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How does an air source heat pump work?

For those that consider the reduction of their CO2 emissions as important as lowering their heating bills, air-source heat pumps could represent the perfect solution.

What is an air source heat pump?

Air source heat pumps absorb heat from the air outside and use it to heat the inside of your home, as well as provide you with low-cost hot water.

These pumps are usually the air-to-water kind and require electricity to run. However, the heat they can extract from outside is often greater than the energy input required, making them an efficient way of heating up your home.

They work by absorbing air at low temperatures as a liquid. This then passes through a compressor and increases in temperature before transferring into the central heating system.

There’s a choice of two air-source heat pumps: air to water and air-to-air systems. Understanding both will tell you what kind of heat distribution system you will require.

What’s the difference between an air-to-water heat pump and an air-to-air heat pump?

Air to water heat pumps are the most common type of air-source heat pump and can provide both heating and hot water. They transfer heat from the air outside your home into water, which is distributed via your central heating system. Efficiencies are the result of the system running at temperatures significantly lower than a standard boiler.

This makes them a great choice for underfloor heating or larger radiators, which emit heat at lower temperatures over longer periods. Air-to-air pumps, on the other hand, require an added warm air circulation system to move the warm air around your home. They are also limited in that they don’t provide you with hot water.

Another negative aspect of air-to-air pumps is that they don’t qualify under the Government’s Renewable Heat Incentive, which can provide payments to households for providing their own heating supply.

What are the benefits of air source heat pumps?

There are a host of benefits, with the biggest being the money you could save on your heating bills.

Based on a four-bedroom detached house, the cost of an air source pump is usually between £9,000 to £11,000. Despite the outlay, it could pay for itself within seven years thanks to energy savings worth £360 a year and the Government’s Domestic Renewable Heat Incentive (RHI), which could pay out around £1,200 per year.

Other benefits include low maintenance and the fact that, unlike other heating alternatives such as biomass boilers, no fuel deliveries are required.

Air source heat pumps can also significantly reduce the amount of CO2 that your home produces. While the exact reduction will depend on the type of system that you’re replacing, an air source heat pump could save more than two tonnes of carbon per year. This is 20% less than gas boilers and a massive 70% less than electric systems.

Are there any grants for air source heat pumps?

There are a number of air source heat pump grants available that can cover a substantial part of the cost of the fitting. The main ones are the Energy Company Obligation (ECO) grant, and the Green Homes Grant voucher scheme.

What are ECO Grants?

The Government’s Energy Company Obligation (ECO) is a government-backed energy efficiency scheme that obligates the UK’s big energy companies to help customers on certain benefits afford energy-saving home improvements. Not only does this scheme provide funding for a free boiler, but it also covers a range of other energy-saving measures. This includes air source heat pumps.


What is the Green Homes Grant Voucher Scheme?

The Green Homes Grant voucher scheme (GHGVS) provides vouchers for energy efficiency measures, including funding for air source heat pumps. It is split between those on low incomes and certain benefits, who can apply for vouchers that cover the total cost up to £10,000, and a general scheme that is open to everybody and provides grants that cover two-thirds of the cost, up to £5,000.