What is a heat pump, how does it work, and why it's more expensive than a boiler—even with the government's new grant

Heat pump grants are set to replace boilers after government funding commits to subsidize low-carbon heat pumps in England and Wales from April 2022.

The UK is currently suffering from an Energy Crisis. This means that many of us are worrying about where to get petrol and wondering if we should delay turning the heating on.

In response to this issue and in a bit to tackle climate change, the government announced that heat pumps would be a new low-emission cure to the current gas boilers that are used across the UK.

To learn more about this issue, woman&home spoke to Mike Foster, CEO of the Energy and Utilities Alliance, who explained exactly what a heat pump is, and how beneficial these appliances really are.

What is a heat pump? And how does it work?

Mike explained, "A heat pump is an appliance that can generate heat by transferring energy from a cool environment to a warm environment using a refrigeration cycle. It takes the cold air from outside and uses electricity to create heat which can then be used for a central heating system and to fill a hot water cylinder."

In simple terms, the heat pump is a bit like a fridge and takes cold air and transforms it into warm air. The unit typically looks like a standard air conditioning unit and is typically located on the site of a house. 

Do heat pumps still work in cold weather?

Mike says that although heat pumps do work in cold weather, they work more efficiently in warmer weather.

"Heat pumps will work in cold weather but their efficiency falls as the outside temperature drops. It will perform more efficiently with an outside temp of +4 degrees centigrade compared to -4 degrees centigrade."

Mike added that insulation is key to efficiency, "To make heat pumps work in homes a property must be extremely energy efficient. That will include loft insulation, double glazing, cavity wall insulation (or external wall cladding), and possibly underfloor heating."

Are air source heat pumps noisy?

Yes, heat pumps can be very loud, and therefore they may not be suitable for every household. Mike explained why sometimes these appliances can be so noisy.

"There are several parts to a heat pump. The internal parts, control unit, buffer tank, and hot water cylinder are noiseless, but the outside or external unit where the fan operates to generate the heat exchange can be noisy," says the expert.

He further explained, "because of the planning requirements around noise levels, the government has highlighted the fact that heat pumps might not be suitable for smaller homes in more densely concentrated housing estates such as terraced houses."

This means that heat pumps may not be a viable option for all homeowners.

What is the cost of installing a heat pump in the UK?

Mike tells woman&home that the installation of a heat pump can be a big cost. He says, "The government estimate that the cost is about £10,000 to install a heat pump, not including insulation measures that might be needed to be fitted in advance of the heat pump, such as external wall cladding.

"Because a heat pump operates at a lower temperature to gain the efficiency it might mean that radiators have to be changed and bigger radiators fitted. If you do not have a hot water cylinder you will have to find space to have one fitted as a heat pump will not produce instantaneous hot water," said Mike.

This suggests that installing a heat pump may actually be a rather hefty sum and although the £5,000 may help with costs, there are other factors that need to be addressed by those considering making a switch.

How much does a heat pump cost to run?

The expert says that the figure of running a heat pump with be totally dependant on the size and quality of your property.

"The running costs of a heat pump will be determined by the size of your home and how warm you want each room to be. Based on average demand levels for heat, a heat pump will currently cost you about £250 more per year to run than a modern condensing gas boiler," said Mike.

Does the government's grant for heat pumps to replace gas boilers make them cheaper than a conventional boiler?

"The government’s grant of £5000 halves the cost of a heat pump for the first 30,000 voucher applicants. But even paying the remaining £5000 is still more than twice what it will cost for a like-for-like replacement of your gas boiler. 

"It is not a solution that most people can currently afford even if their home is thermally efficient and suitable for a heat pump," said Mike.

This means that heat pumps may not be a great option for many people who live on a tight budget, or those who live in a more densely populated area.