HIU Service Cost in 2026: What You Should Pay

What we charge

These are our own fixed prices for Birmingham and the Black Country, not an industry average, and they are what you would actually pay us. Parts are the one thing that cannot be fixed in advance, and we deal with that by quoting them before anything gets fitted.

What each package actually includes

Essential — £95

The core checks every unit needs: a visual inspection, a strainer clean, pressure top-up, venting, temperature checks at the outlets, and a written report. This is the right choice for a unit that is still under warranty and has never given anybody any trouble. It keeps the warranty paperwork straight and it catches the two faults that cause most winter breakdowns.

Complete — £115

Everything in Essential, plus a secondary strainer clean, valve servicing, an inhibitor and expansion vessel check, minor leak repairs, and performance fine-tuning. This is what we recommend for most flats, and the extra £20 buys the parts of the job where problems are actually found rather than just confirmed.

Premium — £170

Everything in Complete, plus heat exchanger cleaning, full fault diagnosis and a thorough controls check. This is for an older unit, one that has never been properly stripped and cleaned, or one that has started to show reduced hot water performance. If your shower has quietly got weaker over a couple of years, this is the one that fixes it.

If you are unsure which tier applies to your unit, tell us its age and what it is doing when you book. We would rather put you in the right package than sell you the dearest one. Full detail on all three sits on our HIU service and repair page.

Emergency repair: £225

If the unit has already stopped working, that is a repair rather than a service and it is priced differently. £225 covers the callout plus up to three hours of labour to find and fix the fault. Three hours is enough for the large majority of HIU repairs, including stripping and cleaning strainers, swapping a sensor or an actuator, and re-commissioning afterwards.

Two things are handled separately and openly. Parts are quoted before they are fitted. And if a job is clearly going to run past three hours, we tell you before we carry on, so the number never quietly grows while we are in the cupboard.

Parts: the honest bit about pricing

Nobody can give you a fixed all-in repair price for a HIU over the phone, and anybody who does is either guessing or building a large margin into it. Until an engineer has the case off and can read the unit, the failed component is unknown. A temperature sensor and a plate heat exchanger are both "a part", but they are nowhere near the same money.

What you should insist on instead is the process: a fixed price for attending and diagnosing, a clear labour position, and a quoted price for any part before it is ordered or fitted. That is exactly how we run it.

What moves the price up or down

• The condition of the unit. One that has been serviced every year is a quick, predictable job. One that has never been touched in a decade takes longer, and the heat exchanger is far more likely to need cleaning.
• Access. Units crammed into a shallow cupboard behind a washing machine, or boxed in during a kitchen refit with no removable panel, add time. If yours is awkward, mention it when you book.
• Isolation valves. Servicing a HIU means isolating the primary side. Where the valves are seized or missing, the work becomes considerably more involved and sometimes needs the managing agent's agreement to isolate at riser level.
• Make and model. Some manufacturers' units strip down in minutes, others are considerably more awkward and use less common gaskets.
• Distance. We cover Birmingham and ten miles from B20 2JS as standard. Beyond that a travel charge may apply.

Blocks, portfolios and managing agents

If you look after a block or a portfolio of flats on a heat network, servicing them one at a time is the expensive way to do it. We service HIUs across multiple units on a single visit and issue a written report for each unit, which is what you need in order to evidence what has been done, flat by flat, when a resident or a freeholder asks.

A per-visit price for a block depends on how many units, how they are arranged, and access arrangements for getting into occupied flats, so we price those individually. What we would say is that the per-unit cost falls considerably once an engineer is not travelling between jobs, and that a coordinated round of servicing in early autumn causes a fraction of the disruption that a run of January breakdowns does.

How to compare two HIU service quotes

Price alone tells you very little here, because "HIU service" is not a defined term the way an annual gas boiler service is. A cheap quote can be a genuine bargain or it can be twenty minutes of looking at the unit and a tick sheet. Ask these questions of anyone quoting:

• Are the strainers being removed and physically cleaned, or just looked at?
• Is the plate heat exchanger being cleaned, and at what point does that become an extra?
• Do I get a written report, and does it record actual temperatures and pressures rather than just ticks?
• What is the labour rate if something is found, and are parts quoted before fitting?
• Will the paperwork satisfy my manufacturer's warranty conditions?

A £60 quote that does not include a strainer clean is more expensive than a £115 one that does, because you will be paying somebody again in February.

Who actually pays for it

This depends on your lease and your heat supply agreement, and it does genuinely vary between developments. The common arrangement is that the freeholder or heat supplier maintains the energy centre and the shared pipework, and the leaseholder is responsible for the HIU inside the flat and everything beyond it. On some newer developments the HIU is maintained under the heat supply contract and the cost sits in the service charge instead.

Before you book, it is worth two minutes checking your lease or asking the managing agent whether HIU maintenance is already covered. If it is, you should not be paying twice. If it is not, the responsibility is almost certainly yours, and a service is the cheapest part of owning one.

Is a HIU service a legal requirement?

No — not in the way an annual gas safety check on a gas appliance is a legal duty for landlords. There is no HIU equivalent of a CP12, because there is no combustion and no gas.

What there usually is, though, is a contractual requirement. Most manufacturers require documented annual servicing to keep the warranty valid, and many leases and heat supply agreements oblige the occupier to maintain the unit. For landlords letting a flat on a heat network, the practical argument is simpler still: a HIU that fails in December leaves a tenant with no heating and no hot water, and that is a repairing obligation you will be dealing with at short notice and at emergency prices.

Booking one

Send us a photo of the unit and its data label when you get in touch — WhatsApp is easiest — and tell us roughly how old it is and whether anything is currently wrong with it. That is enough for us to put you in the right package and turn up with the right gaskets and filters rather than making a second trip.

You can see the full package detail and book directly through our HIU service and repair service. If the unit has already stopped producing hot water, read HIU not heating water first — some of it you can check yourself in five minutes, for nothing.

Written by the engineering team at Synergy Gas & Plumbing, Gas Safe registered 594385. Last reviewed August 2026.