Heat Pump Purchase Calculator
Heat pump install cost vs gas boiler running cost saving
Payback calculator for a heat pump vs gas boiler using install cost plus annual running-cost savings — see when the lower bills cover the install.
What this tool does
Enter heat pump and boiler install costs, annual heating demand, heat pump COP, boiler efficiency, and fuel rates to compare the upfront price difference against long-term running cost differences. The calculator estimates annual energy costs for both systems by dividing heat demand by efficiency (or COP for the heat pump) and multiplying by fuel rates. It then shows how many years of lower running costs offset the install price premium. Results illustrate the relationship between equipment cost, efficiency performance, and fuel price assumptions over your chosen timeframe. The output is educational and based on the inputs provided—actual savings depend on real-world installation specifics, system performance, and fuel price changes over time, which aren't modelled here.
Enter Values
People also use
Major Purchases
New Boiler Cost Calculator
Payback calculator for replacing an old gas boiler with a new higher-efficiency model — see how many years of energy savings cover the install.
Green & Sustainable Finance
Solar Panel ROI Calculator
Calculate the financial return on solar panel installation costs using payback period, annual savings projections, and long-term ROI analysis.
Major Purchases
Dishwasher Purchase Calculator
Calculate dishwasher payback including water savings and time recovered — see when the appliance pays for itself across utility bills and minutes.
Formula Used
Spotted something off?
Calculations or display — let us know.
Disclaimer
Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.
Where the Running-Cost Advantage Comes From
A heat pump with COP 3 delivers 3 kWh of heat per 1 kWh of electricity. A gas boiler at 90% efficiency delivers 0.9 kWh of heat per 1 kWh of gas. When electricity is 3x the per-kWh price of gas, the two fuels cost roughly the same to run; when electricity is 2x or less, heat pumps win; above 3.5x, gas wins on running cost.
The Install Premium Matters
Heat pump installs typically run 8,000-15,000 (less government grants of 7,500 via BUS). A new gas boiler averages 2,500-4,500 installed. The premium is 3,000-10,000 after grants. That premium sets the hurdle the running-cost saving must clear over the appliance's 15-20 year life.
What This Calculator Does Not Model
Emissions savings are not priced. Building fabric upgrades (insulation, larger radiators) are not included. Heat pump output varies with outside temperature — cold snaps reduce COP. The calculator uses a single flat COP as an illustrative number rather than a full dynamic model.
Run it with sensible defaults
Using heat pump installed cost of 10,000, gas boiler installed cost of 3,500, annual heating demand of 12,000, heat pump cop of 3, the calculation works out to 15.6 yrs. The defaults are meant as a starting point, not a recommendation.
The levers in this calculation
The inputs — Heat Pump Installed Cost, Gas Boiler Installed Cost, Annual Heating Demand, Heat Pump COP, and Electricity Rate — do not pull with equal force. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.
How the math works
Heat pump running cost equals heat demand divided by COP times electricity rate. Boiler running cost equals heat demand divided by boiler efficiency times gas rate. Payback divides install premium by annual saving. Results are estimates for illustration purposes only.
When the result says "wait"
If the payback is longer than you expect to keep the item, the math says no. That's useful information — not everything has to earn its keep financially, but knowing when something doesn't means the decision to buy it anyway is deliberate.
What this doesn't capture
Purchase decisions rarely come down to payback alone. Reliability, time saved, enjoyment, and alternatives outside the calculation all matter. The figure gives you the money side cleanly so you can weigh it against everything else honestly.
Heat pump payback vs boiler over 15,000 kWh kWh demand is 15.6 yrs.
Inputs
This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.
Sources & Methodology
Methodology
Heat pump running cost equals heat demand divided by COP times electricity rate. Boiler running cost equals heat demand divided by boiler efficiency times gas rate. Payback divides install premium by annual saving. Results are estimates for illustration purposes only.
Frequently Asked Questions
What COP to use?
Include the BUS grant?
Does this model radiator upgrades?
What about cold-weather performance?
Related Calculators
More Major Purchases Calculators
Major Purchases
3D Printer ROI Calculator
Calculate ROI on a 3D printer from purchase price, filament cost, and equivalent retail savings per print, with months until break-even.
Major Purchases
Air Fryer vs Oven Calculator
Work out the energy-cost payback period for an air fryer vs a conventional oven. Enter both prices and per-meal energy use to see when it pays back.
Major Purchases
Air Purifier Worth It Calculator
What an air purifier costs to run for a year — amortised purchase, filter replacements, and electricity at your local rate.
Major Purchases
Allotment vs Supermarket ROI Calculator
Calculate whether your allotment rent plus costs produces enough equivalent value to beat supermarket produce. Honest ROI including time.
Major Purchases
Bathroom Renovation Cost Calculator
Calculate realistic bathroom renovation cost including materials, fittings, labour, plumbing, and contingency for unexpected extras.
Major Purchases
Biweekly Auto Payment Calculator
Calculate interest savings from biweekly versus monthly auto loan payments — see how much an extra payment per year actually saves.
Explore Other Financial Tools
Digital Nomad & Freelance
The Quit My Job Runway Calculator
Calculate financial runway and how long savings last after leaving employment. Determine months of expenses covered by existing funds.
SaaS & Subscription
Gross Revenue Retention Calculator
Calculate gross revenue retention from starting MRR, churned MRR, and contraction MRR — the SaaS health number that excludes upsells.
Business & Startup
Debt to Net Worth Ratio Calculator
Calculate debt-to-net-worth ratio as a measure of financial resilience — what proportion of your gross position is funded by liabilities.