Heat pumps explained: how do they work and are they right for your home?

We asked heating expert Kevin Ellis to explain how heat pumps work and the benefits and costs of installing one in your home

heat pump
Published: August 25, 2021 at 8:12 am
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With the Government committed to reaching net zero carbon emissions by 2050, now is the time to rethink our dependence on fossil fuels in the home. For most of us, central heating is the leading consumer of energy, particularly in the depths of winter. However, did you know it's possible to replace your boiler with an air-source heat pump to heat your home naturally?

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We talked to Kevin Ellis, from heating and renewables experts Grant UK, to answer all our questions about how heat pumps work, and how to tell if they are right for your home.

What is an air-source heat pump?

Air-source heat pumps extract low temperature heat from the air and convert it into a higher temperature heat you can use to heat your home.

There are two types of air source heat pumps: ‘air to air’ systems, which use fans to directly circulate the warm air produced to heat your home, but not your water; and ‘air to water’ systems, which capture heat energy from the air and transfer it into ‘wet’ heating systems such as radiators or underfloor heating. Air to water is the more popular type of air source heat pump.

Can I replace my old boiler with a heat pump?

In most cases, yes, a heat pump can provide all the heating and hot water you would need. Heat pumps can be an especially intelligent choice for those households that aren’t connected to mains gas

However, it is important that your property is well insulated and your heat pump system correctly designed. Air source heat pumps operate at lower system temperatures compared with traditional gas or oil-fired boilers, so to ensure the heat pump can effectively meet a home’s heating requirements, heat loss from the property must be minimised.

Most homes will already have high levels of insulation, but for older properties measures which can reduce heat loss including double glazing and wall and roof insulation.

It is also very important that the radiators are correctly sized (larger radiators are usually needed) so that the desired room temperatures can be met by the heat pump’s lower system temperature. This is one of the reasons why underfloor heating works so well with heat pumps, providing a large surface area to evenly distribute warmth into a room.

Basically, provided the system has been correctly designed and specified, a heat pump can suit new-builds, older properties, flats and many other types of home.

How much does it cost to install a heat pump?

The initial installation cost is significant, starting from £8,000 including upgrading radiators and installing a hot water cylinder specifically suited to heat pumps. However, once installed correctly, air-source heat pumps are cheaper to run than gas or oil boilers. The Energy Savings Trust estimates that the average homeowner will save around £500 a year in heating costs.

Depending on where in the UK you live, there may be some financial support for heat pump installations and, until March 2022, homeowners can also apply for the Domestic Renewable Heat Incentive (RHI) scheme which pays participants quarterly over seven years for the renewable energy they generate and use. These payments can help to recover some of the initial installation costs. Although the Domestic RHI is closing to new applicants next Spring, it is anticipated that a new scheme will be introduced by the Government to replace the RHI so that homeowners continue to have financial support made available to them when they make the move to greener heating systems.

Are there any downsides to consider?

Cost and noise are the two main concerns we hear when discussing heat pumps with potential customers. The fans on a heat pump do make a sound as they rotate, but there are quieter options like the Grant Aerona³. These heat pumps are quieter than appliances like washing machines or vacuums and even the average conversation!

Both our 13kW and 17kW Aerona³ heat pumps have been awarded the Quiet Mark, which recognises these products for their excellent performances and identifies them as being amongst the quietest models within their given category.

Do heat pumps still work when it’s really cold outside?

The idea that heat pumps don’t perform well in low temperatures is a misconception. In fact, sized correctly, heat pumps operate efficiently down to design temperatures (these will typically be -3 throughout England and Wales with -7 sometimes being allowed for in some areas of Scotland). Heat pumps will continue to work even when the outdoor temperatures drop to as low as -15°C.

Are there any other advantages to running an air source heat pump?

Yes! An air source heat pump will get around 65 to 70% of your energy from the ambient air, so they dramatically reduce carbon emissions. They also have a long lifespan - some manufacturer warranties extend as long seven years, which reflects their confidence in the product.

There is typically less maintenance required for an air-source heat pump and you don’t have to worry about flues, gas connections or, for those off-grid, fuel storage. All in all, they are a very reliable, and very clean, source of heat.

For more information about renewable energy and your choices visit www.energysavingtrust.org.uk and for more details on air source heat pumps, consumer guides and knowledge hub visit www.grantuk.com

Kevin Ellis has been working in the heating and plumbing industry for over two decades. He joined Grant UK in 2017 and heads their Renewables Sales Team, providing technical and customer support for their Aerona³ air source heat pumps and other renewable heating technologies.

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Watch how heat pumps have transformed the family home of The Selmans on Grant UK’s YouTube channel

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