Almost every published "new boiler price" is really two numbers glued together: the appliance and the work needed to make that appliance behave properly in your particular house. The appliance part is public — manufacturers publish list prices and merchants discount from them. The second part is where quotes for the same boiler end up hundreds of pounds apart, and it is almost never because one installer is greedy and another is generous.
Across the UK market in 2026, a straight combi-for-combi swap in an easy position commonly lands somewhere in the £2,000–£3,000 region fitted, while conversions, relocations and system upgrades run higher because the labour and materials list is longer. Those are market ranges quoted for context, not our figures — every home gets its own written quote after someone has actually looked at the pipework.
The five cost blocks inside any boiler quote
Ask any installer to split their number this way and comparison gets much easier.
| Cost block | What it covers | What moves it up or down |
|---|---|---|
| Appliance | The boiler itself, plus its own flue kit | Output, brand tier, whether it is a combi, system or heat-only unit |
| Installation labour | Removal, hanging, connecting, commissioning, paperwork | One day versus two or three; loft or airing-cupboard access |
| Ancillaries | Magnetic filter, scale reducer, valves, brackets, condensate route | Hard-water areas, awkward condensate runs, old imperial pipework |
| System work | Flush or clean, new radiator valves, pipe upgrades, gas run upsizing | Age and condition of the existing heating circuit |
| Controls | Programmer, room thermostat or smart controls, wiring centre | Whether existing controls are compatible with the new appliance |
A quote that shows only one figure is not necessarily wrong — but it hides which of these five it has and has not included.
Why the gas supply can change the price on its own
Modern combis draw a lot of gas when they fire for hot water. If the existing supply pipe is undersized — very common in houses where the meter sits at the front and the boiler at the back — the pressure drop across it will be outside permitted limits once the new appliance is running flat out. That is not a preference; it is a measurement taken at commissioning, and it either passes or it does not.
Upsizing that run may mean lifting floorboards, boxing along a skirting, or routing outside in coated pipe. It is one of the biggest single reasons a quote comes in higher than the neighbour's did, and it is also the reason some cheap installations end up with a boiler that never delivers the hot water flow the brochure promised.
Costs people forget to budget for
None of these are optional extras invented to inflate a bill — each one exists because of the building.
- Condensate disposal to an internal drain where an external pipe would freeze
- Making good after removing a floor-standing or back boiler, including hearth and flue work
- A magnetic system filter, which most manufacturers require for their warranty terms
- Electrical work where the old boiler was on a fused spur that no longer suits the new controls
- Asbestos surveying or removal where old flue seals or artex are disturbed
- Scaffolding or a tower where a flue terminates high up or over a conservatory roof
Cheap, mid and premium: what the extra money buys
At the budget end you are usually buying a shorter warranty, a smaller heat exchanger and a parts network that is less widely stocked. That can be perfectly sensible in a flat you plan to sell, or where the heating load is modest.
In the middle you get longer warranties, better modulation — the ability to run gently at low output rather than short-cycling — and parts that most engineers carry. Premium units add flow rate, quieter operation, better weather-compensation support and warranties that can extend into double figures when installed by an accredited installer and serviced annually.
The important thing is that a well-installed mid-range boiler will nearly always outperform a premium boiler fitted badly onto a dirty system. Spend on the installation before you spend on the badge.
Get a written boiler quote for your own house
We survey the gas run, the flue route and the existing system before quoting, so the number you get reflects the work your property actually needs.
A boiler quote is really a description of your house, written in money. When you can see the five blocks separately, you can tell the difference between an expensive quote and a thorough one — and those are not the same thing.