What Is a Heat Pump and How Is It Different?

How a heat pump works

A heat pump is a central air conditioning and heating system that extracts heat from the air for cost effective comfort in all but the most severe winter climates. Unlike a furnace, it does not burn fuel to make heat. It simply uses electricity to move heat from one place to another. In cooling mode, the system captures heat from inside your home and transfers it outside. In heating mode, it reverse cycles, capturing heat from outside and moving it indoors. Transferring existing heat is far less expensive than generating heat, which is why a heat pump is more efficient than standard electric heat.

How it differs from a furnace

A furnace makes heat by burning gas, oil, or propane, or by running electric resistance elements. A heat pump makes no heat of its own. It relocates heat that already exists in the outdoor air. Because one unit handles both cooling in summer and heating in winter, a heat pump replaces the need for a separate air conditioner and furnace in many homes.

Performance in cold weather

There is usable heat in outdoor air down to about 0 degrees Fahrenheit. It feels cold to us because our body temperature is 98.6 degrees. A heat pump's heating capacity is rated at 47 degrees ambient outdoor temperature. As the outdoor temperature drops, capacity drops in a linear fashion relative to that temperature. Most heat pumps produce about half of their rated capacity near 12 degrees ambient.

Backup electric heat

An electric heating element provides supplemental heat to assist the heat pump as its capacity declines in colder weather. The system monitors both the outdoor temperature and the indoor supply air temperature, then energizes the backup heat automatically as needed. This keeps your home comfortable even when outdoor temperatures fall well below the rating point.