Why does our heat pump not work properly if it is below freezing outside?
Heat pumps are only effective to about 35 degrees. Anything lower than that, you have to use your emergency heat. The two reasons for this are that when the outdoor air temp. gets too cold, the unit cannot extract as much heat from the outdoor air to keep up with heating demand. Second, condensation forms on the outdoor unit when it is running. In temps above 32 deg (freezing point of water), the condensation simply drains away from the unit. Below 32 deg the condensation freezes to the coil and blocks air flow. When this happens, the unit must go into defrost mode to clear the ice. During this time the heat pump is not heating your house. It is heating the outdoor unit to clear the ice.
