements.
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).[4][5][6]
R22 (also known as HCFC-22) has a global warming potential about 1,800 times higher than CO2.[61] It was phased out for use in new equipment by 2010, and is to be completely discontinued by 2020. Although these gasses can be recycled when air conditioning units are disposed of, uncontrolled dumping and leaking can release gas directly into the atmosphere.

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 electrical power required to move the air by a third.[26]
A dehumidifier is an air-conditioner-like device that controls the humidity of a room or building. It is often employed in basements which 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.
Humidity is becoming more of a concern to building operators and owners. High indoor humidity leads to mold and mildew growth inside the building. The are several methods of controlling indoor humidity. The simplest (and most expensive) method is to connect a humidistat to an electric heater. When the humidity inside the building rises above the humidistat set point, the heater is turned on. The additional heat causes the air conditioning system to run longer and remove more moisture.
Repair Clinic’s gas furnace troubleshooting guide will walk you through the steps necessary for diagnosing your furnace problem. Start with our list of symptoms. When you find the right one, we’ll show you the common causes. Enter your model number into the search field and you’ll know which part to buy. We can even show you how to install it. Where else can you find online furnace troubleshooting help like this?
In a chilled water system, liquid water is pumped throughout the building to “chilled water coils”. Since the liquid water needs to be at a cold temperature, a “cooling plant” is required. The plant is typically referred to as a chiller plant. Vapor compression equipment in the plant, similar to that described in “How does my AC work”, cool water to a cold temperature and pump the cold water to air-to-water heat exchangers where needed.
While there's nothing you can do to guarantee your air conditioner or furnace will never need repairs, there are ways to take better care of your system. Changing out the air filters every 3-6 months, making sure nothing is obstructing or interfering with the outside unit, and keeping all vents unblocked in well-used rooms will help keep your air conditioning and heating system operating efficiently.
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