A heat pump is equipped with a “defrost cycle” that allows the unit to melt accumulated ice during operation. This cycle is activated only in heating mode.
A heat pump must make a defrost mode every hour or on demand depending on the model.
A defrost cycle allows the unit to defrost ice that has formed around the compressor and on the outdoor condenser. Defrosting can be short-lived and can last up to 10 minutes.
You know the unit goes into defrost mode when:
1. The outdoor fan stops working;
2. The compressor begins to rumble;
3. Depending on the outdoor relative humidity, smoke may be visible around the unit;
4. There is a water flow at the bottom of the unit;
5. The furnace takes over if there is a heating demand;
At the end of the defrost cycle:
1. The compressor emits a rumble;
2. The ventilator is restarting;
3. Smoke can be released again;
4. And finally the device is ready for a next heating request.
All of its steps are automatically done in parallel with the thermostat and the heating system.