Heat Pump vs Gas Boiler
Work out what a hybrid or full heat pump saves per year compared with a gas boiler, and how many years it takes to pay back.
Pays back after
47 years and 7 months
Saving per year
£126.00
Cost with a gas boiler per year
£720.00
Cost with a heat pump per year
£594.00
Extra electricity per year
2,700 kWh
Less gas per year
9,000 kWh
Please note: This is an example calculation, not financial advice. Personal circumstances, changes in rules and rates, and additional costs are not included. If in doubt, talk to a financial adviser.
Maintenance, the lifespan of the boiler and the heat pump, and changing energy prices are not included.
How this number is calculated
The blocks use your input. Change a value above and they update with it.
Step 1 · Heat your home needs
Step 2 · Heat from the heat pump
Step 3 · Electricity for the heat pump
Step 4 · Gas you still use
Step 5 · Cost with a gas boiler
Step 6 · Cost with a heat pump
Step 7 · Saving per year
Step 8 · Pays back after
How the calculation works
Work out what a heat pump saves compared with a gas boiler alone. Enter your gas use for heating, the energy prices, the efficiency of the heat pump and its cost, and see the saving per year and the payback period.
First the calculator works out how much heat your home needs: the gas for heating times its energy content times the boiler efficiency. The heat pump supplies part of that heat, using electricity: the heat divided by its efficiency (SCOP). The rest of the heat still comes from gas. The cost with a heat pump is the remaining gas plus the electricity, minus the fixed gas charges if you stop using gas. The difference with the boiler alone is the saving; the cost divided by the saving is the payback period.
Formula
Heat (kWh) = gas in kWh × boiler efficiency. Heat pump electricity = heat × heat pump share ÷ SCOP. Cost with heat pump = gas × (1 − share) × gas price + electricity × electricity price − fixed charges saved. Saving = gas × gas price − cost with heat pump. Payback = cost ÷ saving.
Assumptions
- Internally the calculator uses Dutch gas at 9.77 kWh per m³. kWh and therms convert exactly; UK and US gas holds more energy per m³.
- Energy prices stay the same. If gas rises faster than electricity, the heat pump pays back sooner.
- The SCOP is a seasonal average. With high flow temperatures and poor insulation it is lower.
- Maintenance, a new boiler and the lifespan of the heat pump are not included.
- The payback period is rounded to whole months, amounts to the cent.
Example calculations
The button fills in the calculator above, so you can carry on from there.
-
Hybrid heat pump
Pays back after
8 years and 7 months
Gas for heating per year 900 m³ · Gas price £1.35 per m³ · Electricity price per kWh £0.27 · Heat from the heat pump (%) 70 · Heat pump efficiency (SCOP) 4 · Boiler efficiency (%) 90 · Cost after grants £4,075.00 · Fixed gas charges saved per year £0.00 · m³
-
Full heat pump
Pays back after
9 years and 4 months
Gas for heating per year 900 m³ · Gas price £1.35 per m³ · Electricity price per kWh £0.27 · Heat from the heat pump (%) 100 · Heat pump efficiency (SCOP) 3.5 · Boiler efficiency (%) 90 · Cost after grants £8,975.00 · Fixed gas charges saved per year £360.00 · m³
-
With your own solar power
Pays back after
6 years and 4 months
Gas for heating per year 900 m³ · Gas price £1.35 per m³ · Electricity price per kWh £0.15 · Heat from the heat pump (%) 70 · Heat pump efficiency (SCOP) 4 · Boiler efficiency (%) 90 · Cost after grants £4,075.00 · Fixed gas charges saved per year £0.00 · m³
Frequently asked questions
What does a heat pump save?
It depends mostly on the ratio between the electricity and gas prices. With 9,000 kWh of gas for heating at 0.08 per kWh, electricity at 0.26 and a full heat pump with SCOP 3, the saving is 126.00 a year, and a cost of 6,000 takes 47 years and 7 months to pay back. With a heat pump tariff of 0.15 per kWh, the saving is 423.00 and the payback 14 years and 2 months.
Why is the saving sometimes small?
A heat pump uses electricity, which costs several times more per kWh than gas. If the electricity price divided by the gas price is close to the SCOP, the running costs are about the same. A higher SCOP, a cheaper electricity tariff or your own solar power makes the difference.
What is the SCOP?
