An air source heat pump needs an annual service by a qualified engineer, plus a few simple checks by you through the year. Servicing keeps the system running efficiently, picks up small problems early and is often a condition of the manufacturer's warranty.
Heat pumps have no flame, flue or fuel supply, so there is less to wear than in a combustion boiler, but they still need regular attention. This guide covers what a service involves, what you can safely do yourself, how warranties work, the signs that something is wrong and typical costs.
What does an annual heat pump service involve?
An annual heat pump service is a set of checks on the outdoor unit, the heating water circuit, the hot water cylinder and the controls, to make sure everything is safe and working as designed.
- Inspecting and cleaning the outdoor unit's coil and fan, and clearing debris
- Checking the condensate drain, the base, and the feet or mountings
- Checking refrigerant circuit performance from temperatures and pressures; on split systems, any refrigerant work must be done by an F-gas certified engineer
- Checking system water pressure and the expansion vessel
- Cleaning the strainer or magnetic filter that catches debris in the heating water
- Checking glycol strength or frost protection valves on monobloc pipework
- Testing the cylinder's safety valves and expansion vessel, and the legionella cycle settings
- Checking electrical connections, controls, error logs and software
- Checking flow temperatures and the heating curve, and suggesting adjustments
You should receive a written record of what was checked. Keep it with your installation paperwork, because you may need to show it for a warranty claim.
How much does a heat pump service cost?
A typical annual heat pump service has a guide price of £120–£250, including VAT.
| Visit | Guide price inc VAT | Notes |
|---|---|---|
| Annual service | £120–£250 | A paid visit, usually once a year |
| Fault-finding visit (first hour) | £90–£180 | Charged at a rate agreed before we attend |
| Repairs | £90–£1,100 | Depends on the part and labour; quoted after diagnosis |
Prices depend on the type of system, access to the outdoor unit and whether parts or extra work are needed. If a repair is needed, you are told the cost before work goes ahead. See heat pump servicing and heat pump repairs.
What maintenance can I do myself?
Owners can safely keep the outdoor unit clear, watch the system pressure and keep an eye on how the system is running; anything inside the unit or on the refrigerant circuit is a job for an engineer.
- Keep the unit clear. Remove leaves, snow, plant growth and anything stored nearby, so air can flow freely through the coil and out of the fan.
- Do not cover it. Covers and tight enclosures block airflow, especially in winter when the unit needs to defrost.
- Check the pressure. Look at the pressure gauge now and then and compare it with the range you were shown at handover. If it keeps dropping, ask for a check.
- Watch for ice. A light frost that clears during defrost is normal. Thick ice that does not clear is not.
- Keep the drain clear. Make sure condensate drains away and is not pooling or freezing on a path.
- Clean the strainer only if shown how. Some installers show owners how to clean the strainer or filter. Do it only if you have been shown, with the power isolated and following the instructions.
Never remove the unit's panels, touch the electrics or attempt any work on the refrigerant circuit. Do not jet-wash or brush the coil, because its thin fins bend easily and that reduces airflow.
Is annual servicing a condition of the warranty?
Annual servicing is often a condition of a heat pump manufacturer's warranty, so missing a service can affect your cover.
Manufacturer warranties pass to you — the length depends on the make and model — and our workmanship guarantee is set out in writing in your quote. Warranty terms commonly require the product to be registered with the manufacturer, serviced at set intervals by a competent engineer and repaired with approved parts. Read your warranty documents so you know exactly what is required.
Keep your MCS certificate, commissioning records and every service record together. If something goes wrong, these are what a manufacturer or engineer will ask to see first.
What are the signs that something is wrong with a heat pump?
The main warning signs are rooms that will not warm up, error codes on the controller, unusual noises, ice that does not clear, falling system pressure and a sudden rise in electricity use.
| Sign | What it might mean | What to do |
|---|---|---|
| Radiators lukewarm and rooms cold | Settings, low water pressure, a blocked strainer or a fault | Check pressure and settings, then ask for a check |
| Error code on the controller | The unit has detected a problem | Note the code and contact your installer or engineer |
| Rattling, grinding or loud buzzing | A loose panel, a fan problem or a unit off level | Switch off if the noise is severe and arrange a visit |
| Thick ice that does not clear | Defrost not working, blocked airflow or low refrigerant | Check the unit is clear, then ask for a check |
| Pressure keeps dropping | A leak in the water circuit or a faulty expansion vessel | Arrange a visit rather than topping up repeatedly |
| Water around the cylinder or indoor unit | A leak or a safety valve discharging | Isolate if safe to do so and call for help |
| Electricity use jumps | The immersion or backup heater running more, or wrong settings | Check schedules and settings, then ask for a check |
Most problems are found with a fault-finding visit, charged at a rate agreed before we attend. Many are put right with a settings change or a single part.
How long does an air source heat pump last?
An air source heat pump typically lasts 15–20 years, and regular servicing gives it a better chance of reaching the upper end of that range.
The outdoor unit works hardest and is usually the first part to need replacing. The cylinder, pipework, radiators and controls often last longer and can stay in place when the unit is replaced. A like-for-like replacement of an old outdoor unit has a guide price of £6,000–£9,500, installed including VAT. See heat pump replacement.
Signs that replacement may be worth considering include repeated breakdowns, a major part such as the compressor failing on an older unit, parts that are no longer available, or efficiency that has dropped despite servicing. An engineer can set the cost of a repair against the age of the unit so you can decide.
Questions
How often should a heat pump be serviced?
Once a year is the usual recommendation, and annual servicing is often a condition of the manufacturer's warranty. Many owners arrange the service in late summer or autumn, so the system is checked before the heating season starts. Your warranty documents set out the exact interval required for your make and model.
Does a heat pump need a gas safety check?
No. A heat pump does not burn fuel, so it does not need a gas safety check. If you have a hybrid system, or other gas appliances in the home, those still need their own servicing and safety checks. Landlords should check their legal duties for any gas appliances that remain in a let property.
Can any engineer service my heat pump?
A heat pump should be serviced by an engineer trained on heat pumps, ideally on your make and model, so the warranty is not affected. Any work on the refrigerant circuit of a split system must be done by an F-gas certified engineer. Check your warranty terms, which may say who can carry out servicing.
What should I do if my heat pump stops working in winter?
First check the controller for an error code, the system pressure and the power supply. Many cylinders have an immersion heater that can provide hot water in the meantime. Then arrange a fault-finding visit, charged at a rate agreed before we attend. Response times are typical, not fixed, and depend on demand and location.
Sources
Scheme figures and price cap rates checked October 2026.