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ACI Northwest Blog

Understanding the Heat Pump Defrost Cycle: A Guide from Greenacres

If your Greenacres home has a heat pump, you’ll want to understand the defrost cycle to help you maintain your heat pump and troubleshoot repairs. While this is a basic guide, you should call a qualified HVAC technician if you experience major issues with your heat pump.

During the winter when a heat pump is heating your home, the cooler outdoor air that’s pumped in and heated may have excess moisture. The outdoor coil evaporates this moisture, but under certain weather conditions, frost can accumulate on the coil and decrease the overall efficiency of the heat pump.  To help reduce the potential for damage from the frost, heat pumps are manufactured with a defrost cycle to melt the frost from the outdoor coil. The defrost cycle occurs often during heavy frost conditions, so check weather reports if your defrost cycle seems to be running often.

At the beginning of the defrost cycle, the heat pump switches to the cooling mode and temporarily warms up the outdoor coil until it reaches somewhere around 60° F to melt the frost from the coil. To increase the temperature of the coil, the outdoor fan is prevented from turning on until the outdoor coil reaches the desired temperature. Weather conditions and the timing device both affect the amount of time it takes for the heat pump to move through the entire defrost cycle.

In older homes, electric heating pumps are sometimes installed to prevent cool air from being distributed throughout the home. This element will turn on with the defrost cycle and shut down the blower fan inside the house. If you have an older heat pump, you may want to consider upgrading to a more efficient model.

Call ACI NW any time if you have questions about the defrost cycle for the heat pump in your Greenacres home.

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