A new boiler typically costs £1,500–£4,500 fully installed in the UK, depending on the type of boiler and the complexity of the installation. Combi boilers sit at the lower end; system and regular boilers with a cylinder cost more due to extra parts and labour.
Average Boiler Installation Costs
| Boiler Type | Unit Cost | Installation Cost | Total (Fitted) |
|---|---|---|---|
| Combi boiler | £600–£2,000 | £500–£1,500 | £1,100–£3,500 |
| System boiler | £700–£2,200 | £800–£1,800 | £1,500–£4,000 |
| Regular (conventional) boiler | £700–£2,200 | £1,000–£2,000 | £1,700–£4,200 |
| Like-for-like replacement | — | — | £1,500–£2,500 |
| Switching boiler type (e.g. regular to combi) | — | — | £3,000–£4,500+ |
Costs rise significantly if pipework needs rerouting, if you're moving the boiler's location, or if your home needs a new flue run.
What Affects the Price?
Boiler type and output size. Larger homes with more bathrooms typically need a higher-output boiler, which costs more upfront.
Like-for-like vs a full system change. Swapping an old combi for a new combi in the same spot is the cheapest and fastest job. Switching from a regular boiler and cylinder to a combi (or vice versa) involves removing the old cylinder, altering pipework, and sometimes rerouting the flue — this can add £1,000–£2,000 to the job.
Brand and warranty length. Boilers with longer manufacturer warranties (10–12 years) cost more upfront but can save money over the boiler's lifetime.
Access and location. A straightforward loft or cupboard swap is quicker than a boiler tucked in an awkward space or one requiring scaffolding access.
Do I Need a Gas Safe Registered Engineer?
Yes — by law, anyone installing, repairing, or servicing a gas boiler in the UK must be on the Gas Safe Register. It's a criminal offence for anyone else to carry out this work. Always ask to see a Gas Safe ID card before work begins, and check the engineer's registration number on the Gas Safe Register website — it only takes a minute and confirms they're legally allowed to do the job.
When Is the Best Time to Replace a Boiler?
Ironically, the worst time to discover you need a new boiler is the depths of winter, when demand is highest and engineers are booked out weeks in advance. If your current boiler is 10+ years old, getting a quote in late summer or early autumn — before the cold snap — means more availability and often better pricing, since engineers aren't run off their feet.
Getting an Accurate Quote
A proper boiler quote should specify:
- The exact make and model being installed
- Whether it includes a new thermostat and any required upgrades (e.g. flue, filter, magnetic system filter)
- Manufacturer warranty length
- Whether removal and disposal of your old boiler is included
- Building Regulations notification (all boiler installations must be notified — a registered installer handles this automatically)
Compare Boiler Installation Quotes
Boiler costs vary considerably between installers for the same job, so it's worth comparing more than one quote before booking. Post your job for free on Compare My Builder and get matched with verified, Gas Safe registered heating engineers in your area.
Or browse verified heating engineers directly: Find Heating Engineers Near You →