A heat pump isn’t like a furnace. Instead of producing its own heat, it pulls environmental heat energy out of the outside air and transfers it indoors. While this allows it to reach three to four times the efficiency of a furnace, it also makes the air near the heat pump cooler as heat is extracted, which can lead to frost buildup. So what do you do when a heat pump freezes over, and what exactly is happening?
Heat Pump Defrost Cycle
As the heat pump causes the temperature near it to drop, it’s not uncommon for a fine coating of frost to collect on the coils. However, when this occurs, it’s more difficult for the coils to extract heat through the frost layer.
Heat pumps periodically go into a defrost mode, running in reverse for a short period of time in order to melt the frost. (If you have a back-up heat source, it may engage at this time.) But when a heat pump freezes over, it may develop much more than a layer of frost. The entire outdoor unit may become encased in a crust of ice.
What to Do If the Heat Pump Freezes Over
If the heat pump freezes over, there could be several causes. Some can be fixed relatively easily, while others require a call to your local HVAC experts.
- Periods of freezing rain can ice over the unit, or an overhanging gutter or tree can drip water onto the unit.
- The coil may be blocked by leaves or overgrowth or be sunk too far into the ground to allow melting frost to run off.
- The timer or sensor that controls the defrost cycle may be faulty.
- The heat pump’s reversing vale may be stuck or broken.
- The system may be low on refrigerant.
If your heat pump freezes over this winter, look to see if there are any obvious obstructions. If there aren’t, contact the heating and cooling pros at Victory • Heating • Air Conditioning • Plumbing! We’re happy to help our neighbors in Bellingham and surrounding communities.
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