Air source heat pumps absorb heat from the outside to heat buildings. There are two types of air-source heating systems. Air-to-air systems provide warm air, which is circulated to heat the building. The other type, air-to-water, heat water to provide heating to a building through radiators or an underfloor system. BenefitsThe benefits of air source heat pumps are similar to ground-source heat systems. Firstly, neither type of system requires the use or storage of external fuel. The systems instead run on electricity, which eliminates the need for a gas connection or storage of oil/solid fuel. Air source heat pumps present an advantage over ground source heat pumps because they require less space to install. Instead of requiring the installation of buried underground coils, air source systems can be fitted using much less space and are therefore, more suited for an urban home. How it worksIn the same way that a fridge uses refrigerant to extract heat from the inside, keeping your food cool, and air source heat pump extracts heat from the outside air, and uses it to heat your home and hot water. An air-source heat pump has three main parts: - The evaporator coil absorbs heat from the outside air;
- The compressor pumps the refridgerant through the heat pump and compresses the gaseous refridgerant to the temperature needed for the heat distribution circuit;
- The heat exchanger transfers the heat from the refridgerant to air or water.
In an air-to-water system, the heat produced is used to heat water, which can be used to pre-heat water in a storage tank or circulate through underfloor heating or radiators. Heat pumps produce hot water that is a lower temperature (typically 35-45C) than standard boiler systems, which makes underfloor heating the most effective option. In an air-to-air system, this heat is used to produce warm air, which is circulated by fans to heat a building. The efficiency of air source systems is measured by a coefficient of performance (CoP). CoPs for air source systems are comparable with ground-source heat pumps, and generally range between 3 and 4. This means that for every unit of electricity used to power the pump, 3-4 units of heat are produced, making it an efficient way of heating a building. It is even possible for air source heat pumps to extract useful heat from air at temperatures as low as minus 15 oC.
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