Project Cost Estimators
HVAC / Boiler Replacement Cost Calculator
Estimates supply and install cost for boiler, heat pump, or furnace
Updated 27 May 2026 · Live
What this tool does
Estimates supply and install cost for boiler, heat pump, or furnace.
HVAC / Boiler Replacement Cost Calculator — enter the boiler output ({boiler_kw} kW), number of radiators ({radiators}), specification tier, and VAT rate to get an estimated supply-and-install cost of {result}, including a 10% contingency and VAT.
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Formula Used
How the hvac / boiler replacement cost calculator works
Estimates supply and install cost for boiler, heat pump, or furnace. The calculator takes your dimensions and supplier rates, applies a standard UK trade formula, and returns a quantity with an indicative cost. Every figure is an estimate — site conditions always move the final number.
Typical UK project cost estimators wastage
Cost estimates carry an inherent range — a ±20% spread is normal at planning stage, tightening to ±5% once drawings are tendered. Our defaults reflect common UK trade allowances, and can be adjusted upwards for non-standard geometry or downwards where experience supports a lower figure.
What this tool does not do
It does not replace a professional quote, factor regional pricing, assess structural adequacy, or confirm Building Regulations compliance. Those remain the responsibility of a suitably qualified designer, surveyor, or your building control officer.
On-site considerations for hvac / boiler replacement cost
Rates in this tool are April 2026 UK medians. Regional variation of ±30% is normal — London and the South East run higher, Scotland and the North typically lower.
Building Regulations and compliance
VAT treatment differs by project type: new-builds are zero-rated for a qualifying end user, listed-building work may qualify for 5%, normal renovation is 20%. When in doubt, a pre-application enquiry to the local authority can give early clarity, which tends to be less costly than retrospective correction.
Before you order
Break your budget into build cost, professional fees (8–15%), and contingency (10–20%) from the outset. Blending them hides overruns until it is too late to respond. Cross-checking the calculator’s output against a supplier quote helps catch differences in pricing assumptions — ask for exact product specifications (grade, finish, batch number) and confirm delivery timescales against your programme.
Adjusting the defaults
Every input in this calculator is editable. Enter your own dimensions, supplier prices, and wastage allowance — the output recalculates instantly. If the defaults feel off for your region or project type, your own numbers always override them.
Using this hvac / boiler replacement cost calculator alongside other BuildMetricLab tools
This calculator works best as part of a planning workflow. Pair the quantity with our project contingency, labour-hours, and material-cost calculators to build a complete estimate before you pick up the phone to a supplier. All BuildMetricLab tools run entirely in your browser — no sign-up, no data sent anywhere, and every formula is shown on-page so you can audit the maths.
Sources & methodology
Estimates supply and install cost for boiler, heat pump, or furnace. Every result is calculated from the values you enter, and all inputs are editable.
Frequently asked questions
Are hvac / boiler replacement cost calculator results accurate enough to order materials?
Use them as a starting estimate only. Verifying the final quantity with your supplier or contractor before ordering is good practice — site conditions, wastage and cut-offs all affect the true figure.
How is the contingency figure calculated?
The calculator adds a flat 10% contingency on top of the boiler, radiator, and controls subtotal to allow for minor variations such as additional pipework, access difficulties, or small unforeseen works. This is a planning allowance, not a wastage percentage — increase your own budget further for older properties or where the system layout is not yet fully surveyed.
Does this replace professional advice?
No — this tool does not substitute for a suitably qualified professional. For works that affect structure, Building Regulations, Party Wall matters, gas, electrics, drainage to a public sewer, or similar, consult a Gas Safe registered engineer or other qualified professional as applicable.
Can I change the unit prices?
Yes — every price field is editable. Plug in your supplier's quote to get a total that matches your project.
Spotted something off?
Calculations or display — let us know.
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