How to service a heat pump – a maintenance guide to keep it running efficiently

Installing a heat pump can save you money on utility bills. However, to maximise those savings, you want it to run as efficiently as possible. That's why knowing how to service a heat pump matters. 

It is a specialist job so make sure that you book an engineer who’s a heat pump expert. And while you can’t do the annual service yourself, you can keep costs down with DIY care.

‘The better maintained a heat pump, the more efficiently it performs, just like any heating system,’ says Joseph Raftery, Heating Product Manager, Samsung Climate Solutions. He also highlights that annual services are usually essential to keep the warranty of a new heat pump valid.

How to service a heat pump

Heat pumps extract heat from via air source or ground source, outside our homes, and bring it indoors to heat a tank of water. They transfer it by expanding and compressing a refrigerant as it moves through pipes. There’s equipment both outdoors and indoors that needs routine maintenance.

Knowing what to do, depends on the type of heat pump you have.

Air source heat pump maintenance

With air source heat pumps, there are no components that need routine replacement, but you do need regular cleaning of debris plus annual checks that pumps are working and the system’s pressures are correct.

Kaspar Bradshaw of Next Step Heating talks us through the routine maintenance:

1. Brush the fins

‘The heat exchanger fins at the back of the heat pump need careful cleaning with a brush, particularly if they are below trees.’

2. Clean the magnetic filter

‘The magnetic particle filter needs removing and cleaning out. This captures corroded iron particles which would otherwise block the heat exchanger. If this is left uncleaned for too long, it can reduce the system flow rate and cause problems with the heat pump compressor as well as all other components.’

3. Check the expansion vessels, valves and settings

‘The heating and hot water expansion vessels must be checked to ensure they are at the right pressure. All safety valves need checking on the heating and hot water system. And all settings need careful checking to make sure the system is still working optimally.’

4. Check levels, filters and strainers

Steve Alldritt, Technical Director at Energy Efficiency at City Plumbing, adds that a service should include checking refrigerant levels. ‘Filters and strainers should be checked for debris or blockages that can affect the system flow rate. And if glycol (antifreeze) is being used, levels should be checked and topped up as necessary.’

Ground source heat pump maintenance

Steve Alldritt says ground source heat pump maintenance and servicing needs are as above, but that the collector array (the pipe in the ground) will definitely contain glycol and this level should be checked and topped up, in line with the heat pump manufacturer’s specification.

Kathryn Warren, Associate Director of Ricardo Energy and Environment business unit, has a ground source heat pump herself. She says her annual service also includes checks for everything from leaks to bacteria.

How much does it cost to service a heat pump?

Costs for an air source heat pump are comparable to how much does it cost to get a gas boiler serviced.

‘Services should be conducted annually and cost starts at around £140 including vat,’ says John Gilham, Group Technical Manager at Green Building Renewables. ‘Fewer engineers are specialised in heat pump services. You must ensure your service is conducted by someone who installs and maintains heat pumps.’

Kathryn Warren says that she expects to pay around £250 for the annual service of her ground source heat pump.

How easy is it to service a heat pump yourself?

‘If you know what you are doing, it can be very simple to maintain a heat pump,’ adds John Gilham. ‘However, we recommend that you always use a specialist who understands the setup and running of a heat pump.’

‘Simple tasks like cleaning the back of the heat pump can be done by the homeowner,’ adds Kaspar Bradshaw. ‘But servicing the heating and hot water system must be carried out by a competent person, as otherwise a small problem can quickly escalate into a more significant one.’