Hansberger Refrigeration Blog: Your AC Repair Resource

Your Heat Pump and Its 3 Cooling, Heating and Defrost Cycles

Air-source heat pumps have three cycles that allow them to operate as both cooling and heating solutions for your Southwest Arizona home. Starting with the heat pump cooling cycle, here is an overview of these three cycles.

Your Heat Pump and Its 3 Cooling, Heating and Defrost CyclesCooling Cycle

Living in the desert Southwest as we do, the heat pump cooling cycle is going to be where your heat pump spends most of its operational time. While operating in this mode, your heat pump uses the heat-exchange properties of refrigerant to transfer heat from the inside of your home to the outside air, producing the cooling effect.

The steps in this cycle are:

  • Liquid refrigerant inside the heat pump is expanded, creating a liquid-vapor.

  • The liquid-vapor then moves through the indoor evaporator coil, absorbing heat from the air and further expanding in to a vapor.

  • The vapor next moves in to the compressor in the outside unit, which concentrates the heat that the vapor has gained by reducing its volume.

  • The heated refrigerant vapor moves through the outdoor condensing coil, transferring heat to the outside air.

  • The cycle then repeats, the vapor having become a liquid again and moving inside.

Heating Cycle

The heating cycle is essentially the reverse of the heat pump cooling cycle described above. It uses refrigerant to transfer heat from the air outside into your home.

A quick overview of the steps in reverse looks like:

  • Liquid refrigerant is expanded.

  • It moves through the outdoor coil first this time, absorbing heat from outside.

  • It is compressed, heating it up.

  • It next moves through the indoor coil, transferring heat to the inside air.

  • Again, the cycle repeats.

Defrost Cycle

The defrost cycle exists to ensure that your heat pump can operate in near or below freezing temperatures. If frost builds up on the outdoor coil, the heating performance of your heat pump can suffer. The defrost cycle works by reversing the cycle, just as it would for cooling. Hot refrigerant gas is directed outside to defrost the outdoor coil. Once defrosted, the heat pump can resume the heating cycle. This, of course, isn’t a frequent operation in our warm climate.

At Hansberger Refrigeration and Electric Company, we have been serving the Yuma area since 1952. For any advice regarding heat pumps or other HVAC solutions, you can always contact us.




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Our goal is to help educate our customers in Yuma, Arizona about energy and home comfort issues (specific to HVAC systems).  For more information about heat pumps and other HVAC topics, download our free Home Comfort Resource guide.

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