A heat pump acts as a heat exchange system, moving warmth from the outside air into the home. New models employ technology that’s effective at warming the home when the outside temperature is as low as 37 degrees. During the summer, the unit dehumidifies and removes excess heat from the indoor air to cool it and push it back into the home.
The heat pump is effective by itself down to temperatures around 25 to 30 degrees Fahrenheit. At that point, either a gas furnace or an air handler with supplemental electric heat will kick in and help heat your home. Also, when temperatures outside drop very low the heat pump will automatically rely 100% on backup heat. This is to protect the compressor from the increasingly large temperature spread, which causes premature wear and tear.
If you’re used to a gas furnace, one noticeable difference from gas heat is that the air blowing through the vents usually comes out hotter with gas than with a heat pump. While the air may not initially feel as hot to the skin, the home still maintains your desired temperature by the heat pump operation.
A heat pump puts out much cooler air than a gas or oil furnace does, which many customers are used to. Furnaces tend to put out about 130 to 140-degree air. In contrast, a heat pump running by itself (with no supplemental backup heat) on a 35-degree day, might only put out 92-degree air. On a 20 degree day, it might drop to 85 degrees.
Simply put, this is lower than your body temperature, so it feels like cool air is blowing. But, it is still warmer than the indoor house temperature, so it is still putting heat into the house. Unlike a furnace that puts out a lot of heat for short periods of time, a heat pump will put out less heat for longer periods of time.
Heat pumps are tremendously efficient, even in cold weather. The efficiency does decline slightly as the temperature goes down, but even at very cold, single-digit temps, heat pumps are very efficient.