A heat pump is a device that takes low-temperature heat from a source such as the outdoor air and increases that heat in an energy-efficient way. This heat can then be transferred, for example, to water that circulates around radiators or an underfloor heating system.
A heat pump uses electricity to drive a compressor that raises the temperature of that source heat energy very efficiently – much like your refrigerator but in reverse. The exact efficiencies depend on size of the system and the outdoor / indoor temperature difference. But, on average, 1 kilowatt of electricity can produce approximately 3 kilowatts of heat. Heat pumps can also transfer heat from sources such as the ground (known as a ground-source heat pump) or water in nearby lakes or rivers (a water-source heat pump).
The most common heat pump found in UK homes today is the air-to-water type. This has an outdoor unit (about 1m wide by 1m tall and 350mm deep) that collects heat from the outdoor air and raises the temperature to heat water for your radiators or underfloor heating. The heat pump can also provide hot water to a cylinder in your home for use in showers and hot taps.
Because they’re electrically powered, heat pumps can make use of the UK’s wind-generated electricity, making them a low-carbon heating system. It is also possible to use electricity from solar panels (photovoltaics or ‘PVs’) which could be mounted on the roof of the house. Unlike a fossil fuel boiler, heat pumps produce zero carbon emissions at your home.