Reversing valve
Encyclopedia
A reversing valve a type of valve and is a component in a heat pump
Heat pump
A heat pump is a machine or device that effectively "moves" thermal energy from one location called the "source," which is at a lower temperature, to another location called the "sink" or "heat sink", which is at a higher temperature. An air conditioner is a particular type of heat pump, but the...

, that changes the direction of refrigerant
Refrigerant
A refrigerant is a substance used in a heat cycle usually including, for enhanced efficiency, a reversible phase change from a liquid to a gas. Traditionally, fluorocarbons, especially chlorofluorocarbons, were used as refrigerants, but they are being phased out because of their ozone depletion...

 flow. By reversing the flow of refrigerant, the heat pump refrigeration cycle
Heat pump and refrigeration cycle
Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pumps and refrigerators. A heat pump is a machine or device that moves heat from one location at a lower temperature to another location at a higher temperature using mechanical work or a...

 is changed from cooling
Cooling
Cooling is the transfer of thermal energy via thermal radiation, heat conduction or convection. It may also refer to:-Techniques:* Air conditioning* Air cooling* Computer cooling* Cryogenics* Conduction * Infrared solar cells* Laser cooling...

 to heating or vice versa. This allows a residence or facility to be heated and cooled by a single piece of equipment, by the same means, and with the same hardware.

Operation

The reversing valve has two states, relaxed and energized. The energized state is typically achieved by applying 24 volts of alternating current
Alternating current
In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....

, which is commonly used in HVAC
HVAC
HVAC refers to technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer...


. The heat pump can be designed by the manufacturer to produce cooling or heating with the reversing valve in the relaxed state. When the reversing valve is energized, it will produce the opposite conditioning. In other words, a reversing valve installed in such a way as to produce cooling when relaxed will produce heating when energized. Likewise, a reversing valve installed to produce heating when relaxed will produce cooling when energized.

Control

Depending on the construction and use of the heat pump, the reversing valve may be driven by the heat pump through the use of a control board
Microcontroller
A microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM...

, or it may be driven directly by a thermostat (typically from the "O" terminal).

Replacement

Reversing valves are built into the heat pump by the manufacturer, and must be replaced by an HVAC technician
Technician
A technician is a worker in a field of technology who is proficient in the relevant skills and techniques, with a relatively practical understanding of the theoretical principles. Experienced technicians in a specific tool domain typically have intermediate understanding of theory and expert...

 if they fail.

See also

Reversing Valve Uses
  • Heat pump
    Heat pump
    A heat pump is a machine or device that effectively "moves" thermal energy from one location called the "source," which is at a lower temperature, to another location called the "sink" or "heat sink", which is at a higher temperature. An air conditioner is a particular type of heat pump, but the...

  • Geothermal heat pump


HVAC Information
  • HVAC
    HVAC
    HVAC refers to technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer...

  • Refrigeration cycle


Other HVAC Components
  • Thermostat
  • Freon compressor
  • Heat exchanger
    Heat exchanger
    A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall, so that they never mix, or they may be in direct contact...

  • Thermal expansion valve
    Thermal expansion valve
    A thermal expansion valve is a component in refrigeration and air conditioning systems that controls the amount of refrigerant flow into the evaporator thereby controlling the superheating at the outlet of the evaporator...

  • Freeze stat
    Freeze stat
    - Freeze Stat :A freeze stat is a temperature sensing device for HVAC that monitors a heat exchanger to prevent its coils from freezing. Freeze stats can be used on both freon-to-air, and freon-to-liquid type heat exchangers and serve different purposes with similar goals for each.- Air coil...

  • Freon
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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