Typical cost in 2025
Most homeowners pay around £2,500 for a standard combi boiler swap, supply and fit
What affects the price?
Boiler type
Combi boilers are the cheapest to install (£1,500–£3,000). System and heat-only boilers cost more due to additional components like hot water cylinders.
Brand and model
Budget brands (Baxi, Ideal) start around £600–£900 for the unit. Mid-range (Worcester Bosch, Vaillant) run £900–£1,500. Premium models can exceed £2,000 for the boiler alone.
Like-for-like vs conversion
Swapping an existing combi for another combi is the cheapest option. Converting from a regular to a combi system requires additional pipework and can add £500–£1,500.
Property size
Larger homes may need a higher output boiler and additional radiators or pipework. A 5-bed house may need a 35kW+ boiler where a 2-bed flat needs only 24kW.
Removal and disposal
Removing and disposing of your old boiler typically adds £100–£300 to the overall cost, depending on its location and condition.
Typical cost breakdown
Estimates are based on UK average rates in 2025. Prices in London and the South East are typically 20–30% higher.
Frequently asked questions
How long does a boiler installation take?
A straightforward like-for-like combi swap typically takes 1 day. More complex installations — such as converting from a regular to a combi system — can take 2–3 days.
Combi vs system boiler — which should I choose?
A combi boiler is ideal for most homes up to 4 bedrooms with 1–2 bathrooms. A system boiler suits larger homes with high hot water demand, as it stores hot water in a cylinder for simultaneous use.
Do I need a Gas Safe registered engineer?
Yes — by law, any gas boiler installation must be carried out by a Gas Safe registered engineer. Always check the register before hiring.
Will my new boiler be covered by warranty?
Most manufacturers offer 5–10 year warranties when installed by a registered engineer and serviced annually. Worcester Bosch offers up to 12 years with a guarantee scheme.
Can I get a boiler on finance?
Many heating engineers offer 0% finance or spread payment options. Government schemes like the Boiler Upgrade Scheme also offer grants of up to £7,500 for heat pumps.