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How do heat pumps work?

Heat pumps capture naturally occurring heat from the ground or air and convert it into heat used for buildings.

4 min read

Gas and oil prices continue to rise, causing many to struggle to pay their energy bills. As there is no guarantee that bills will become cheaper, it is becoming ever more important to look towards energy sources that do not rely on gas or oil.

Heat pumps have become an increasingly common source of heat production, relying on heat naturally present in the ground or air to heat up buildings.

This article will go through the different types of heat pumps and how they work, as well as discussing the various advantages and disadvantages to buying a heat pump.

How does a heat pump work?

Heat pumps work on the basic rule that high temperatures naturally flow towards low temperatures. Existing technologies, such as refrigerators, also operate on this premise. By evaporating and compressing liquids, refrigerators remove heat from the inside.

Heat pumps reverse the process to bring heat into a building.

Types of heat pumps

All heat pumps use the same scientific premise to operate, though they draw their heat from different sources.

Air source heat pumps

These heat pumps take heat from the surrounding air, and transform it into heat for the building. This is done through the use of a compressor.

Using a fan, the outside air is channelled into the heat pump system and runs over a refrigerant - a liquid at a very low temperature.

The refrigerant is heated up by the outside air and by compression, which causes it to evaporate. The evaporation releases stored heat that will be used throughout your home, for heating or hot water. Air source heat pumps can also be used to cool a house, fulfilling the role of an air conditioning unit.

Ground source heat pumps

Ground source heat pumps work in the same way as their air source counterparts, but draw their heat from the ground or a nearby body of water.

They can either operate on a closed loop, using a continuous supply of refrigerating liquid, or on an open loop, so used intermittently.

Ground source heat pumps for important industrial or commercial buildings are called absorption heat pumps. They use ammonia, a chemical compound, in place of a refrigerant.

Since absorption heat pumps are difficult and costly to install, mini-split heat pumps are used for domestic purposes.

Pros and cons


Heat pumps are well suited to the UK’s climate, as they require only moderate temperatures to produce heat. They can even produce heat during the winter, so can generate heat all year long in the UK.

Technically, heat pumps aren’t a renewable source of energy, since they require electricity to function. Very little electricity is required, however, making heat pumps a generally “clean” source of energy.

Since little electricity is required, heat pumps are much cheaper than the gas or oil alternatives. With gas prices continuing to soar, reducing your dependence on gas is very much advised. Some estimates place yearly savings at £240.


Unfortunately, heat pumps aren’t suited to all buildings in the UK, as they require good building insulation in order to be effective. Older buildings that are prone to draughts are especially ill-suited to heat pumps.

In good news, however, many newly-constructed buildings are well-isolated, making them ideal for heat pumps.

To gauge whether your property is suited to a heat pump, ask for an Energy Performance Certificate (EPC). EPCs measure the energy efficiency of buildings, offering a rating of A to G. Lean more about EPCs here.

Heat pump units are quite noisy and blow the unwanted colder air into their surroundings. They also require some space, so make sure your property can house a unit before installation.

Heat pump efficiency

Despite not being a carbon-neutral energy source, heat pumps are very efficient in that they require little electricity to work.

Heat pumps are clearly more efficient than gas or oil heating sources, as these produce huge carbon emissions.

Bear in mind, however, that the efficiency of your heat pump is dependent on the model and brand that you buy. Heat pumps, by law, are required to have an energy label on them, indicating the energy efficiency of the unit.

Make sure that your heat pump has a good energy efficiency rating and that it is certified by the Microgeneration Certification Scheme, which certifies a high quality for low-carbon energies.

Government grants

Heat pumps can be quite expensive, so government grants have been put in place to lower your up-front costs.

Under the Boiler Upgrade Scheme, in place since April 2022, properties with good energy efficiency may be eligible for a £5,000 reduction on the price and installation of an air source heat pump and a £6,000 reduction on the price and installation of a ground source heat pump.

Eligibility requires that you live in England or Wales and that you are the owner of the property.

Learn more about the government’s Boiler Upgrade Scheme here.

Alongside the Boiler Upgrade Scheme, the UK Government has set up a £60 million Heat Pump Ready programme. Read more about it here.

Requiring onlyith little electricity, heat pumps convert natural heat into more intense heat used for hot water or central heating. Heat pumps remain a less carbon intense source of heat production than gas or oil and do not come with the same unaffordable energy bills.

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What is an air source heat pump?

An air source heat pump takes heat from surrounding air to transform it into more intense heat.

Are heat pumps carbon-neutral?

No, they are not, but they only require little amounts of electricity to function?

Are there grants available to install a heat pump?

Under the Boiler Upgrade Scheme, you may be eligible to receive money for the installation of a heat pump.

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