How much does a new boiler cost in the UK?
A new boiler quote depends on the equipment and work included. Compare itemised installation quotes separately from estimated fuel savings using the existing boiler calculator.
Prepared from existing project material on 24 October 2026. Editorial review: not yet recorded. Live figures use the current record; existing evidence dates are unchanged.
See also: Gas boiler running cost calculator · ECO4 grants guidance · Heat pump running cost calculator · Home heating guidance
Separate installation cost from running cost
The amount paid to supply and install a boiler is different from the fuel used after installation. A lower upfront quote does not necessarily lead to lower running costs, and an efficient boiler does not guarantee that replacement pays back quickly. Start by identifying what work is actually needed and what the existing system can still do.
PowerGuardian’s boiler calculator already includes illustrative supply, labour, extras and efficiency assumptions. Those are planning inputs, not a verified current market price range for your home. This guide does not turn the older illustrative figures into current installation benchmarks. Use an itemised written installer quote for the upfront total and the existing model for a clearly labelled comparison.
What should be included in an installation quote?
Check the boiler model, controls, any cylinder work, flue arrangement, disposal, commissioning, paperwork and warranty conditions. Ask whether the price assumes a like-for-like replacement in the same position. Moving the boiler or changing the system type can involve work that is absent from a basic swap quote.
Ask which system cleaning, filters or pipework changes are included and which are optional. Access, making good and electrical work can affect the scope. Do not compare one quote containing those items with another that excludes them as though the products were identical. Any uncertain work should be explained in writing, including how additional costs would be approved, rather than hidden behind a broad “from” price.
Size and system type affect the decision
A combi, system or regular boiler serves hot water differently and may interact with existing cylinders or storage. The best choice depends on household demand and the heating design, not simply the largest available output. An installer should assess the property and system rather than relying on a bedroom count alone.
The calculator’s sizing recommendation is an illustration within its model, not a substitute for design work or an instruction to purchase that output. Ask why the proposed model and size are suitable, what controls will be fitted and how the system will be commissioned. Keep the installation design separate from the calculation of annual fuel cost. A more powerful rating does not automatically mean higher annual energy use.
How a more efficient boiler can use less fuel
For the same useful heat demand, divide that demand by the old seasonal efficiency to estimate old fuel input, then by the new efficiency to estimate the replacement input. Subtract the two fuel amounts and multiply by the appropriate unit price. Efficiencies must be expressed as fractions when dividing; keep the demand and tariff on a consistent basis.
The existing calculator uses age and tier efficiency assumptions from its configuration. Those assumptions are not measured performance for your own boiler. A nameplate or product rating also does not prove the annual seasonal efficiency in a particular installation. Controls, operating temperatures and system setup can affect real performance, so the calculated difference remains an estimate rather than a promised annual saving.
Use actual energy information where possible
Annual gas use can include cooking and other loads as well as heating and hot water. Treating all of it as boiler fuel can exaggerate a replacement saving. Likewise, replacing a gas boiler with another fuel requires a consistent useful-heat comparison, not simply applying a gas price to the new appliance’s electricity consumption.
Use actual bills and a sensible estimate of heating demand where available. The current cap gas-rate token is 7.97p per kWh, but your own tariff may differ. The running-cost calculator can provide context using its existing assumptions and inputs. Do not substitute an unrelated tariff rate, a future forecast or an unsourced percentage reduction to make a replacement appear attractive.
Payback is a planning method, not a guarantee
Simple payback divides the extra upfront investment by the estimated annual saving, when that saving is positive. The result depends on the price you pay, assumed efficiency, heat demand and future fuel prices. A zero or negative fuel saving does not produce a useful payback calculation. Do not promise that replacing a working boiler will always recover its cost.
Include relevant servicing and warranty conditions in the broader decision, and distinguish replacing a failed appliance from choosing to replace a functioning one early. Avoid adding uncertain savings from several unrelated changes together. Better controls or insulation may alter heat demand independently, so model them separately rather than assigning their whole benefit to the new boiler.
Check help and alternatives before committing
The existing ECO4 grants article explains how to check assistance against published criteria. It is not proof that every boiler quote qualifies or that a new grant award is available. Verify the current official scheme information and eligibility before relying on support in your budget. No grant value or deadline has been invented in this guide.
Heat pumps are a separate option and need a property and system assessment. Use the heat pump pages to understand the different efficiency model, installation considerations and official scheme links. Obtain comparable written scopes before deciding. This guide does not arrange finance, recommend credit or assert that one technology is suitable for every household.
Make your next comparison useful
Put the itemised quote beside the calculator assumptions. Replace the upfront estimate with the actual quoted scope when reviewing payback, and keep the chosen fuel rates and heating demand visible. Ask the installer to explain any savings claim that uses a different tariff or an unexplained starting boiler efficiency.
The original boiler tool remains focused in search on running costs, while this guide handles the installation decision. Read back through the quote for exclusions and warranty obligations before signing. If the main problem is unaffordable heating rather than a failed boiler, use support guidance as well as efficiency comparisons. A calculator output is an estimate, not an installation recommendation or guarantee that the quoted price is fair.