What's Included in an Air Source Heat Pump Service? A Full Checklist

A proper air source heat pump service is a great deal more than a quick look and a wipe-down. Done correctly, it's a structured, dozen-point check of the refrigerant circuit, the water side, the electrics, the controls and the safety devices — with a written record at the end. This guide walks through exactly what should be on the checklist, so you know whether the service you're paying for is the real thing.

What's included in an air source heat pump service? (the short version)

A thorough ASHP service should cover, at minimum:

• Refrigerant operating pressures and overall performance

• A refrigerant leak check where required

• Glycol / antifreeze strength, plus a top-up if needed

• System pressure, filters and the magnetic filter

• The condensate drain

• Electrical connections and safety devices

• Controls, weather compensation and sensors

• Cleaning the outdoor unit, coils and fan

• A full safety check

• A written service report

Below, here's what each of those actually involves — grouped the way a good engineer works through the system.

1. Refrigerant circuit & performance

This is the heart of the heat pump — the part that actually moves heat from outside to inside.

• Operating pressures and performance check. The engineer measures how the refrigerant circuit is performing against expected values, so any drop in output is spotted early.

• Refrigerant leak check (where required). Any work on the sealed refrigerant circuit legally requires an F-Gas certified engineer. Leaks quietly kill efficiency and can damage the compressor.

• Flow temperatures and efficiency. Checking the temperatures the system is producing confirms it's running efficiently rather than working harder — and costing more — than it should.

2. Water side & antifreeze

The water (or water-glycol) side carries the heat around your home, and it needs looking after just as much as the refrigerant side.

• Glycol / antifreeze strength and top-up. The inhibited antifreeze that protects your system from freezing and corrosion weakens over time. It's tested and topped up so your heat pump is protected through winter.

• System pressure and expansion vessel. Correct pressure keeps everything circulating properly; the expansion vessel is checked so pressure stays stable as the system heats and cools.

• Filters and the magnetic filter. These trap sludge and debris that would otherwise choke flow and drag down efficiency. Cleaning them is one of the highest-value parts of a service.

3. Electrical & controls

Much of what you pay to run a heat pump is decided by its settings — so a good service is as much about optimisation as inspection.

• Electrical connections and safety devices. Terminals, wiring and protective devices are inspected and checked for safe, secure operation.

• Controls, weather compensation and sensors. Heating curves, schedules and sensor readings are reviewed so the system delivers the heat you need at the lowest running cost. Badly set controls are one of the most common reasons a heat pump costs more than it should.

• Firmware and error-log review. The controller's logs are checked for warnings or intermittent faults that don't show up as an obvious breakdown but point to something worth addressing.

4. Physical unit, drainage & safety

Finally, the parts you can see — and the checks that keep everyone safe.

• Outdoor unit, coils and fan cleaned. Leaves, dust and debris are cleared, and airflow and clearances around the unit are checked, so it can breathe and work efficiently.

• Condensate drain cleared. A blocked or frozen condensate can cause water to back up and faults to trip; it's cleared and checked.

• Full safety check. A final sign-off that the system is operating safely and correctly across the board.

The bit many "services" skip — the written report

Here's how to tell a proper service from a token visit: you should get a written service record. It documents the readings taken, the work carried out and any recommendations, and it forms the service history your warranty depends on. No paperwork means no proof the service happened — which can matter enormously if you ever need to make a warranty claim.

A good report also lets you track your heat pump's performance year on year, so a gradual drop-off gets caught before it becomes a problem.

What a heat pump service does not usually include

To be clear and fair: a standard service is an inspection, clean and optimisation — it isn't a repair. It doesn't normally include the cost of replacement parts, or major component repairs, unless your plan specifically includes labour. If the engineer finds something that needs fixing, they'll flag it and quote for it. On our labour-inclusive plan, the labour to put things right is covered; parts remain separate.

Can I do any of this myself?

You can — and should — handle the basics between services: keep the outdoor unit clear of leaves and debris, make sure nothing blocks the airflow, and keep half an eye on your pressure gauge. But the checklist above needs a qualified engineer, and anything involving the refrigerant circuit legally requires F-Gas certification. It isn't a DIY job — and a professional has the instruments to measure what you simply can't see.

How Renewable Helpline services your heat pump

Renewable Helpline is a specialist air source heat pump maintenance service — this is all we do. Every plan includes a full annual service to the checklist above, carried out by ASHP specialists, with a written record for your warranty file:

• Essential Care — from £15/month: your full annual service, plus support when you need it.

• Complete Care — £18/month (most popular): everything in Essential Care, with your hot water cylinder covered too.

• Priority Care — £30/month: our most comprehensive plan, with labour included.

Plans are for mainland UK private domestic properties, with a 12-month minimum term — and they mean your service is booked, done and documented, without you having to chase it.

Want the full checklist done properly? Call 0800 135 7663 or email hello@renewablehelpline.co.uk.

Frequently asked questions