Instead of burning fossil fuels to create heat, heat pumps work by moving heat through a compressed refrigerant. Since it’s moving heat – not creating it – it’s 200-400% times more efficient than even the most efficient fossil fuel or electric resistance furnace or boiler.

There are three main types of heat pumps to know about: 

• Air source heat pumps: most common type, best for replacing a fossil fuel or electric resistance furnace
• Hydronic heat pumps: also known as “air-to-water” heat pumps, best for replacing radiators powered by a fossil fuel or electric resistance boiler
• Geothermal heat pumps: also known as “ground source” heat pumps, best if you want the highest efficiency heating and cooling system and have the land to do it

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Air source heat pumps

Air source heat pumps extract heat from outdoor air and transfer that air into your home in the winter. Even when it’s very cold outside – up to -22℉ – heat pumps are able to extract and transfer heat into your home. In the summer, they do the opposite – pulling heat out of your home and moving it outside like an air conditioner. 

Air source heat pumps can be installed in two ways: as a ducted system or as a mini-split, or ductless system.

Ducted systems

An outdoor compressor/condenser sits outside your home and an air handler sits inside, usually in an attic or basement. The air handler connects to standard ducting or high efficiency small ducting, and pushes warm and cool air through the home.

Mini-splits or ductless systems

Mini-splits, also referred to as “ductless” systems, connect to an outdoor compressor/condenser unit. Indoor unit(s) are installed in each room, and can often be controlled separately, giving you more precision in how you heat and cool your home. 

Mini-splits are a great option for homes that don’t have duct work already installed.

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Hydronic heat pumps

Hydronic heat pumps are technically a type of air source heat pump in that they rely on the same principles  – they pull heat out of the air to transfer it. 

Instead of pushing air, they use the energy to heat water. The warm water is then pushed throughout the home through radiators or in floor tubing, which warm up the rooms through radiant heat. They're sometimes referred to as air-to-water heat pumps.

Hydronic heat pumps can also be used to supply hot water, replacing both your HVAC system and your hot water heater in one.

To cool, the system works backwards to draw heat out of the home, send it over the coils of the heat pump, and sending the cool water back through the home.

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Geothermal heat pumps

Geothermal heat pumps use the earth as an exchange of heat through long loops of pipe buried underground. The temperature below the earth stays consistent – and like a cave, the underground temperature is warmer than the outside air during the winter and cooler than the outside air in the summer.

Depending on the type of installation, geothermal heat pumps require trenches to be dug at least 4-6 feet deep. Inside the home, the warm and cool air is circulated through ducts or as radiant heat.

Geothermal heat pumps are more expensive than air source and hydronic heat pumps. However, you can deduct 30% of a geothermal installation from your taxes, while the other types of heat pump incentives cap out at $2,000.

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