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Serving Southern Brazoria County

When to Worry about Heat Pump Ice

If you’re using a heat pump to keep warm this winter, you’re likely to see ice building up on the outside portion of the unit at some point. Under normal circumstances, this isn’t something you need to be concerned about. However, you should still keep an eye on it in case it starts to become a problem. In the wrong circumstances, heat pump ice can actually threaten the entire system.

Ice Formation

Heat pumps ice over because of the way they heat homes. During operation, the heat pump evaporates refrigerant to siphon thermal energy from the air around it. This causes the temperature of the air around the heat pump to drop, and condensation forms on the coil as it drops below the dew point. If the temperature of the air is dropped below freezing during this process, the condensate forms ice on the coil.

Heat pump manufacturers are well aware of this, and build defrost cycles into their units to deal with it. Every once in a while, the system will vent heat out of the outdoor unit in order to melt any ice that has built up. If this defrost cycle malfunctions, that’s when problems start to occur.


Ice that is allowed to build up unchecked on the heat pump coil will cut off the system’s access to the thermal energy it needs in the air. The output of the system will drop as more ice builds on the coil. The weight of the ice can also warp the coil, as well as travel down it to other parts of the system. This could easily cause a full system breakdown, if not treated. If your heat pump seems to be mostly covered in ice, it might be time to call for repairs.

Switzerland Air offers heat pump repair services throughout Lake Jackson, TX.

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