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  2. Variable refrigerant flow - Wikipedia

    en.wikipedia.org/wiki/Variable_refrigerant_flow

    Variable refrigerant flow (VRF), also known as variable refrigerant volume (VRV), is an HVAC technology invented by Daikin Industries, Ltd. in 1982. [1] Similar to ductless mini-split systems, VRFs use refrigerant as the primary cooling and heating medium, and are usually less complex than conventional chiller -based systems.

  3. Variable air volume - Wikipedia

    en.wikipedia.org/wiki/Variable_air_volume

    The difference between a CAV and VAV box is that a VAV box can be programmed to modulate between different flowrate setpoints depending on the conditions of the space. The VAV box is programmed to operate between a minimum and maximum airflow setpoint and can modulate the flow of air depending on occupancy, temperature, or other control ...

  4. Forced-air - Wikipedia

    en.wikipedia.org/wiki/Forced-air

    An alternative to a constant air volume system is a variable air volume (VAV) system. [6] Variable air volume systems are generally more complex than their CAV counterparts because they must utilize temperature control and control the actual volume of air blown into each room. [7]

  5. Heating, ventilation, and air conditioning - Wikipedia

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

    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 ...

  6. Dedicated outdoor air system - Wikipedia

    en.wikipedia.org/wiki/Dedicated_outdoor_air_system

    DOAS air handling unit with heat recovery wheel and passive dehumidification. A dedicated outdoor air system (DOAS) is a type of heating, ventilation and air-conditioning system that consists of two parallel systems: a dedicated system for delivering outdoor air ventilation that handles both the latent and sensible loads of conditioning the ventilation air, and a parallel system to handle the ...

  7. Heat recovery ventilation - Wikipedia

    en.wikipedia.org/wiki/Heat_recovery_ventilation

    Diagramatic operation of a thermal wheel Ljungström Air Preheater by Swedish engineer Fredrik Ljungström (1875–1964). A thermal wheel, also known as a rotary heat exchanger, or rotary air-to-air enthalpy wheel, energy recovery wheel, or heat recovery wheel, is a type of energy recovery heat exchanger positioned within the supply and exhaust air streams of air-handling units or rooftop ...

  8. Refrigerant - Wikipedia

    en.wikipedia.org/wiki/Refrigerant

    A DuPont R-134a refrigerant. A refrigerant is a working fluid used in cooling, heating or reverse cooling and heating of air conditioning systems and heat pumps where they undergo a repeated phase transition from a liquid to a gas and back again.

  9. Glossary of HVAC terms - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_HVAC_terms

    The heat is rejected to deep lake regions to cool homes and offices, reducing the energy costs. ΔT (Also delta T) a reference to a temperature difference. It is used to describe the difference in temperature of a heating or cooling medium as it enters and as it leaves a system. dehumidifier