How much does a new boiler
cost in London?
An honest breakdown of what a new boiler really costs in London — what moves the price, and what a cheap quote usually leaves out.
A properly installed new boiler in London typically starts from around £2,500 and runs to about £4,500, depending on the boiler chosen and what the job involves. Upgrading to an unvented cylinder such as a Megaflo adds around £3,000 or more on top. Anything advertised dramatically below that range usually has something left out — and this article explains exactly what.
Every property is different, so treat every figure here as a guide, not a quote. I wouldn't give a firm price on any job without seeing the property first.
Why do two quotes for the same job
differ by £1,000?
This is the question homeowners actually ask, and most engineers dodge it online. One company quotes £1,800, another quotes £4,000, and from the outside the two jobs look identical. They usually aren't. Five things move the price.
The boiler and the exact model
Not all Worcesters are the same, and the same is true of every manufacturer. A budget model sits at a very different price to a premium version of the same brand. Warranty length moves it too — a ten-year manufacturer's warranty typically costs more than a five-year one on the same boiler. This is why the model name matters more than the brand name on a quote.
The type of job
A straight swap — the same type of boiler, going back in the same location — is the most straightforward job there is, and the cheapest. Converting from a regular system to a combi, or relocating the boiler, means more pipework and more labour. That cost is real work, not padding.
Your hot water
If you're upgrading to an unvented cylinder — a Megaflo, for instance — for proper mains-pressure hot water, that is a substantially bigger job. Realistically it adds £3,000 or more on top of the boiler work. For a larger home with several bathrooms it transforms the experience. For a smaller property it may be unnecessary.
Whether the job is done properly
This is the invisible one, and it's where cheap quotes are made cheap. Is the installation compliant with building regulations? Is the manufacturer's warranty actually registered? And critically: is the existing system being flushed properly? Installing a new boiler onto a dirty system goes against building regulations, voids your warranty, and damages the boiler you've just paid for.
What's actually included
A proper installation includes a quality magnetic filter; on a combi in London, a scale reducer and a shock arrestor, which are compulsory here; a Boiler Plus compliant thermostat; new valves where needed; removal of the old unit; and everything documented and registered as it should be. A cheap quote often means none of those are included.
What's really behind
a £1,500 boiler quote?
Nine times out of ten, something has been left out. In practice that usually means: no system flush; a budget boiler with a short warranty; old pipework reused; no proper magnetic filter, or a cheap one; no scale reducer and no shock arrestor; no Boiler Plus compliant thermostat. Often the installation isn't properly registered with building control or the manufacturer either, which quietly means the warranty you think you have doesn't exist.
It looks cheaper on the day. Eighteen months later the boiler is struggling, the warranty is worthless, and you're paying again.
Compare what's included, not just the number at the bottom. The cheapest quote and the best value are rarely the same thing.
What a proper boiler quote
should include
A quote you can actually trust shows all of the following in writing:
On the paperwork
The exact boiler make and model going in · The warranty length, and who registers it · A fixed price in writing, so there are no surprises on the day
In the work
The system flush that will be carried out · A quality magnetic filter · For a combi in London: a shock arrestor and a scale reducer · A Boiler Plus compliant thermostat · Any new valves required · Removal and disposal of the old unit
If a quote doesn't include these things — or doesn't explain why they've been left out — ask questions. How someone answers that question tells you a great deal about how they'll work in your home.
"Very professional. Ravinder came out when he said he would and gave me a full written quotation. His pricing was fair, and his communication excellent."
"Did our boiler and Megaflo installation and installed our Powertank pressure booster system. I also got them to come and do my gas safety inspection afterwards. Very professional and I would use them again."
Realistic price guides
by brand
These are starting points from real London installations, not quotes.
Baxi
Installations might start from around £2,500 and run to about £3,000 or more, depending on the model and the warranty length you want. Up to a ten-year manufacturer's warranty is available on these.
Worcester Bosch
Might start from around £2,400 and run to about £4,200 or more, depending on the model and the work involved.
These are realistic, properly installed prices — not the £1,500 figure you see advertised online.
The honest summary
A quality new boiler installation in London might start from around £2,500 and go up to about £4,500, depending on the make and model and what's involved. Anything dramatically below that, look closely at what's been left out rather than assuming you've found a bargain.
Take any price you read online — including these — with a pinch of salt, and get a proper look at your property before you commit to anything.
Prices reviewed August 2026 and re-checked roughly every 90 days.
Quick answers
How much does a new boiler cost in London?
Why do two quotes for the same boiler job differ by £1,000?
What's really behind a £1,500 boiler quote?
What should a proper boiler quote include?
How much does a Megaflo or unvented cylinder add to the cost?
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