If you know even a little bit about the operation of the heat pump that keeps your household cool in summer and warm in winter, you’ll understand that the outside unit needs to absorb heat from the ambient air and carry it indoors in order for it to work in heating mode.
Should you notice that there is ice developing along the outdoor cabinet of the heat pump, it may worry you. Is this normal during the winter?
The answer is, confusingly, both yes and no. But we will quickly unconfuse you below:
Yes, it’s normal for the heat pump to have ice on it
When the temperature falls below 40°F and the relative humidity is high (around 70%), then it’s common for frost to begin to form along the heat pump’s outdoor coils. This is because as the coils absorb thermal energy from the air, they also absorb moisture that will form along the coils’ surface, where it will freeze because of the low temperatures. The heat pump has defrost controls to prevent this ice from accumulating and blocking the absorption of heat through the coils. The defrost control will periodically start a defrost cycle that switches the direction that heat moves through the coils, releasing heat and melting off the frost.
No, this needs to have repair technicians
If the frost forming on your heat pump doesn’t melt away after two hours or so, then there may be a problem that will require technicians to repair it. One possibility is that the defrost controls themselves have broken and aren’t activating the reversing valve that changes the direction of heat exchange in the pump. Another possibility is that the reversing valve itself had failed, so there’s no way to switch the heat pump’s mode (which will be bad news when spring arrives and you need the heat pump to start cooling you off). The worst-case scenario is that the unit is leaking refrigerant and losing its heat exchange abilities. This needs immediate remedy, so call on professionals as soon as possible.
Oasis Heating, A/C & Refrigeration offers repair services for heat pumps in Lorton, VA.