What a boiler repair usually costs
Most boiler repairs in the UK cost £150 to £450 for the part and labour, and finding the fault typically costs £80 to £120. The price depends mostly on which part has failed, not on where you live or which engineer you call. These are typical national prices, checked October 2026.
Typical prices by job
| Job | Typical price | Typical visit |
|---|---|---|
| Diagnostic visit | £80 to £120 | about 1 hour |
| Pump replacement | £150 to £350 | 1 to 3 hours |
| Diverter valve replacement | £150 to £350 | 1 to 3 hours |
| Fan replacement | £150 to £350 | 1 to 3 hours |
| Main circuit board (PCB) | £250 to £450 | 2 to 3 hours |
| Annual boiler service | £80 to £120 | about 1 hour |
The part and the labour are usually quoted together as one price. If a quote splits them, add them up before you compare.
What each fault looks like
Pump. The pump pushes hot water round your radiators. When it fails you often get a boiler that fires up and gets hot, but radiators that stay cold or only warm near the top. Sometimes there is a humming or grinding noise.
Diverter valve. On a combi, this valve switches hot water between the radiators and the taps. A failing one gives you heating but no hot water, or hot water that turns lukewarm whenever the heating is on.
Fan. The fan clears waste gases out through the flue. If it fails the boiler shuts itself down for safety and shows a fault code. A noisy, rattling fan is often a warning sign before it stops.
Main circuit board (PCB). The printed circuit board is the boiler’s brain. A failed board can cause almost any symptom, which is why a good engineer rules out cheaper parts first. Ask how they confirmed it is the board before you pay for one.
Heat exchanger. This is where the burner heats the water, and it is the most expensive part in most boilers. A leaking or cracked heat exchanger on an older boiler is usually the point where replacement makes more sense than repair. See repair or replace your boiler before agreeing to one.
Pressure faults. A leak, a worn pressure relief valve or a flat expansion vessel can all make pressure drop. Some of these are simple to fix and some are not. Our guide to a boiler losing pressure covers the safe checks you can do first.
What pushes the price up or down
- The make and model. Parts for common, current boilers are cheaper and easier to get. Parts for older or discontinued models can cost more and take days to arrive.
- Whether the part is on the van. Pumps and diverter valves often are. A circuit board usually is not, which can mean a second visit.
- Access. A boiler in a tight cupboard or loft takes longer to work on.
- Out-of-hours visits. Evenings, weekends and bank holidays usually cost more. If you have hot water or some heating, a weekday slot is often the cheaper option.
- Whether the call-out is credited. Many engineers deduct the diagnostic fee if you go ahead with the repair. Some do not. Ask first.
Check your warranty before you book
If your boiler is still under its manufacturer warranty, call the manufacturer before anyone else. Most warranties cover parts and labour, but only if the boiler has had a service every year. Paying an independent engineer to fix a fault that the manufacturer would have covered is money you will not get back. Our page on the annual boiler service explains why the service record matters.
How to read a repair quote
A good quote names the fault, the part being replaced, the total price including VAT, and how long the repair is guaranteed. If it just says “boiler repair”, ask for the detail in writing.
Before you agree:
- Ask how the fault was diagnosed. “The board has gone” should come with a reason.
- Ask whether the part is genuine manufacturer stock.
- Ask whether the diagnostic fee comes off the final bill.
- Check the engineer’s Gas Safe ID card. Our guide shows how to check an engineer is Gas Safe registered.
Repairs you can avoid paying for
Some call-outs turn out to be things you could have checked yourself in five minutes: low pressure, a thermostat set too low, a tripped fused spur, or a frozen condensate pipe in a cold snap. Our guide to a boiler not firing up lists the safe checks, in the order an engineer would do them. Anything involving gas or the inside of the boiler still needs a Gas Safe registered engineer.
When the repair bill stops making sense
On a boiler over 12 years old, a £250 to £450 board or a heat exchanger can be a poor use of money if another part is likely to go next winter. A like-for-like combi swap typically costs £2,200 to £3,400 fitted, checked October 2026. If you have had two or three repairs in two years, put that number next to the repair quote before you decide.
City Boiler connects you with independent local engineers who are Gas Safe registered. More on what a repair visit involves is on the boiler repair page.
Common questions
What is the average cost of a boiler repair?
Most repairs fall between £150 and £450 including the part and labour, on top of or including a diagnostic visit of £80 to £120. A circuit board sits at the top of that range. These are typical national prices, checked October 2026.
Do engineers charge for a call-out if they cannot fix it?
Usually, yes. The diagnostic visit pays for the engineer's time finding the fault. Many engineers knock it off the bill if you go ahead with the repair, so ask before they visit.
Is a boiler repair covered by my warranty?
If the boiler is still under its manufacturer warranty and has been serviced every year, the manufacturer usually sends its own engineer and covers parts and labour. Call the manufacturer before booking anyone else, or you may end up paying.
Why is a circuit board so expensive?
The board is the boiler's control unit and is specific to the model, so the part itself is the main cost. Fitting it also means setting it up for your boiler, which takes two to three hours.