Combi Boiler Replacement Cost UK 2026

A like-for-like combi boiler swap in 2026 costs £2,100–£3,200 fitted — typically 1 day's work for a Gas Safe engineer. Worcester Bosch and Vaillant dominate the mid-market.

Quick answer

Typical UK price range: £2,100–£4,500. Typical time: 1–2 days.

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Boiler replacement calculator

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Boiler type Combi (like-for-like) System boiler Heat-only / conventional Combi with move

Region London South East South West Midlands North of England Scotland Wales Northern Ireland

Specification level Basic / standard Mid-range Premium / high-end

Extras

System power flush £350–£700 Magnetic filter £100–£200 Smart thermostat £200–£400 New TRVs (all rads) £250–£600 Flue extension £150–£350

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Estimate only. Prices reflect 2026 UK market data — get quotes from local tradespeople for accurate pricing.

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Budget Under £5,000 £5,000 – £15,000 £15,000 – £30,000 £30,000 – £60,000 £60,000+ Not sure

Timeline As soon as possible 1 – 3 months 3 – 6 months 6+ months Just researching

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Key points

• £2,100–£3,200 fitted (most common range)
• 1 day install (like-for-like)
• 10-year warranty on Worcester Bosch / Vaillant
• Always include power flush + magnetic filter

Cost breakdown

Item	Low	High
Combi boiler (supply)	£900	£2,000
Install labour	£500	£1,000
Power flush	£350	£700
Magnetic filter	£100	£200
Smart thermostat	£200	£400

Cost by UK region

Region	Typical cost
London	£4,455
South East	£4,125
South West	£3,630
Midlands	£3,300
North England	£2,970
Scotland	£3,135
Wales	£2,970

How to save money

• Choose 24–30 kW for a typical 3-bed semi
• Pay for 10-year warranty if available — only £100–£200 extra
• Service annually — keeps warranty valid

How to find a trusted tradesperson

Get at least 3 quotes from vetted UK trade networks:

• Checkatrade
• MyBuilder
• Bark

FAQs

What size combi boiler do I need?

24 kW for a 1-2 bed flat. 30 kW for a 3-bed semi. 35–40 kW for a 4-bed+ with two bathrooms.

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Disclaimer: Prices are guide ranges based on 2026 UK market data. Get quotes from local tradespeople for accurate pricing.