Energy Saving Trust’s current comparison puts a typical air-source installation near £12,000 and notes that well-designed heat pumps can be more than three times as efficient as oil or gas boilers. Efficiency alone does not decide the household choice. Fuel prices, useful heat demand, emitter design, standing charges, capital work and desired comfort must be placed on the same boundary.
For 1 October–31 December 2026, Ofgem reports average Direct Debit rates of an electricity figure of 26.32p/kWh and a gas figure of 7.97p/kWh. Those values are temporary and national. Put the tariffs offered to the household into both heating calculations and test a different future ratio, because today’s unit-price relationship is not guaranteed for the equipment lifetime.
A boiler replacement and a heat-pump retrofit are not equivalent scopes. The heat-pump project may include radiators, cylinder, controls and electrical work that a boiler quote leaves untouched. Compare the whole-heating-system outcome, not just the appliance price.
Comfort also differs. Heat pumps commonly maintain steadier temperatures with longer operating periods, whereas boilers often deliver short high-temperature bursts. Either can be uncomfortable when badly designed or controlled.
What changes the answer
Energy conversion
Use seasonal heat-pump efficiency and realistic boiler seasonal efficiency, not product headline figures.
Tariffs
Electricity and gas prices change independently. Test more than one ratio and any heat-pump tariff.
Upfront support
BUS can materially reduce an eligible heat-pump contribution; boiler replacement does not receive that grant.
Emitters and water
Heat-pump radiator and cylinder requirements can add work but also modernise the heating system.
Maintenance
Compare manufacturer servicing, warranty conditions and local engineer availability.
Carbon and resilience
A heat pump removes on-site combustion but increases reliance on electrical capacity; neither guarantees operation in a power cut.
Illustrative worked example
Illustrative example — both systems must deliver 10,000 kWh of heat. At SCOP 3.2, a heat pump uses 10,000 ÷ 3.2 = 3,125 kWh; at 26.32p, variable cost is £822.50. At 85% seasonal boiler efficiency, gas use is 10,000 ÷ 0.85 = 11,765 kWh; at 7.97p, variable cost is £937.65. The heat-pump difference is £115.15 before standing charges. Use Ofgem’s rates only for this stated cap period and insert the home’s forecast.
Rules and responsibilities for this topic
Heat-pump design
MCS heat-loss, emitter and performance evidence should underpin a grant-supported installation.
Gas work
Boiler installation and decommissioning must be completed by appropriately registered competent people.
Planning and discharge
Heat-pump siting and condensate need assessment; boiler flue and condensate rules differ.
Compare two different ways of heating
Convert present gas use into useful heat by allowing for the boiler’s seasonal efficiency. Then divide the same heat demand by the proposed heat pump’s seasonal performance factor to estimate electricity use. Apply current household tariffs to each fuel and keep standing charges separate. If gas cooking or a fire remains, the gas standing charge will not disappear. This method is more defensible than comparing unit prices alone.
Compare capital work on equal boundaries. A boiler quote may reuse radiators, cylinder and pipework, while a heat-pump proposal may include emitters, controls and electrical upgrades. Record expected equipment life, maintenance, finance and available support without assuming future energy prices. Comfort also differs: low-temperature systems often run for longer periods, so discuss heating schedules, noise and hot-water recovery with everyone in the home.
Ask the heat-pump designer for room heat losses, emitter outputs and forecast seasonal efficiency. Ask the boiler installer for controls, system cleaning, flue work and the expected efficiency of the complete installation. Consider carbon goals separately from the cash calculation so neither is hidden. The quote checker can place missing evidence beside each proposal. The better choice depends on the building, tariffs and priorities, not a universal claim that one technology always costs less.
Disruption and future work can alter the choice. Replacing a boiler may be quicker, while a low-temperature conversion can involve radiator, cylinder, pipe and electrical changes. On the other hand, completing planned insulation or renovation at the same time may reduce duplicated labour. Ask both installers to describe what the home will look like when work finishes, how long heating and hot water will be unavailable, and which decorations or floors need reinstatement. Price those consequences instead of comparing appliance boxes alone.
Compare replacement risks as well as first-year cost
A boiler may fit familiar pipework but retains combustion, flue and gas-supply considerations. A heat pump removes on-site combustion yet introduces an outdoor fan unit, refrigeration circuit and greater reliance on electricity. Ask each contractor about likely component replacement, service access and emergency support. Record whether the quotation preserves any existing cylinder or controls and who accepts responsibility for compatibility. These questions do not produce a single winner, but they prevent a short payback table from hiding practical differences that will remain long after installation day.
Questions to ask the installer
- What efficiencies are assumed for both systems?
- Are standing charges treated consistently?
- Which radiator and cylinder work differs between quotes?
- What BUS support is confirmed?
- How do comfort schedules compare?
- What are the ten-year maintenance and replacement assumptions?
Frequently asked questions
Are heat pumps more efficient than gas boilers?
Yes in energy terms: heat pumps move heat and can deliver several units of heat per unit of electricity, while boilers cannot deliver more useful heat than their fuel contains. Cost still depends on the much higher price per unit of electricity.
Will a heat pump heat the home properly?
A correctly sized and commissioned system should meet the calculated design heat loss. Comfort failures usually point to design, emitter, control or building problems rather than the technology label. Require room calculations and output at the design outdoor temperature.
Is a gas boiler cheaper to install?
A straightforward boiler swap is often lower in upfront scope, while a heat pump may need emitters, cylinder and electrical work. BUS support can narrow or reverse the customer-cost difference. Compare complete itemised quotations rather than appliance prices.
Do heat pumps need more maintenance?
Requirements vary by product and warranty. Ask both installers for servicing schedules, likely consumables, remote-monitoring support and labour cover. A heat pump has no combustion flue, while a boiler requires gas-safety and combustion checks.
Should I keep gas as backup?
Keeping gas can provide operational flexibility but retains standing charges, servicing and two systems. A hybrid design needs clear controls and carbon and cost logic. Do not retain a boiler simply because the heat-pump design has not been completed properly.
Independent sources
- Energy Saving Trust, Air source heat pumps (accessed 3 October 2026)
- Ofgem, Boiler Upgrade Scheme (accessed 3 October 2026)
- Ofgem, Price-cap unit rates (accessed 3 October 2026)
- MCS, Standards and tools library (accessed 3 October 2026)
Last updated .