To explain a Heat Pump it’s important that you first read the section on Air Conditioners and How an Air Conditioner Works.

From the outside a heat pump looks just like an air conditioner – and works just like an air conditioner in the “cooling” mode. When it needs to produce heat, it reverses its cycle. Yes, even if it is 0 degrees Fahrenheit outside, the outdoor unit “absorbs” heat from the outside air that passes through the outdoor coil. By pressurizing the refrigerant with a compressor, it actually raises the temperature of the refrigerant to the point it can give off heat as it passes through the indoor coil.

Obviously a heat pump works better the warmer it is outside, so in most cases it needs a “back up” heat source, typically electric – but sometimes gas or oil. You might wonder why it makes sense to have a heat pump when you need a back up source. Heat pumps have the ability to produce as much as 3 times more heat for the money than an electric furnace, and they are becoming more efficient as technology improves. Heat pumps come in window units, PTACs, split systems, package units and ductless split systems.

One of the easiest ways to identify a heat pump is to look at your thermostat. If you have a “back up” or “secondary” heat switch, it’s a good chance that your system is a heat pump.

Geothermal Heat Pumps

A Geothermal Heat Pump uses the same principle as a standard heat pump or air conditioner, except it does not have an outdoor unit with a fan. The most common type of geothermal unit uses water that passes over a coil. The water either adds or removes heat from the coil depending on if it is heating or cooling. The reason geothermal units are some of the most efficient systems available are due to the relatively constant temperature of water, compared to the extremes of a heat pump that uses the outside temperature of the air. Geothermal units are among the most expensive systems to install, due to the cost of the burying a water coil underground.

A good way to identify a geothermal system is to first identify it as a heat pump, but without the outdoor unit.

Air Handlers

The Air Handler is the indoor portion of an air conditioning system or heat pump when a standard furnace is not being used in the system.