Air to water heat pumps extracts their heat energy from the outside air in order to heat your home or business. An air to water heat pump has an external heat exchanger unit that is like a car radiator but instead of expelling heat to the air it takes heat from the air. The air is pulled through the heat exchanger by a fan whenever the heat pump is on. The air to water heat pump heat exchanger has a refrigerant running through it which is able to absorb heat at a low temperature. Air to water heat pumps can heat your house or building even when it is as low as -15 degrees outside.
This refrigerant is then compressed or ‘pumped up’ to a higher temperature by the compressor just like in your fridge. This higher temperature heat is then passed to the water that circulates around through your radiators or under floor heating to heat your house or to your hot water tank to heat your shower and sink water. The temperature that the air to water heat pump gets from the air may only be at a low temperature but that heat can be pumped up to heat the water to 55 or 60 degrees.
From two thirds to three-quarters of the heat energy the air to water heat pump supplies to your home comes free from the air, you are only paying for a quarter of the heat energy you put into your house or building.