How much does a boiler replacement cost in London in 2026?

A like-for-like combi swap in a typical SW or KT postcode home in 2026 costs between £1,899 and £2,650 fitted. That's for a 24–30kW Worcester Bosch 4000 or Vaillant ecoTEC Plus, with a 10–12 year warranty and a magnetic system filter.

What pushes the price up?

• Moving the boiler to a different room — add £400–£800 for new pipework and a flue.
• System or regular boiler (with a hot water cylinder) — usually £2,400–£3,400.
• Older properties needing a system powerflush — add £495.
• A larger boiler (35kW+) for homes with 3+ bathrooms — add £200–£400.

What keeps it down?

• Staying with the existing brand and position.
• Swapping during summer (most installers discount April–August).
• Sourcing your own boiler — we'll fit a customer-supplied unit, though warranty admin sits with you.

We send a fixed written quote within 24 hours of a free home survey across South West London, Kingston, Sutton and Twickenham.