Heat pumps have a reputation for being low maintenance and that reputation is mostly earned. Compared to a gas boiler, air source heat pump maintenance is genuinely less involved. But less involved doesn’t mean none at all. A system that gets ignored for years becomes a system that quietly costs more to run than it should, and eventually something that was a small fix becomes a bigger one. Understanding what air source heat pump maintenance actually involves means you know what to do yourself and what to leave to someone qualified.
Most of what keeps a heat pump running well is simple. Some of it you can do yourself. The rest is handled in an annual professional visit. Here’s how it breaks down.
The Outdoor Unit
This is where most of the DIY side of air source heat pump maintenance sits, and it’s also the thing most people forget about because the unit just sits there doing nothing visible.
The outdoor unit pulls air across coils to extract heat from it. That process depends on good airflow. Leaves pile up around the base. Grass grows toward it. Ivy finds its way in if you leave it long enough. None of this announces itself as a problem, it just quietly reduces how effectively the system can do its job.
Every couple of months, walk around it and clear what’s built up. That’s genuinely all it takes most of the time. Keep a metre or so of clear space on the side where air goes in. After a frost or a decent snowfall, have a look at the coils. The system handles ice itself through a defrost cycle, but if there’s a heavy build-up that clearly hasn’t shifted on its own, that needs someone to look at it. If the coils are visibly dirty, a gentle rinse with a garden hose is fine. Turn the unit off first. Don’t touch it with a pressure washer.
Filters
Most heat pump systems have filters somewhere in the indoor unit or air handling components. They do the same job as filters in any air conditioning system: catch airborne dust and debris before it gets into the mechanism. And like any filter, they block up over time.
It’s recommended that you check the filters at least every month after using them to make sure they are kept clean, as dirty filters can result in mold building up which will lead to internal damage so it’s crucial that you check them yourself after some time . If they’re coated grey, clean them: vacuum off the bulk with a soft brush attachment, rinse under lukewarm water, after that leave them to try and only refit when they have fully dried.
Air source heat pump maintenance that lets the filters go is one of the quieter ways efficiency drops. It doesn’t cause a sudden problem, it just makes the system work harder than it needs to for longer than it should.
Refrigerant and Pipework
The refrigerant circuit is sealed. It shouldn’t need attention between services. If the system starts losing efficiency and everything else checks out, low refrigerant is something an engineer will look at. Refrigerant work is F-gas regulated and has to be done by someone qualified. There’s no DIY version of this.
What you can check yourself is the pipework connecting the two units. Look for damage to the insulation, any joints that look like they’ve been disturbed, or wear that’s crept in over time, particularly on any exposed sections. Insulation on refrigerant pipes matters more than people realise and it does degrade, especially outdoors.
The Heat Exchanger Coils
The coils on the outdoor unit collect dirt over time, more so in areas with high pollen, near agricultural land, or anywhere with a lot of airborne dust. Dirty coils mean less efficient heat transfer, which means the system works harder for the same output.
Coil cleaning is part of a proper annual service. Between services, a visual check and a careful rinse if they’re visibly dirty is something you can do yourself. Turn the unit off, use a hose on a gentle setting, work with the fins rather than against them.
What the Annual Service Covers
The things you can do yourself are the surface-level tasks. An annual service from a qualified engineer goes further: refrigerant pressure, electrical connections, controls calibration, defrost cycle testing, overall system performance. These need the right equipment and the right training.
If the system is under warranty, servicing is almost always a condition of keeping that warranty valid. Even without a warranty, it’s what catches the issues that DIY maintenance doesn’t reach. Air source heat pump maintenance split between regular homeowner checks and annual professional servicing is what keeps a system running at the efficiency it was designed for.
Air Conditioning Direct has been installing and maintaining heat pump systems across London, Essex, Hertfordshire, and Kent for over 25 years. We cover residential and commercial systems, all engineers are fully qualified, and we offer up to a 7-year guarantee on selected equipment. More on our heat pump services here.
Seasonal Checks
Before winter: Clear the outdoor unit, check filters, make sure the defrost cycle is working. The system works harder in the cold and going in clean makes a real difference.
After winter: Check pipework insulation for damage, clear anything that’s accumulated around the unit through the colder months, rinse the coils if they’ve collected debris.
Through summer: If the system is running for cooling, check filters more often. Dust builds up faster during heavy use periods and consistent air source heat pump maintenance through summer keeps efficiency where it should be.
Things Worth Paying Attention To
Ice on the outdoor unit that the defrost cycle isn’t clearing. Noise that wasn’t there before. The system runs noticeably longer to hit the target temperature. Energy use goes up without an obvious change in how the house is being heated or cooled.
None of these mean something has definitely gone wrong, but all of them are worth a call rather than leaving until the next service. Air source heat pump maintenance works best when small things get looked at before they become bigger ones.
For anything that needs a qualified engineer, get in touch and we’ll come out.