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Heat Pump Terminology

This page presents terminology relating to heat pump technology.

  1. Evaporator:
    • In a heat pump water heater, the evaporator is the component where the refrigerant absorbs heat from its surroundings, typically the ambient air or water.
  2. Compressor:
    • The compressor is responsible for increasing the pressure and temperature of the refrigerant vapor, facilitating its movement through the system.
  3. Condenser:
    • The condenser is where the high-pressure, high-temperature refrigerant releases heat to the water in the storage tank, causing it to condense back into a liquid state.
  4. Expansion Valve:
    • This component regulates the flow of the refrigerant and reduces its pressure before it enters the evaporator, allowing it to absorb heat efficiently.
  5. Heat Exchanger:
    • A heat exchanger transfers heat between the refrigerant and the water in the storage tank, enabling the water to be heated by the heat extracted from the surroundings.
  6. Microchannel:
    • Microchannel refers to a type of heat exchanger design that uses small channels to enhance heat transfer between the refrigerant and the water.
  7. Refrigerant:
    • Refrigerant is a substance used in the heat pump cycle to absorb and release heat as it undergoes changes in state (from vapor to liquid and vice versa).
  8. Pump:
    • In the context of a heat pump water heater, a pump may be used to circulate water through the heat exchanger or storage tank.
  9. COP (Coefficient of Performance):
    • COP is a measure of the efficiency of a heat pump water heater, calculated as the ratio of the heat output to the electrical power input.
  10. Thermal Capacity:
    • The amount of heat energy that a material or system can store or absorb.
  11. Power:
    • In the context of a heat pump water heater, power refers to the electrical power consumed by the system to operate the compressor, pump, and other components.
  12. Storage Tank:
    • The storage tank holds the water that is heated by the heat pump system, providing a reservoir of hot water for domestic use.
  13. Air-Source:
    • Refers to heat pump systems that extract heat from the ambient air to heat the water in the system.
  14. Water-Source:
    • Heat pump systems that extract heat from a water source, such as a well or a body of water, to heat the water in the system.
  15. Backup Heating Element:
    • Some heat pump water heaters are equipped with an electric heating element as a backup for periods of high demand or low ambient temperatures when the heat pump alone may not be sufficient.
  16. Heat Pump Water Heater Modes:
    • Some systems have different operating modes, such as “heat pump only,” “hybrid” (combining heat pump and backup heating element), or “electric resistance” (using only the backup heating element).
  17. Tank Insulation:
    • The insulation around the storage tank is crucial for minimizing heat loss and improving overall energy efficiency.
  18. Anode Rod:
    • An anode rod is often present in the storage tank to help prevent corrosion by attracting corrosive elements and sacrificing itself.
  19. Temperature and Pressure Relief Valve (TPR Valve):
    • A safety feature that releases water if the temperature or pressure in the tank exceeds safe levels.
  20. Ductwork (for air-source heat pump water heaters):
    • In installations where the heat pump extracts heat from the air, ductwork may be necessary to circulate air to and from the heat pump unit.
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