How much does a boiler replacement cost in the UK?
A boiler replacement is one of the most common and most expensive household jobs in the UK. Here is a detailed breakdown of what it costs in 2025–2026 — and what you are paying for.
Typical boiler replacement costs (2025–2026)
| Boiler type | Unit cost | Installed (incl. labour + parts) |
|---|---|---|
| Combi boiler (24–30kW), like-for-like swap | £700 – £1,400 | £1,800 – £3,000 |
| Combi boiler, system change (e.g. from a tank system) | £700 – £1,400 | £2,500 – £4,500 |
| System boiler + unvented cylinder | £900 – £1,800 | £3,000 – £5,500 |
| Regular (heat-only) boiler | £700 – £1,300 | £2,000 – £3,800 |
| Powerflush (central heating system clean) | £300 – £600 | |
| Boiler service (annual) | £70 – £120 | |
What is included in the installed price?
A full boiler replacement typically includes:
- Removing and disposing of the old unit
- Supply and installation of the new boiler
- A magnetic system filter, fitted to protect the new boiler from debris in old pipework (if not already present)
- Manufacturer's benchmark commissioning checklist, completed and signed
- Building Regulations notification (via the installer's Gas Safe or other Competent Person Scheme registration, or a separate notification to building control)
- Manufacturer warranty registration
Items that may be quoted separately: a full powerflush of the existing system, replacement of aged pipework or radiators, a smart thermostat, or additional works if the flue route changes.
Why Gas Safe registration matters
It is a legal requirement in Great Britain that anyone working on a gas boiler, gas appliance, or gas pipework is on the Gas Safe Register. Ask to see the engineer's Gas Safe ID card and check their registration and licence number on the Gas Safe website before work starts — never use anyone who isn't registered. Using an unregistered installer can also invalidate your home insurance if something goes wrong. TruePro verifies Gas Safe registration and shows a badge on the engineer's quotes and profile once confirmed.
Which type of boiler should you choose?
- Combi boiler: the most common choice in the UK — no hot water cylinder or cold water tank needed, instant hot water, and the most compact option. Best suited to smaller homes or flats with one bathroom and moderate hot water demand.
- System boiler: heats water into a hot water cylinder, so it can supply multiple bathrooms simultaneously without a drop in pressure. A sensible choice for larger homes with higher demand.
- Regular (heat-only) boiler: the traditional setup, with a cold water tank in the loft feeding a hot water cylinder. Mostly used when replacing an existing regular-boiler system rather than in new installations.
- Heat pump alternative: rather than replacing like-for-like, some homeowners consider an air source heat pump instead of a gas boiler. The government's Boiler Upgrade Scheme (England and Wales) has offered a grant toward the cost — funding levels and eligibility are reviewed periodically, so check current terms with your installer or on GOV.UK before assuming a figure.
Tips for getting a fair price
- Get quotes that specify the boiler brand and model — not just "a combi boiler." Worcester Bosch, Vaillant, Ideal, and Baxi are common brands in the UK; warranty length and installer accreditation both affect what cover you actually get.
- Confirm the manufacturer warranty length included — this often depends on using an accredited installer (e.g. a Worcester Bosch Accredited Installer), and can range from 2 years to 10+ years.
- Ask whether a magnetic filter and Building Regulations notification are included. If they are not, ask why — the work is not properly compliant without notification.
- Check whether your home insurance or the manufacturer's warranty requires an annual service to stay valid, and budget for it.
- Avoid paying the full amount upfront. TruePro's payment protection holds your payment securely until you've confirmed the installation is complete and any required certificate has been issued.