Central Heating Repair Cost 2026
Most central heating repairs cost between £150 and £600, and the symptom usually tells you which end you are at. A radiator cold at the top is trapped air and often free to fix; cold at the bottom means sludge and points at a flush. Here are the 2026 ranges by job, what each symptom actually means, and how to judge a quote.
How much does central heating repair cost?
Most central heating repairs fall between £150 and £600. The range is set by whether the fault is a single component, a system-wide problem such as sludge, or a leak that has to be traced before it can be fixed. These are ranges rather than prices — the diagnosis decides where you land.
| Job | Typical range | What moves it |
|---|---|---|
| Bleed & rebalance system | £80 – £150 | Number of radiators |
| Radiator valve replacement | £100 – £200 | Access, and whether the system must be drained |
| Replace a radiator | £150 – £400 | Size, type, and pipework changes |
| Circulating pump replacement | £250 – £450 | Pump spec and location |
| Leak trace & repair | £150 – £600 | Finding it is the variable, not fixing it |
| Power flush | £400 – £800 | Radiator count and how bad the sludge is |
These are ranges, not a quote — a heating engineer has to diagnose the fault first. Get my exact price →
What you are actually paying for: call-out, labour and parts
A heating repair bill breaks down into the same three parts every time, and a fair quote separates them rather than giving one round figure.
- Call-out or diagnostic fee — typically £60–£120, often deducted from the bill if you go ahead. On a leak, this covers the tracing work, which is usually the hard part.
- Labour — most heating engineers charge roughly £40–£80 an hour, or £150–£300 for a half to full day. Bleeding and rebalancing is an hour or two; a power flush is most of a day.
- Parts and materials — a radiator valve is often £15–£40, a thermostatic valve £20–£60, a circulating pump £80–£200, and a replacement radiator £40–£250 depending on size and type. Cleaning chemicals and inhibitor for a flush add a little more.
Because a leak trace or a badly sludged system can run into hours, those are the jobs where quotes vary most — and where getting more than one price on the same described symptom matters most.
Read your radiators: what the symptom tells you
Central heating faults announce themselves fairly clearly if you know what to look for. Working this out before you call saves diagnostic time — and lets you judge whether a quote makes sense.
| Symptom | Usual cause | Typical fix |
|---|---|---|
| Cold at the top, warm below | Trapped air | Bleed the radiator — often free |
| Cold at the bottom, warm above | Sludge and corrosion debris | Chemical or power flush |
| One radiator cold, rest fine | Stuck valve or airlock | Valve free-off or replacement |
| Upstairs hot, downstairs cold (or vice versa) | System out of balance, or failing pump | Rebalance, or pump replacement |
| Banging or kettling noises | Limescale or sludge in the boiler | Flush, and check water treatment |
| Pressure keeps dropping | Leak somewhere in the system | Leak trace — the cost variable |
Repair, flush, or replace the system?
- Repair when the fault is one component and the rest of the system is sound. Most call-outs are this.
- Flush when several radiators are cold at the bottom, the boiler is noisy, or you are fitting a new boiler to old pipework — many boiler warranties require the system to be cleaned first, and skipping it can void the cover.
- Replace the system when pipework is failing in multiple places, the system is microbore and repeatedly blocking, or you are already reconfiguring the house. Our central heating installation guide covers that job and its costs. Where the failures are in the pipework rather than the heating itself, our plumbing cost guide sets out what re-runs and buried-leak repairs typically come to, and if you are reconfiguring the system anyway it can be the moment to weigh underfloor heating against swapping out tired radiators — a bigger job up front, but one that runs at a lower flow temperature and pairs well with a future heat pump.
Getting a fair quote
- Insist on a diagnosis before a price — anyone quoting a power flush without seeing the radiators is guessing.
- Ask what happens if the flush does not fix it: a good engineer will tell you honestly when a system is beyond cleaning.
- Check the engineer is Gas Safe registered where any part of the work touches the boiler or gas supply.
- Get the parts and labour split, and any guarantee in writing.
- For anything over a few hundred pounds, get more than one quote on the same described fault — that is the only way the numbers are comparable.
What pushes a heating repair cost up or down
Beyond the fault itself, a handful of factors decide where in the range your quote lands:
- How hard the fault is to find — a visibly dripping valve is quick; a pressure drop from a hidden leak under floors or in walls can take longer to trace than to fix.
- The number of radiators — bleeding, rebalancing and especially power flushing all scale with system size, so a large house costs more than a flat for the same task.
- System age and design — old microbore pipework blocks more easily and is fiddlier to work on than modern larger-bore systems.
- Where you live and when you call — labour in London and the South East typically runs above the national average, and evening, weekend or mid-winter emergency call-outs carry a premium.
- Whether the boiler is involved — if the fault is the boiler itself rather than the system around it, boiler repair pricing applies instead.
If a quote sits well above the ranges here, ask which of these is driving it before you agree to the work.
Central heating repair costs compared
Where this job sits against the other boilers & central heating jobs, on 2026 UK prices. Your own quote depends on size, access and spec.
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