What is a heat pump and should you get one?

Prime Minister Boris Johnson has announced a £450m fund to install heat pumps in homes as part of the government’s Heat and Buildings strategy.

The strategy aims to incentivise people to replace their old boilers with low-carbon heating systems in an effort to reduce the UK’s dependence on fossil fuels. 

What is a heat pump and how does it work?

A heat pump is one of the most energy efficient devices available to heat a building. Instead of using fuel to raise the temperature like a boiler, they work to transfer warmth from one area to a cooler area. They can also be used to transfer heat in the opposite direction and cool buildings down.

What’s the difference between an air source and ground source pump? 

There are three common types of heat pump: air source, ground source and exhaust air.

An air source heat pump works like an air conditioner, using outside air as a heat source when it’s cold inside. They often work as air conditioners too, transferring heat in the opposite direction in the summer months.

But you don’t need to live in the tropics to warm your home using an air source heat pump. Some manufacturers have made sure their devices can heat a home using outside air even in sub-zero temperatures.

A ground source heat pump uses the earth beneath a building as its heat sink or heat source. While the air can change temperature dramatically depending on the season, there is relatively little fluctuation underground.

A ground source heat pump sends a special heat-transferring liquid underground to absorb the warmth. This liquid then warms water for use in a radiator system or air in central air conditioning systems.

The third most common – and least efficient –  type of heat pump is an exhaust air heat pump. These use warm air leaving a building as a heat source for radiators or water.

What are the advantages of a heat pump?

Heat pumps are most often talked about as a green alternative to gas boilers which use fossil fuels and emit greenhouse gases. 

They certainly are, but the advantages extend beyond that too. For starters, they’re much cheaper to run and maintain once set up. Thanks to being energy efficient, they could save households upwards of £1,000 per year on bills.

Heat pumps also require less maintenance than traditional boilers, and tend to have a longer life span. 

What are the disadvantages of a heat pump?

For many years the up-front cost of a heat pump has been the main barrier to their use. The units themselves and the price of installation have far outstripped traditional gas or immersion boilers, but that is set to change.

Some questions have also been raised about the true eco-credentials of heat pumps.

Some of the fluids used for heat transfer are considered unsustainable, while heat pumps also rely on electricity to operate.

If the source of electricity is non-renewable, this means carbon emissions are still being produced to run it. 

How much does it cost to install a heat pump?

The government’s voucher scheme will see homeowners given £5,000 towards the cost of installing heat pumps.

One energy firm, Octopus Energy, has estimated that this would mean homeowners contributing around £2,500 to the initial cost of installing a heat pump – roughly the cost of a new boiler.

However, houses with low energy efficiency are likely to need an upgrade to their insulation before they can install a heat pump.

The new scheme will run alongside funding packages like the Social Housing Decarbonisation Fund and Home Upgrade Grant which aim to help low-income and vulnerable households with the cost of installing low-carbon measures and improving energy efficiency.

How can I access the scheme? 

The £5,000 grants for homeowners will be available from April 2022. 

It’s not yet clear whether the grant will be available for installation of heat pumps only – with the government saying the grants will be available to encourage installation of “more efficient low carbon heating systems”

Further information on how to apply for a grant will be provided closer to the scheme’s opening date.