What a new boiler actually costs in 2026 — and what changes the price
Ask three firms for a price and you can get three very different numbers for the same house. Usually the boiler is the smallest part of the difference. Here is what you are actually paying for.
The short answer
For a straight swap — same type of boiler, same place on the wall, no surprises — most homes land between £1,800 and £2,800 fitted. Move the boiler, change the system type, or convert from a hot water tank to a combi, and you are into the £3,000 to £4,500 range.
Those are fitted prices including VAT, the appliance, labour, commissioning, notification and taking the old one away. If a quote is materially below the bottom of that range, something has been left out of it — and it is worth finding out what before you sign.
Why the range is so wide
People assume the boiler is the expensive bit. On a typical job the appliance is somewhere between a third and a half of the total, and the gap between a decent mid-range boiler and a premium one is often only a few hundred pounds. Everything else is labour and materials — and that is where quotes diverge.
Two firms quoting the same house differently are usually not disagreeing about the boiler. They are disagreeing about how much work the installation needs.
What actually moves the price
Whether the boiler moves
Leaving it where it is keeps the gas run, the flue hole and the pipework largely as they are. Moving it to a different wall — or from the kitchen to the loft — means new gas, new flue, new condensate and making good afterwards. This is the single biggest swing on most jobs.
Combi, system or heat-only
Like for like is cheapest. Converting from a tank-fed system to a combi means removing the cylinder and header tanks, capping off, upgrading the incoming gas and mains, and reworking the airing cupboard. It is a bigger job than it sounds, and it is why conversions sit at the top of the range.
Gas pipe size
Older houses often have a 15mm gas run that will not feed a modern boiler at full rate. Upgrading it to 22mm can mean lifting floorboards or running pipe round the outside. It is not optional — a boiler starved of gas will not perform, and it is the sort of thing a cheap quote quietly assumes away.
The state of the existing system
Years of sludge in old radiators will find their way into a new boiler's heat exchanger. A proper chemical flush or, in bad cases, a powerflush protects the appliance and is usually a condition of the manufacturer's warranty. So is fitting a magnetic filter.
Flue route and access
A flue straight out through the wall behind the boiler is simple. A vertical flue through a roof, a long horizontal run through a cupboard, or anything needing scaffolding adds materials and time. Flats and terraces with awkward flue positions cost more for good reason.
Boiler size and brand
Genuinely the smallest lever. Sizing should come from your radiators and hot water demand, not from a guess — an oversized boiler cycles on and off, wears faster and costs more to run. Brand affects warranty length more than day-to-day performance.
What should be in every quote
A quote that only says "supply and fit boiler" is not a quote, it is an opening position. Ours lists each of these, and so should anyone else's:
- The exact boiler — make, model and output in kW
- Warranty length, and what you have to do to keep it valid
- Whether a system flush is included, and what kind
- Magnetic filter, and whether it is included or extra
- New controls or thermostat, if any
- Gas Safe notification and building regulations certificate
- Removal of the old boiler and all packaging
- What is explicitly not included — making good decoration, lifting fitted flooring, electrical work beyond the appliance
Where you can safely save — and where you shouldn't
Sensible savings: keeping the boiler in its existing position, staying with the same system type, choosing a solid mid-range appliance over a premium badge, and booking outside the autumn rush when everyone wants a boiler at once.
False economies: skipping the flush, skipping the filter, accepting a boiler sized by eye, or letting someone talk you out of a written fixed price. Each of those saves a couple of hundred pounds now and can cost considerably more later — often by voiding the warranty that was the reason you paid for that boiler in the first place.
Why the cheapest quote often grows
The pattern is consistent. A low number wins the job, then the gas pipe turns out to need upgrading, the flush was not included, and the filter is extra. You end up around the same total as the honest quote, but with less goodwill and no fixed price to point at. A slightly higher quote that lists everything is usually the cheaper job.
What a fixed price should mean
Ours means the number does not move, provided what you told us was accurate and nothing was hidden that we could not reasonably have seen. If we open up a floor and find something genuinely unforeseen, we stop, show you, and price it before touching it. You are never billed for something you have not agreed to.
That is the whole trick to boiler pricing. Not the cheapest number — the number that does not change.