How Much Are Combi Boiler Prices in 2026? (UK)
A new combi boiler costs £600–£1,500 for the unit and £2,000–£3,500 fully fitted in the UK in 2026. The price depends on the brand, the output in kW, and how much pipework, flushing and controls the installation needs. Here is the full breakdown by brand and size, and how to compare installer quotes.
Combi boiler price breakdown 2026
As a guide for 2026, the boiler unit alone costs around £600–£1,500 depending on brand and output, and a straight swap fitted lands at £1,800–£2,800. A full installation with new pipework, a system flush and smart controls typically runs £2,500–£3,500, and moving the boiler to a new location more again. Budget brands sit at the lower end and premium brands with long warranties at the top.
Combi boiler prices by brand
As a rough 2026 guide for the unit: budget brands such as Baxi or Ideal from around £600–£1,000, mid-range such as Vaillant or Worcester Bosch entry models £900–£1,300, and premium Worcester Bosch or Viessmann flagship units £1,200–£1,700. A longer manufacturer warranty, higher efficiency and better hot-water flow rate are what you pay more for. Fitting is quoted on top.
Combi boiler prices by size
Output is sized on hot-water demand, not floor area: how many bathrooms might run at once matters more than how many bedrooms there are. Undersizing shows up as weak flow at the shower; oversizing costs more to buy without heating the house any faster.
Above roughly five bedrooms or three bathrooms a combi is usually the wrong tool, and a system boiler with a cylinder gets quoted instead — see the full boiler replacement cost guide for those.
What drives the fitted price
Beyond the unit, the installed price is driven by the output you need for the number of bathrooms, whether it is a like-for-like swap or a move, the amount of new pipework and a system flush, adding a filter and smart controls, and any flue or condensate changes. A conversion from a conventional or system boiler to a combi costs more because tanks are removed and pipework reworked.
How to budget and compare quotes
1. Size the boiler
Match the output in kW to the number of bathrooms and radiators so hot-water flow is right — too big wastes money.
2. Choose the brand and warranty
Weigh upfront price against efficiency and warranty length, which affect long-term running and repair costs.
3. Confirm what the install includes
Check for a system flush, filter, smart control and any pipework or flue changes so quotes are comparable.
4. Get three like-for-like quotes
Compare Gas Safe installers on the same boiler and scope so you judge value, not just headline price.
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