How much does a boiler replacement really cost?
Costs vary significantly based on your situation. These ranges give you a realistic starting point before you contact installers.
Typical price ranges
These are guide prices for supply and installation in the UK. Your actual quote will depend on the factors below.
Combi boiler replacement
Like-for-like swap in the same location, standard flue, no major pipework changes
System boiler replacement
Including cylinder replacement if needed, standard installation
Regular boiler replacement
Full system with cylinder and tanks, standard installation
Complex installation
Boiler relocation, system-type change, significant pipework or scaffolding required
Note: prices vary by region, with London and the South East typically 10–20% higher. These ranges are indicative only.
What drives the cost up
- Boiler type and output
- A larger or more powerful boiler costs more. The right size depends on your home's heating demand, not on buying the biggest available.
- Installation complexity
- Moving the boiler to a different location, changing system type (for example regular to combi), or accessing difficult spaces all add labour time and cost.
- Flue requirements
- Standard horizontal flues through external walls are cheapest. Vertical flues through roofs, long flue runs, or plume management kits add £100–£400.
- Pipework modifications
- If your existing pipework needs significant changes, rerouting, or upgrades to accommodate the new boiler, costs increase accordingly.
- Controls and accessories
- Smart thermostats, additional TRVs, magnetic filters, and scale reducers all add to the total. Some are worthwhile, others are optional extras.
Hidden extras to watch for
Make sure your quote clearly includes or excludes these items: (all prices are approximate)
- Chemical flush / powerflush, £300–£500 if needed, but not always necessary.
- Gas pipe upgrade, £150–£300 if your existing pipe is undersized.
- Scaffolding, £200–£500 if the boiler is at height.
- Building regulations compliance, usually included, but check.
- Extended warranty, often charged separately, £100–£300+ per year.
What should be included in a standard quote
- The boiler unit itself
- Installation labour
- Standard flue and fittings
- Basic controls (programmer / thermostat if being replaced)
- Removal and disposal of the old boiler
- Gas Safe registration and building control notification
- The manufacturer's standard warranty (typically 2–5 years)
What to do next
Once you have a realistic budget in mind, learn how to compare quotes properly and spot the red flags that suggest a quote isn't what it seems.