Do Heat Pumps Need Servicing?

There is no gas to leak and no flue to check, so plenty of new heat pump owners assume the annual service they were used to with a boiler no longer applies. Legally they are half right: a heat pump has no equivalent of the gas safety inspection. In practice, skipping the service is one of the easier ways to lose both efficiency and your warranty cover.

Here is what the visit involves, what it is really protecting, and what you can sensibly keep an eye on yourself.

Why the warranty is the main reason

Most manufacturers tie their longer warranties to evidence of annual servicing by a competent engineer. The exact wording varies by brand, and the detail matters: some require registration within a set window after commissioning, some require a magnetic filter to be fitted and cleaned, and some specify the service must happen within a couple of months of the commissioning anniversary each year.

Miss those conditions and you are usually not left with nothing, but you can drop back to the short base warranty rather than the extended cover you were sold. On a unit that is the single most expensive item in your heating system, that is a poor trade for one missed appointment. Check your own paperwork, because the conditions sit in the manufacturer’s terms rather than anything we or any other installer decides.

What an engineer actually checks

A proper heat pump service is mostly about water, airflow and data, not combustion.

The magnetic filter gets cleaned out, which on a retrofit to older radiators is often where the debris shows up. System pressure, the expansion vessel and the inhibitor level are checked, because a heat pump running on a system losing pressure or short of inhibitor will corrode and sludge up like any other wet heating system.

Outside, the engineer clears the evaporator coil and the grille of leaves and dust, checks the condensate drain is clear and running away properly, and looks over the unit and visible pipework for corrosion, leaks and damaged insulation.

Then comes the part that earns its money: reading the controller. The error log, the flow and return temperatures, the weather compensation curve and the actual running performance over the past year tell an experienced engineer whether the system is sitting where it should be. Plenty of underperforming heat pumps are not faulty at all, they have simply been left running at a higher flow temperature than they need, which is exactly what drags a SCOP down from near 4 towards 2.5. On grid electricity at around 24p per kWh, correcting that pays for several services.

Anything involving the sealed refrigerant circuit is a separate matter: that work is restricted to F-gas certified engineers by law, so it is worth using someone qualified on heat pumps specifically rather than a general plumber.

What it costs and how often

Once a year is the standard interval, and typical market rates sit somewhere in the region of £150 to £250, broadly in line with a boiler service and taking a couple of hours. Some owners fold it into a cover plan, others book it as a one off. Either is fine, as long as you keep the paperwork, because the written service record is what satisfies the warranty condition.

The bits you can do yourself

Between visits, four small habits keep a heat pump honest.

Keep the outdoor unit clear. It needs free airflow, so no stacked garden furniture, no new fence panel tight against the grille, and shrubs trimmed back. Brush leaves away from the coil in autumn.

Keep an eye on the condensate drain in cold snaps, where a blocked or frozen outlet is a common winter call out.

Glance at the system pressure gauge every month or two, the same as you would with a boiler, and ring your installer if it is dropping.

Finally, leave the controls alone once they are set. A heat pump holding a steady temperature on a properly commissioned compensation curve is doing the economising for you.

When to call sooner

Book a visit outside the annual cycle if the unit starts icing up heavily and staying iced, if it is noticeably noisier than it was, if hot water or heating recovery has slowed, or if the electricity use has climbed without the weather explaining it. These are all cheap to look at early and expensive to ignore.

If you are weighing up a heat pump and want to know what it would cost to run, service and own in your own house, including what the £7,500 Boiler Upgrade Scheme grant leaves you to pay, our survey is free and carries no obligation.