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Combi Boilers

Hot water on demand. No tank needed. Like-for-like swaps usually £2,500–£4,000 fitted (Checkatrade guide)

Instant Hot Water No Tank Required Always Use a Gas Safe Engineer
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What is a Combi Boiler?

A combination (combi) boiler heats water directly from the mains when you turn on a tap - no hot water tank needed. It's a common choice in UK homes because it saves space and heats water on demand.

Modern condensing combi boilers are compact, far more efficient than old non-condensing models, and well suited to small and medium homes with one bathroom. They eliminate the need for cold water tanks in the loft and hot water cylinders in airing cupboards, freeing up valuable space.

Combi Boiler Benefits

Instant Hot Water

No waiting for water to heat - hot water on demand

Space Saving

No tank or cylinder - frees up loft and cupboard space

Installation Cost

Like-for-like combi swaps usually £2,500-£4,000 fitted (Checkatrade guide)

Energy Efficient

Only heats water you use - no heat loss from tank

Simpler Swaps

Replacing a combi with a combi is usually simpler than changing boiler type

Mains-Pressure Hot Water

Flow depends on the model and your mains water pressure

Combi Boiler Costs

£2,500-£4,000
Like-for-like combi replacement, supply and installation
Boiler Only
£650-£3,000
Supply cost
Installation
£1,000-£2,000
Labour and fitting
Changing to a Combi
Around £4,000
Average, from a system or regular boiler

No Grant for Most Boiler Swaps

The Boiler Upgrade Scheme does not fund gas boilers. ECO4 (until 31 December 2026) can sometimes include a broken-boiler replacement where strict rules are met, but a boiler is not guaranteed. UK Energy Partnership is run by Harber Glaves Trading Ltd, not a government body.

Guide prices only
Typical costs, last reviewed September 2026. Source: Checkatrade new boiler cost guide (March 2026). Your quote depends on your home.

Is a Combi Boiler Right for You?

✓ Perfect For:

  • • Small to medium homes
  • • Properties with 1 bathroom
  • • Homes with good mains water pressure and flow
  • • Where space is limited
  • • Flats and apartments

⚠ Consider System Boiler If:

  • • Large home with 2+ bathrooms
  • • Multiple people want hot water at same time
  • • Low mains water pressure
  • • You want powerful shower without electric pump
Learn about system boilers →

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