Refurbishment

Boiler replacement cost: new boiler prices

A boiler is one of the first things to check when buying an older home. An ageing or unreliable boiler is a near-certain cost, and replacing it is disruptive and not cheap. This guide sets out what a new boiler costs in the UK, including the unit and the installation.

Last reviewed 5 July 2026

In short

Replacing a boiler in the UK typically costs £2,000 to £4,500 including the boiler and installation. A straightforward combi boiler swap costs around £2,000 to £3,000, while a system or conventional boiler, or a more complex installation, costs £3,000 to £4,500 or more. The price depends on the boiler type and brand, the complexity of the job, and whether pipework, controls or the flue also need changing. Only a Gas Safe registered engineer should fit a gas boiler.

New boiler cost by type

Typical supplied-and-fitted cost for a standard replacement.

Boiler typeBest forTypical fitted cost
Combi boilerSmaller homes, one bathroom, no tank£2,000 to £3,500
System boilerLarger homes with a hot water cylinder£2,500 to £4,000
Conventional (regular) boilerOlder homes with tanks in the loft£2,500 to £4,500
Full swap to combiRemoving tanks and reconfiguring pipework£3,500 to £5,500

What makes up the cost

The boiler itself is often less than half the total.

ElementTypical costNotes
Boiler unit£700 to £2,500Varies by brand, output and warranty
Installation labour£600 to £1,500One to three days depending on complexity
Flue and fittings£100 to £400Longer or repositioned flues cost more
Controls and thermostat£100 to £400Smart controls add convenience and efficiency
Power flush (if needed)£300 to £700Cleans the system to protect the new boiler
Pipework changes£200 to £1,500Relocating or converting boiler type

What affects the price

Why two boiler quotes for the same house can differ by thousands:

  • Boiler type and brand, premium boilers carry longer warranties and higher prices.
  • Changing type, for example moving from a conventional system to a combi.
  • Moving the boiler to a new location, which means new pipework and flue.
  • Whether a power flush or system upgrade is needed to protect the new unit.
  • Adding or upgrading controls such as smart thermostats and zoning.
  • Access and property size, which affect labour time.

How to save on a boiler replacement

Sensible ways to reduce the cost:

  • Match the boiler output to your home rather than over-specifying.
  • Get three quotes from Gas Safe registered engineers and compare like for like.
  • Keep the boiler in the same position to avoid rerouting pipes and flue.
  • Check for manufacturer or energy-efficiency schemes you may qualify for.
  • Service the new boiler annually to protect the warranty and avoid early failure.

Price the boiler before you buy

Our refurbishment planner includes a boiler replacement line so you can add it to your renovation budget and reserve, alongside radiators, rewiring and other systems, before you commit to an older property.

Only use a Gas Safe registered engineer

It is illegal and dangerous to have gas work done by anyone not on the Gas Safe Register. Always check the engineer's ID card and registration before work starts, and keep the paperwork for warranty and safety records.

Common questions

How much does it cost to replace a boiler in the UK?

A boiler replacement typically costs £2,000 to £4,500 including the unit and installation. A simple combi swap is around £2,000 to £3,000, while system, conventional or complex installations cost £3,000 to £4,500 or more.

How much is a new combi boiler fitted?

A new combi boiler supplied and fitted usually costs £2,000 to £3,500. Converting from a conventional system to a combi, which involves removing tanks and reworking pipes, can cost £3,500 to £5,500.

How long does a boiler last?

A well-maintained boiler typically lasts 10 to 15 years. If a property's boiler is near or beyond that age, budget for replacement soon after buying, even if it is currently working.

How long does it take to replace a boiler?

A like-for-like swap usually takes a day. Changing boiler type, moving the boiler, or adding a power flush and new controls can take two to three days.

Do I need a power flush with a new boiler?

Not always, but installers often recommend one on older systems to remove sludge that can damage a new boiler. A power flush costs around £300 to £700 and can be required to keep the warranty valid.

Can I replace a boiler myself?

No. Gas boiler work must be carried out by a Gas Safe registered engineer by law. Fitting a boiler yourself is illegal, dangerous and will invalidate insurance and warranties.

What size boiler do I need?

Boiler output is measured in kW and should match your home's size and number of bathrooms. An oversized boiler wastes energy and money, so ask your engineer to size it to the property rather than guessing.

Sources

Related guides

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