Heat Pump Savings Calculator: Boiler Replacement ROI

Heat pump vs boiler: savings, SCOP and payback period

The tool derives your heat demand from your current bill, divides it by the heat pump's SCOP to get its electricity use, then compares the two yearly costs. With €2,200 of gas per year, a SCOP of 3.8 and electricity at €0.2003/kWh, savings reach about €1,286 a year and the €9,500 net investment pays back in 7.4 years.

The formula

• Heating energy (kWh) = current bill ÷ price per kWh of the current fuel. Prices used by the tool: gas €0.158/kWh, heating oil €0.142/kWh, pellets €0.085/kWh, electric heaters at the electricity price you enter.
• Heat pump use = energy ÷ SCOP; heat pump cost = use × electricity price + yearly servicing.
• Savings = current bill − heat pump cost; payback = (installation cost − grants) ÷ yearly savings.
• CO₂: 0.227 kg/kWh for gas, 0.300 for oil, 0.085 for electric heaters, 0.030 for pellets and 0.075 for the heat pump's electricity.

Worked example (default values)

Gas bill of €2,200: 13,924 kWh. With a SCOP of 3.8, the heat pump uses 3,664 kWh, i.e. €734 of electricity + €180 of servicing = €914. Savings: €1,286 a year (58.5%). Installation €13,500 minus €4,000 of grants: €9,500 paid back in 7.4 years; net gain €3,361 over 10 years and €16,221 over 20 years. CO₂ avoided: 2,886 kg a year.

Limits

The efficiency of the existing boiler is ignored: all purchased energy counts as useful heat, which slightly overstates the heat pump's consumption. The gas price used excludes the standing charge, so enter your bill without it. Floor area is not used, and prices are frozen. SCOP, measured under standard EN 14825, depends on climate and on the flow temperature of your radiators. Grants are entered by hand. This is an estimate and does not replace an installer's survey or an energy adviser.

Sources and dates: electricity €0.2003/kWh incl. tax, French regulated Base tariff 6 kVA in force on 01/08/2026 (CRE decision no. 2026-147, annex B, plus excise duty and 20% VAT); gas €0.158/kWh, CRE benchmark price for heating customers, GRDF area, on 01/11/2026; French MaPrimeRénov' per-measure grant for an air-to-water heat pump: €5,000, €4,000 or €3,000 depending on income (spending capped at €12,000), nothing for higher incomes, page checked on 01/09/2026; oil and pellet prices and CO₂ factors are indicative values, not verified (checked 14/10/2026).

Frequently Asked Questions

How much does a heat pump save compared with gas?

With a gas bill of €2,200 a year, a SCOP of 3.8 and electricity at €0.2003/kWh, the tool works out about €1,286 of savings a year, including €180 of servicing, or 58.5% of the bill. The higher the SCOP, the larger the gap.

What is the difference between COP and SCOP?

COP measures efficiency at one moment, at fixed test temperatures. SCOP, defined by standard EN 14825, is a seasonal average over the whole heating season, and it is the figure to enter in the tool. A SCOP of 3.8 means 3.8 kWh of heat for 1 kWh of electricity.

How much does France's MaPrimeRénov' pay for an air-to-water heat pump?

Under the per-measure scheme, the grant is €5,000 for very low-income households, €4,000 for low-income and €3,000 for middle-income households, on spending capped at €12,000; higher incomes are not eligible (service-public.gouv.fr, page checked on 01/09/2026). Energy-saving certificate (CEE) bonuses can be added within an overall cap.

How long does a heat pump take to pay for itself?

The tool divides the net investment (installation minus grants) by the yearly savings. With €13,500 of installation, €4,000 of grants and €1,286 saved per year, payback is 7.4 years. It does not account for future energy price rises.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.