Running-cost comparison only, using the tariffs you enter. It excludes standing charges, installation cost, grants (e.g. the Boiler Upgrade Scheme) and servicing. Real heat pump SCOP depends on the system design and how low the flow temperature runs; a poorly designed system will cost more than this suggests.
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This calculator compares what a heat pump and a gas boiler cost to run over a year for the same heat demand. Enter the annual heat demand, your gas and electricity tariffs, the boiler efficiency and the heat pump's SCOP, and it shows the running cost of each and the difference.
It is the question every customer weighing up a heat pump asks, and one heating engineers get drawn into on site. Because a heat pump moves heat rather than burning fuel, it delivers several units of heat per unit of electricity — but electricity costs far more than gas per unit, so which wins depends on the numbers.
The comparison divides the heat demand by each system's efficiency to find the fuel it uses, then applies your tariffs. A gas boiler at 90% burns slightly more gas than the heat delivered; a heat pump with a SCOP of 3.2 uses roughly a third as much electricity as the heat it produces.
Gas cost = (heat demand ÷ boiler efficiency) × gas price; Heat pump cost = (heat demand ÷ SCOP) × electricity price
For the boiler, the heat demand is divided by its seasonal efficiency to find the gas burned, then multiplied by the gas unit price. For the heat pump, the heat demand is divided by its Seasonal Coefficient of Performance (SCOP) — the average units of heat per unit of electricity — to find the electricity used, then multiplied by the electricity unit price.
Enter the heat the home needs over a year in kWh. A typical UK house is around 12,000 kWh for heating and hot water; a well-insulated home is less, a large or draughty one more.
Enter the gas and electricity unit rates in pence per kWh from a recent bill. The gap between them is the single biggest factor in the comparison, so use real figures rather than the defaults.
Enter the boiler's seasonal efficiency (around 90% for a modern condensing boiler) and the heat pump's SCOP — typically 3.0 to 4.0 depending on the design and flow temperature.
The calculator shows each system's annual running cost and which is cheaper by how much.
The SCOP is where heat pump economics are won or lost. A heat pump running a well-designed system at a low flow temperature might achieve a SCOP of 4; the same unit forced to feed undersized radiators at a high flow temperature might only manage 2.5, which changes the answer entirely. Be realistic about the SCOP the actual installation will deliver.
This compares running cost only. It ignores standing charges, the installation cost, grants such as the Boiler Upgrade Scheme, and servicing — all of which matter to the customer's overall decision. A heat pump can have a higher or similar running cost yet still make sense once a grant and low-carbon heating are factored in, or the reverse.
Tariffs move, and special heat pump electricity tariffs exist that narrow the gap considerably. Run the comparison on the customer's actual rates, and if they are considering a heat-pump-specific tariff, run it again on those figures. Treat the output as a guide to inform the conversation, not a guaranteed saving.
Running-cost comparison only, using the tariffs you enter. It excludes standing charges, installation cost, grants (e.g. the Boiler Upgrade Scheme) and servicing. Real heat pump SCOP depends on the system design and how low the flow temperature runs; a poorly designed system will cost more than this suggests.
It can be, but it is close and depends on the numbers. A heat pump uses far less energy than a boiler, but electricity costs three to four times more than gas per unit, so the saving hinges on the SCOP and your tariffs. A well-designed heat pump on a good tariff often edges it; a poorly designed one on a standard tariff may cost more. Enter your figures above.
SCOP is the Seasonal Coefficient of Performance — the average number of units of heat a heat pump delivers per unit of electricity it uses, across a whole heating season. A SCOP of 3.2 means 3.2 kWh of heat for every 1 kWh of electricity. The higher the SCOP, the cheaper the heat pump is to run.
A typical UK house uses roughly 12,000 kWh a year for heating and hot water, though it ranges widely — a well-insulated modern home may use half that, while a large or poorly insulated property uses considerably more. Use the customer's actual gas usage from their bills where you can, as it is the best guide to their heat demand.
No — it compares running cost only. The upfront installation cost, grants such as the Boiler Upgrade Scheme, standing charges and servicing all sit outside this calculation but matter to the overall decision. Use the running-cost comparison as one input alongside those figures, not as the whole picture.
Estimate whole-house heat loss and the boiler or heat pump size to match.
Convert a radiator’s catalogue output to the output at your system’s ΔT.
Time and energy to heat a hot water cylinder.
Required circulation flow for a heat load at a design ΔT.
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