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How Does a Heat Pump Work?

By December 11, 2019August 26th, 2020No Comments

How Does a Heat Pump Work?An air-source heat pump uses advanced technology and the refrigeration cycle to heat and cool your home. This allows a heat pump to provide year-round indoor comfort – no matter what the season is.
Simply put, a heat pump is a device that uses a small amount of energy to move heat from one location to another. Not too difficult, right? Heat pumps are typically used to pull heat out of the air or ground to heat a home or office building, but they can be reversed to cool a building. In a way, if you know how an air conditioner works, then you already know a lot about how a heat pump works. This is because heat pumps and air conditioners operate in a very similar way.

Heat Pump in Air Conditioning Mode

When properly installed and functioning, a heat pump can help maintain cool, comfortable temperatures while reducing humidity levels inside your home.

  1. Warm air from the inside of your house is pulled into ductwork by a motorized fan.
  2. A compressor circulates refrigerant between the indoor evaporator and outdoor condensing units.
  3. The warm air indoor air then travels to the air handler while refrigerant is pumped from the exterior condenser coil to the interior evaporator coil. The refrigerant absorbs the heat as it passes over the indoor air.
  4. This cooled and dehumidified air is then pushed through connecting indoor ducts to air vents throughout the home, lowering the interior temperature.
  5. The refrigeration cycle continues again, providing a consistent method to keep you cool.

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Heat Pump for Heating

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Heat Pump for Heating

Heat Mode

Heat pumps have been used for many years in locations that typically experience milder winters. However, air-source heat pump technology has advanced, enabling these systems to be used in areas with extended periods of subfreezing temperatures.

  • A heat pump can switch from air condition mode to heat mode by reversing the refrigeration cycle, making the outside coil function as the evaporator and the indoor coil as the condenser.
  • The refrigerant flows through a closed system of refrigeration lines between the outdoor and the indoor unit.
  • Although outdoor temperatures are cold, enough heat energy is absorbed from the outside air by the condenser coil and release inside by the evaporator coil.
  • Air from the inside of your house is pulled into duct-work by a motorized fan.
  • The refrigerant is pumped from the interior coil to the exterior coil, where it absorbs the heat from the air.
  • This warmed air is then pushed through connecting ducts to air vents throughout the home, increasing the interior temperature.
  • The refrigeration cycle continues again, providing a consistent method to keep you warm.

Parts of a Heat Pump

To get a better idea of how your air is heated or cooled, it helps to know a little bit about the parts that make up the heat pump system. A typical air-source heat pump system is a split or two-part system that uses electricity as its power source. The system contains an outdoor unit that looks similar to an air conditioner and an indoor air handler. The heat pump works in conjunction with the air handler to distribute the warm or cool air to interior spaces. In addition to the electrical components and a fan, a heat pump system includes:

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  • Compressor: Moves the refrigerant through the system. Some heat pumps contain a scroll compressor. When compared to a piston compressor, scroll compressors are quieter, have a longer lifespan, and provide 10° to 15°F warmer air when in the heating mode.
  • Control board: Controls whether the heat pump system should be in cooling, heating or defrost mode.
  • Coils: The condenser and evaporating coil heat or cool the air depending on the directional flow of refrigerant.
  • Refrigerant: The substance in the refrigeration lines that circulates through the indoor and outdoor unit.
  • Reversing valves: Change the flow of refrigerant, which determines if your interior space is cooled or heated.
  • Thermostatic expansion valves: Regulate the flow of refrigerant just like a faucet valve regulates the flow of water.
  • The accumulator: A reservoir that adjusts the refrigerant charge depending on seasonal needs.
  • Refrigeration lines and pipes: Connect the inside and outside equipment.
  • Heat strips: An electric heat element is used for auxiliary heat. This added component is used to add additional heat on cold days or to recover from lower set back temperatures rapidly.
  • Ducts: Serve as air tunnels to the various spaces inside your home.
  • Thermostat or control system: Sets your desired temperature.


One of the biggest advantages of a heat pump over a standard heating ventilating and air conditioning (HVAC) unit is that there’s no need to install separate systems to heat and cool your home. Heat pumps also work extremely efficiently, because they simply transfer heat, rather than burn fuel to create it. This makes them a little more green than a gas-burning furnace. And they don’t just heat and cool buildings. If you’ve ever enjoyed a hot tub or heated swimming pool, then you probably have a heat pump to thank. They work best in moderate climates, so if you don’t experience extreme heat and cold in your neck of the woods, then using an air source heat pump instead of a furnace and air conditioner could help you save a little money each month.

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