Heat pumps FAQ

Heat pump system


Most frequent questions and answers

A heat pump uses electricity and refrigerant to move heat from one area to another. In winter, ambient heat is drawn from the outside air or from underground, concentrated by means of a compressor, than blown into the space to be heated. In summer, the system is reversed internally as called for by your thermostat to remove heat from the indoor space, thereby cooling that space, and moving that heat outdoors or underground.

Think of a window-style box air conditioner. In summer it’s blowing cold air inside and hot air outside. Now imagine turning it around in the winter. A heat pump system does that without the heavy lifting.

If you have a refrigerator, you’ve been using heat pump technology all along. Heat pump technology has been around for decades and proven reliable and safe.

Since the electricity used by heat pumps does not directly create heat, as is the case with electric resistance heat and fossil fuel systems, but instead is used only to operate the fans, compressors and pumps, they are super efficient. With the original source of the heat being natural solar or geothermal, heat pump systems can claim efficiency rates of approximately 300%.

An air-sourced heat pump system starts with an outside condenser unit (looks like an outside A/C fan unit) that in the winter extracts ambient heat from outside and transfers it via refrigerant line to the inside wall or ceiling unit (called a ductless “mini-split” system), where it can be blown into the space to be heated. The refrigerant line can alternatively be connected to a central unit similar to a typical furnace which then uses ducts to blow the heated air throughout a several room area. For a ground-source system, underground liquid-filled loops collect heat which is then transferred to the central unit. In the summer, the directions of flow switch in both air and ground-source systems to provide the needed cooling.

The newest “Cold Climate” heat pumps work well until about -13ºF, below which they become less efficient. Most heat pump systems have a built-in electric resistance backup to make up for loss of efficiency at temps below that. And while it is possible to use methane (“natural”) gas for the backup heat, other options are available to enable homeowners to maintain a fossil-free home even in cold climates.

Burning gas to heat your home releases toxic emissions such as nitrogen dioxide, carbon dioxide, and fine particulate matter (PM2.5). Multiple studies have associated these emissions with diseases and illnesses including asthma, COPD, pulmonary fibrosis, cancer, Alzheimers, mental illness, childhood IQ and development, and premature death. The carbon monoxide produced is a byproduct of gas combustion must be properly vented to prevent backdrafting and possible CO poisoning. The numerous gas pipes, lines, valves, fittings, etc. in your home can all leak presenting the possibility of fires and explosions in addition to the health concerns. Heat pumps run on electricity only, without any home combustion, burning fuels, need for venting of toxic gases, or gas infrastructure.