Cost Guide
Boiler Repair Cost In London: What To Expect
Reviewed by our Gas Safe registered engineers · Last updated 21 July 2026
Repair costs vary hugely depending on what’s actually wrong, which is why generic ‘boiler repair cost’ figures online are often not that useful. Here’s a realistic breakdown by common fault.
Quick Price Summary
Most common boiler repairs in London run £90–£350, with major component failures (like a heat exchanger) running higher. A callout / diagnostic fee usually applies separately.
Want a firm figure? Call 020 7108 6322 and we’ll talk it through before any visit.
Costs
Typical repair costs by fault
Figures are general guidance; the exact cost depends on your specific boiler model and part availability.
What affects the price
- Which component has failed
- Your specific boiler model
- Part availability
- Whether the model is discontinued
What’s included
- Gas Safe registered engineer
- Parts and labour quoted upfront
- Workmanship and parts guaranteed
- Honest repair-or-replace advice
Repair vs Replacement
When repair stops making sense
A rough rule of thumb: if a single repair quote approaches a third or more of a new boiler’s cost, or if your boiler has needed multiple separate repairs within the past year or two, replacement often becomes the better long-term value — particularly for boilers over ten to twelve years old.
A newer boiler under warranty is almost always worth repairing rather than replacing. We’ll always give you an honest view of which makes more sense for your specific situation rather than defaulting to whichever’s more profitable for us.
Usually worth repairing
- The boiler is under ten years old
- It’s still within manufacturer warranty
- This is the first fault in recent years
- The quote is well under a third of replacement cost
- Parts are current and readily available
- It has been serviced regularly
Replacement often makes more sense
- The boiler is past ten to twelve years old
- It has needed several separate repairs recently
- The quote approaches a third or more of a new boiler
- The model is discontinued and parts are slow to source
- A major component has failed — heat exchanger, for instance
- Efficiency has visibly dropped and bills have risen
Not sure whether to repair or replace?
Get an honest assessment from a Gas Safe registered engineer — no upsell.
FAQs
Repair costs — your questions answered
Is the diagnostic fee separate from the actual repair cost, or included?
Typically separate — the diagnostic fee covers identifying the fault, and the repair cost (parts and labour) is quoted once the diagnosis is confirmed, so you know the full picture before agreeing to proceed.
Will I be charged the diagnostic fee if I decide not to proceed with the repair?
The diagnostic fee covers the engineer’s time and expertise in identifying the fault, so it typically applies regardless of whether you go ahead with the repair, though this is always made clear before the visit. If you do proceed with a repair on the same visit, the diagnostic fee is often included within the overall repair cost rather than charged separately on top.
Does part availability affect how quickly a repair can be completed?
Yes, common parts are usually held in stock or available within a day or two, but less common or older boiler models can occasionally mean a longer wait for the specific part needed.
Are older, discontinued boiler models more expensive to repair due to parts scarcity?
Sometimes, yes. Parts for boilers no longer in production can take longer to source and occasionally cost more than parts for current models still in wide circulation. If your boiler is both old and increasingly hard to source parts for, this is often one of the practical factors that tips the repair-versus-replace decision toward replacement.
Would a repair on an out-of-warranty boiler come with any guarantee of its own?
Yes, we guarantee our workmanship and parts fitted, giving you assurance on the specific repair carried out, separate from any remaining manufacturer warranty on the boiler itself.
Is it ever worth repairing a boiler myself to save on labour costs?
No — boiler repairs involve gas safety and must legally be carried out by a Gas Safe registered engineer, so this isn’t a DIY-appropriate job regardless of confidence level.
How do I know if a quoted repair price is reasonable?
Ask for a breakdown of parts versus labour, and don’t hesitate to get a second opinion for a significant repair — a reputable engineer won’t mind you doing your due diligence.
Does regular servicing reduce how often expensive repairs are needed?
Yes, generally — catching small issues (like early sludge build-up or a marginal component) during an annual service tends to prevent them developing into larger, more expensive failures.
Related cost guides
We repair all major boiler brands across Southwark, Lewisham and Greenwich, and the rest of our coverage area.
Need a straight answer on repair vs replace?
We’ll give you an honest assessment, no upsell.
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