Boiler Replacement London
Search "boiler replacement cost London" and you'll find guide after guide quoting £1,800 to £10,000 without telling you what you'd actually pay. We're not a guide — we're the installer, and here are our real fixed prices.
How Much Does Boiler Replacement Cost in London?
Boiler replacement in London starts from £1,050 for a straightforward like-for-like combi swap, rising to £3,500 for converting to a system boiler, and £4,000 for replacing an existing system boiler and cylinder. Most online cost guides quote ranges like £1,800 to £10,000 — technically accurate, practically useless, since they're averaging across dozens of unrelated companies and job types. Our prices are fixed per job type, confirmed with a £100 assessment visit before you commit to anything.
Which Type of Boiler Replacement Do You Need?
This is the question every generic cost guide skips past. The type of replacement, not just the boiler brand, is what actually determines your price.
Like-for-Like Combi Replacement
New combi boiler in the exact same spot as your old one, connected to existing pipework. No rerouting, no cylinder. The fastest and cheapest option.
See like-for-like pricing →Combi to System Conversion
Switching from a combi to a system boiler with a cylinder for the first time, to fix weak pressure when multiple bathrooms run at once.
See conversion pricing →New System Boiler Installation
Replacing an existing system boiler and ageing cylinder together with modern equivalents. Pipework already exists, so it's faster than a conversion.
See new system pricing →Combi Boiler Packages
Our full range of 20 combi boiler packages across every major brand, with exact pricing per model and output.
Browse all packages →Not sure which one describes your home? Send us a photo of your current boiler on WhatsApp and we'll tell you honestly, even if it's the cheaper option.
Repair or Replace? How to Decide
- 1
It's over 10-12 years old
Beyond this age, parts availability drops and efficiency losses often outweigh repair costs.
- 2
You've had more than two repairs this year
Repeated call-outs for different faults usually signal general failure, not one fixable issue.
- 3
A repair quote is close to half a new boiler's cost
At that point, a fresh warranty on a new unit usually makes more financial sense.
- 4
It's a single, specific fault
No heating, no hot water, an error code, or low pressure on an otherwise young boiler is usually worth repairing first — see our repair and servicing page.
What Affects Your Boiler Replacement Price
⚠ A cost most guides don't mention: gas pipe upgrades
Modern high-efficiency combi boilers need a higher gas flow rate than older models. If your property's internal gas pipe between the meter and the boiler is too narrow, which is particularly common in pre-1970s London properties and homes with long pipe runs, it needs upgrading to supply enough gas safely. We check this during your free assessment so it's never a surprise added on the day — many installers only discover this once work has already started.
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Replacement type
Like-for-like, conversion, or new system — the single biggest price factor.
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Boiler brand & output
Larger kW output and premium brands like Vaillant or Worcester Bosch cost more than budget alternatives.
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Pipework & flue condition
Older or non-compliant existing pipework sometimes needs upgrading alongside the boiler itself.
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Access & property type
Mews houses, listed buildings, and flats with restricted access can affect labour time.
Common Questions
What's the cheapest type of boiler replacement?
A like-for-like combi replacement, where the new boiler goes in the exact same spot as the old one with no new pipework, is the cheapest option, starting from £1,050.
How do I know if I need a repair or a full replacement?
If your boiler is over 10 to 12 years old, has needed more than two repairs in the past year, or a single repair quote is close to half the cost of a new boiler, replacement is usually the better financial decision.
Does boiler replacement always include a new thermostat?
Yes, with us. A digital thermostat is included as standard, and a smart thermostat is included free when bundled with any boiler package.
How long does a boiler replacement take in London?
A like-for-like combi replacement takes 4 to 6 hours, usually completed in a single day. A system boiler conversion takes 1 to 2 days. A new system boiler and cylinder replacement typically takes 1 day.
What certificate do I get after boiler replacement?
A Gas Safe certificate confirming the work meets current safety standards, plus manufacturer warranty registration, both provided the day the work is completed.
Get Your Real Fixed Price Today
Tell us your current boiler type and postcode on WhatsApp and we'll confirm exactly which replacement category you need and the price — no guesswork range.
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