The seasonal efficiency: how many kWh of heat the heat pump delivers on average per kWh of electricity over the heating season. A SCOP of 4 means 4 kWh of heat from 1 kWh of electricity. The better the insulation and the lower the flow temperature of the heating, the higher the SCOP.
Hybrid or full heat pump?
A full heat pump replaces the boiler and lets you drop the gas supply and its standing charge, but costs more. A hybrid keeps the boiler for the coldest days and hot water. Compare both by changing the share of heat from the heat pump.
Which grants are included?
None automatically: enter the cost after any grant, rebate or tax credit you qualify for, such as the Boiler Upgrade Scheme in England and Wales (7,500 towards an air source heat pump, not for hybrids). Schemes and amounts change, so check what applies to you.
Sources and checks
Sources
- Apply for the Boiler Upgrade Scheme: what you can get | GOV.UK
- Gas meter readings and bill calculation | GOV.UK
- Energy price cap unit rates and standing charges | Ofgem
- Heat pumps 3 x more efficient than boilers | Energy Systems Catapult
How we check it
This calculator has 12 fixed checks: 8 calculations with a result that is fixed in advance, and 4 cases of invalid input that must be rejected. They all run automatically every time we publish; if one fails, the calculator does not go live.
See the calculations
- Gas for heating per year 900 m³ · Gas price £1.35 per m³ · Electricity price per kWh £0.27 · Heat from the heat pump (%) 70 · Heat pump efficiency (SCOP) 4 · Boiler efficiency (%) 90 · Cost after grants £4,075.00 · Fixed gas charges saved per year £0.00 · m³ → Pays back after 8 years and 7 months
- Gas for heating per year 900 m³ · Gas price £1.35 per m³ · Electricity price per kWh £0.27 · Heat from the heat pump (%) 100 · Heat pump efficiency (SCOP) 3.5 · Boiler efficiency (%) 90 · Cost after grants £8,975.00 · Fixed gas charges saved per year £360.00 · m³ → Pays back after 9 years and 4 months
- Gas for heating per year 600 m³ · Gas price £1.35 per m³ · Electricity price per kWh £0.27 · Heat from the heat pump (%) 70 · Heat pump efficiency (SCOP) 4 · Boiler efficiency (%) 90 · Cost after grants £4,075.00 · Fixed gas charges saved per year £0.00 · m³ → Pays back after 12 years and 10 months
- Gas for heating per year 900 m³ · Gas price £1.35 per m³ · Electricity price per kWh £0.40 · Heat from the heat pump (%) 70 · Heat pump efficiency (SCOP) 4 · Boiler efficiency (%) 90 · Cost after grants £4,075.00 · Fixed gas charges saved per year £0.00 · m³ → Pays back after 13 years and 9 months
- Gas for heating per year 900 m³ · Gas price £1.35 per m³ · Electricity price per kWh £0.15 · Heat from the heat pump (%) 70 · Heat pump efficiency (SCOP) 4 · Boiler efficiency (%) 90 · Cost after grants £4,075.00 · Fixed gas charges saved per year £0.00 · m³ → Pays back after 6 years and 4 months
- Gas for heating per year 9,000 kWh · Gas price £0.08 per kWh · Electricity price per kWh £0.26 · Heat from the heat pump (%) 100 · Heat pump efficiency (SCOP) 3 · Boiler efficiency (%) 90 · Cost after grants £6,000.00 · Fixed gas charges saved per year £108.00 · kWh → Pays back after 47 years and 7 months
- Gas for heating per year 9,000 kWh · Gas price £0.08 per kWh · Electricity price per kWh £0.15 · Heat from the heat pump (%) 100 · Heat pump efficiency (SCOP) 3 · Boiler efficiency (%) 90 · Cost after grants £6,000.00 · Fixed gas charges saved per year £108.00 · kWh → Pays back after 14 years and 2 months
- Gas for heating per year 400 therms · Gas price £1.80 per therm · Electricity price per kWh £0.17 · Heat from the heat pump (%) 100 · Heat pump efficiency (SCOP) 3.5 · Boiler efficiency (%) 90 · Cost after grants £8,000.00 · Fixed gas charges saved per year £0.00 · therms → Pays back after 38 years and 6 months
Changes
- : First version. Defaults follow the Ofgem price cap (gas 0.08, electricity 0.26, standing charge 108) and SCOP 3; the m³ option is now marked as Dutch gas. Sources added.
Last reviewed: · How we build and check our calculators
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