Updated April 2026
How Much Does a New Boiler Cost?
Replacing your boiler is one of those jobs you can't put off once it starts playing up. Costs vary a lot depending on what you've got now, what you're switching to, and how much pipework needs changing. A straightforward combi-to-combi swap is the simplest job. Converting from a system boiler or moving the boiler to a different room adds time and materials.
What you can expect to pay
| Description | Low | Mid | High |
|---|---|---|---|
| Combi-to-combi swap | £1,500 | £2,000 | £2,500 |
| System boiler replacement | £2,000 | £2,800 | £3,500 |
| Conversion from system to combi | £2,500 | £3,200 | £4,000 |
| Back boiler removal + new combi | £3,000 | £3,800 | £4,500 |
| Boiler relocation (different room) | £3,000 | £3,500 | £5,000 |
All prices include VAT at 20%. Domestic boiler installation is standard-rated.
What affects the price
Boiler type is the biggest factor. A like-for-like combi swap needs minimal pipework changes. Converting from a system or regular boiler to a combi means removing the hot water cylinder and rerouting pipes, which adds a full day or more of labour.
Where the boiler lives matters. If it's staying in the same spot, the installer can usually reuse existing gas and water connections. Moving it means running new pipes, possibly through walls and floors.
London and the South East are typically 15 to 25% more expensive than the Midlands or North. A job that costs £2,000 in Manchester might be £2,400 in London.
The boiler brand affects the upfront cost and the warranty length. Worcester Bosch and Vaillant tend to sit at the higher end. Ideal, Baxi, and Glow-worm offer solid mid-range options. A boiler with a 10-year warranty at £200 more often makes better sense than chasing the cheapest unit.
Older properties sometimes need a system flush (powerflush) to clean out sludge before fitting a new boiler. This typically costs £300 to £500 on top.
How to keep costs down
- 1
Get at least three written quotes and make sure they specify the boiler model, not just "a new combi boiler." You want to compare like for like.
- 2
Summer and early autumn are quieter for heating engineers. You'll often get better availability and sometimes lower prices than the winter rush.
- 3
Ask whether the quote includes the Building Regulations notification. This is a legal requirement for gas work. Most Gas Safe engineers include it, but check.
- 4
If your boiler is over 15 years old but still working, get a service first. Sometimes a repair is all you need. But if it's breaking down regularly, replacement usually works out cheaper over a couple of years.
- 5
Check for manufacturer cashback offers. Boiler brands regularly run promotions, especially in the quieter months.
Frequently asked questions
Common signs include frequent breakdowns, rising energy bills, uneven heating, and the boiler being over 15 years old. If your engineer says parts are no longer available, it's time. A boiler that costs £300+ a year in repairs is usually cheaper to replace.
A simple combi-to-combi swap usually takes one day. Converting from a system boiler or relocating the boiler can take two to three days. Your installer should give you a timeline in the quote.
For most homes with one bathroom, a combi is the best choice because it heats water on demand and doesn't need a cylinder. Larger homes with two or more bathrooms often benefit from a system boiler with a cylinder, as it can supply multiple outlets at once.
Not usually. If your radiators are in good condition and heat up evenly, they'll work fine with a new boiler. If some rooms are cold or radiators have pinhole leaks, it's worth replacing those while the system is being drained.
Generally yes. The difference between a 5-year and 10-year warranty is often £200 to £400 upfront, but a single boiler repair can cost £150 to £300. A longer warranty protects against the most expensive early failures.
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