If you’re trying to work out what a new combi boiler will cost — fully installed — you’re in the right place. Whether your boiler has broken down or you’re planning ahead, this guide breaks down the real cost of combi boiler installation in 2026, so you know exactly what to budget and what to look out for.
How Much Does Combi Boiler Installation Cost?
The average cost of combi boiler installation in the UK is £1,800 to £3,200, including the boiler unit and all labour. Here’s how the price typically breaks down:
| What’s included | Typical cost |
|---|---|
| Combi boiler unit (mid-range brand) | £700 – £1,200 |
| Installation labour (1–2 days) | £500 – £800 |
| Flue, fittings, and materials | £150 – £300 |
| Magnetic filter (recommended) | £80 – £150 |
| Gas Safe certificate | Included |
| Total (fully installed) | £1,800 – £3,200 |
Premium brands like Worcester Bosch push the upper end of that range. Budget brands (Ideal, Baxi) bring it down.
What Affects the Cost of a New Boiler Installation?
1. The boiler brand
Worcester Bosch and Vaillant sit at the top on price — but they also carry the best reliability records and up to 12-year warranties. Baxi and Ideal are solid mid-range options.
2. Boiler size (kW output)
A standard 3-bedroom home needs a 24–28kW combi. Larger homes with multiple bathrooms need 32–40kW.
3. Like-for-like vs. conversion
Replacing a combi with a combi (same location, same pipework) is the cheapest install. Converting from a heat-only or system boiler adds cost for extra pipework, cylinder removal, and labour time.
4. Flue requirements
A standard horizontal flue is included in most quotes. Vertical flues or long runs add £100–£400.
5. Additional work
- Power flush (recommended on older systems): £300–£500
- Scale reducer (hard water areas): £80–£150
- New thermostatic radiator valves: £15–£40 per radiator
- Magnetic filter: £80–£150
Combi Boiler Installation Cost by Brand
| Brand | Unit cost (approx.) | Warranty | Reliability |
|---|---|---|---|
| Worcester Bosch | £900 – £1,400 | Up to 12 years | Excellent |
| Vaillant | £850 – £1,300 | Up to 10 years | Excellent |
| Baxi | £700 – £1,000 | Up to 10 years | Good |
| Ideal | £600 – £900 | Up to 10 years | Good |
| Intergas | £750 – £1,100 | Up to 10 years | Very good |
These are unit-only prices. Add £600–£900 for installation labour in most cases.
Our recommendation: Worcester Bosch or Vaillant for most homeowners. For budget-conscious buyers, Baxi is a reliable step down.
New Boiler Installed Cost vs. Supply-Only
You may see boilers advertised for £500–£800 supply-only. This is the boiler unit alone — it doesn’t include fitting, a flue, pipework changes, or the Gas Safe certificate.
What a fully-installed price should include:
- The boiler unit
- Flue and fittings
- Removal and disposal of your old boiler
- All installation labour
- Commissioning and testing
- Gas Safe Certificate
- Manufacturer warranty registration
Need a free quote for your Kent home? Our Gas Safe engineers cover Canterbury, Dover, Folkestone, Deal, and surrounding areas.
→ Get a Free Combi Boiler Quote
Is It Worth Paying More for a Better Boiler?
In most cases, yes. A £700 budget boiler that breaks down in year 3 and needs £400 in repairs will end up costing more than a £1,200 Worcester with a 12-year warranty. Over a 10-year period, the total cost of ownership often favours the premium brand.
Can I Get a Free Combi Boiler?
Some homeowners qualify for a free or heavily subsidised boiler through the government’s ECO4 scheme. To qualify, you typically need to:
- Be receiving means-tested benefits (Universal Credit, Pension Credit, etc.)
- Have a home with an EPC rating of D, E, F, or G
- Own your home or have landlord consent (private renters may also qualify)
How Long Does Combi Boiler Installation Take?
A standard like-for-like combi boiler replacement takes 1–2 days. You’ll be without heating and hot water while work is underway, but your engineer should have everything back on by end of day 1 in most cases.
Frequently Asked Questions
How much does combi boiler installation cost in 2026?
The average cost of a fully installed combi boiler in the UK is £1,800–£3,200, depending on the brand, boiler size, and complexity of the installation. Like-for-like replacements in Kent are typically at the lower end of this range.
What is included in the cost of a new boiler installation?
A proper fully-installed quote covers the boiler unit, flue and fittings, removal of your old boiler, all labour, commissioning, Gas Safe certificate, and warranty registration.
Is a combi boiler cheaper to install than a system boiler?
Usually yes, if you’re already on a combi. Converting from a heat-only system adds cost for removing the cylinder and tank.
How do I get the cheapest combi boiler installation?
Get at least 3 quotes from Gas Safe registered engineers. Avoid peak winter demand if possible. Opt for a like-for-like replacement.
Does combi boiler installation include a Gas Safe certificate?
Yes — by law, any gas work must be carried out by a Gas Safe registered engineer and a certificate must be issued.
Ready to Get a Quote?
We cover Canterbury, Dover, Folkestone, Deal, Maidstone, Ashford, and the wider Kent area. Quotes are free, no-obligation, and we’ll always give you a fixed price.