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2. Heating, ventilation, and air conditioning - Wikipedia

   en.wikipedia.org/wiki/Heating,_ventilation,_and...

   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 ...

3. Thermal expansion valve - Wikipedia

   en.wikipedia.org/wiki/Thermal_expansion_valve

   A thermal expansion valve is a key element to a heat pump; this is the cycle that makes air conditioning, or air cooling, possible. A basic refrigeration cycle consists of four major elements: a compressor, a condenser, a metering device and an evaporator. As a refrigerant passes through a circuit containing these four elements, air ...

4. Thermostatic radiator valve - Wikipedia

   en.wikipedia.org/wiki/Thermostatic_radiator_valve

   A thermostatic radiator valve on position 2 (15–17 °C) Installed thermostatic radiator valve with the adjustment wheel removed A thermostatic radiator valve (TRV) is a self-regulating valve fitted to hot water heating system radiator, to control the temperature of a room by changing the flow of hot water to the radiator.

5. Heat pump - Wikipedia

   en.wikipedia.org/wiki/Heat_pump

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

6. Air conditioning - Wikipedia

   en.wikipedia.org/wiki/Air_conditioning

   The efficiency of air conditioners is often rated by the seasonal energy efficiency ratio (SEER), which is defined by the Air Conditioning, Heating and Refrigeration Institute in its 2008 standard AHRI 210/240, Performance Rating of Unitary Air-Conditioning and Air-Source Heat Pump Equipment. [61]

7. Thermostat - Wikipedia

   en.wikipedia.org/wiki/Thermostat

   The reversing valve, controlled by the thermostat, causes the change-over from heat to cool. Residential heat pump thermostats generally have an "O" terminal to energize the reversing valve in cooling. Some residential and many commercial heat pump thermostats use a "B" terminal to energize the reversing valve in heating.