What a boiler replacement actually costs in 2026.
Primary question · What should I budget for a new boiler, and what drives the variance from quote to quote?
A like-for-like combi swap in a typical British 3-bed lands between £1,900 and £3,200 once you allow for the boiler, the magnetic filter, the controls bundle and a competent registered install. The number climbs above that line when the flue route changes, when the gas supply needs upsizing from 15 mm to 22 mm, or when the household takes the opportunity to drop a smart control into the same visit.
Anyone budgeting a real installed cost rather than a brochure number.
Like-for-like combi: £1,900 to £3,200. Relocation or first-time fit: £3,000 to £4,800. System with unvented cylinder: £3,500 to £5,500.
- Honest, segment-specific ranges
- Captures the controls bundle that quietly drives efficiency
- Calls out the relocations that wreck budgets
- Listed buildings, off-grid LPG and commercial domestic installs sit outside these bands
Ask each quoting installer whether the price includes a magnetic filter and a smart control, so the comparison is genuinely like for like.
A boiler quote is rarely just a boiler. The headline difference between two installers usually disappears once you normalise for filters, controls and the unvented-cylinder option. The cheap quote is almost always the one that quietly dropped the bits that matter most over a decade.