Compare the complete installed systems at the same comfort and hot-water requirement. A heat pump and a gas boiler use different fuels, temperatures and equipment, so appliance price or headline efficiency alone cannot decide.

Model annual energy, not labels

Estimate useful heat demand, then divide by cautious in-use efficiency or seasonal performance to estimate fuel. Multiply by current tariffs and keep standing charges separate. Run low, central and high cases. Do not assume a grant, special tariff or predicted saving until eligibility and terms are verified.

Will radiators change?

Maybe. Compare each room’s heat loss with emitter output at the proposed flow and return temperatures. Fabric improvement or larger emitters may be part of a heat-pump design; an existing radiator is not automatically unsuitable.

Include transition work

Compare cylinder, pipework, controls, electrical capacity, external unit base, condensate, flue removal, fuel disconnection, decoration and commissioning. A quote excluding necessary enabling work is not comparable.

Comfort and operation

Discuss schedules, recovery, noise, zoning and backup arrangements. Heat pumps commonly favour longer operation at lower temperatures; replacing a boiler without improving controls or system setup can also miss efficiency.

Frequently asked questions

Will my radiators need changing?

Only a room-by-room output check can answer. Some may be adequate, some may need changing, and fabric improvements may reduce the requirement.

Which tariff and efficiency assumptions affect the comparison?

Electricity and gas unit prices, standing charges, seasonal heat-pump performance, boiler in-use efficiency, hot-water demand and any time-of-use pattern.

Suggested on-page component

Embed a Whole-System Running-Cost Scenario Tool with editable tariffs, demand and performance ranges. No preset savings or grant eligibility.

Related guides

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