Oil boiler or heat pump, now vs. 2025
Heating oil costs 1.93 EUR a litre in France and 1.71 in Germany, and a heat pump looks like the obvious way to cut the bill. Would it still pay if oil fell back to its 2025 price? In France, yes, clearly: at the 2025 average the heat pump still saves 674 EUR a year, and it stays cheaper to run until oil falls to 0.62 EUR a litre, a little over half that average. In Germany the 2025 price leaves a saving of 188 EUR a year, a payback of 127 years even after the grant, so there the answer depends on oil staying high.
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Heating oil costs 1.93 euros a litre in France, 1.71 in Germany. A heat pump looks like the easy saving. Would it still pay at the 2025 price?
In France, yes, clearly. The heat pump stays cheaper to run until oil falls to 0.62 euros a litre. In Germany, at the 2025 price, it saves only 188 euros a year.
Oil in France averaged 1.13 euros a litre in 2025. In one week of March it jumped 26 percent. In October: 1.93.
Two nineties houses, original radiators kept. The oil boiler burns 1,322 litres a year near Nancy, hot water included, and 1,835 near Kassel. The heat pump does the same job on 3,828 and 4,989 kilowatt hours of electricity.
Running cost at today's oil price. Nancy: 2,572 euros a year with oil, 843 with the heat pump. Kassel: 3,175 against 1,603.
At the 2025 price the gap narrows. Nancy still saves 674 euros a year. Kassel saves 188.
After a typical grant, the heat pump costs about 9,290 euros in Nancy and 23,820 in Kassel. It pays back in 5 and 15 years at today's oil price, 14 and 127 at the 2025 price.
Your house burns its own amount of oil. Run it at EnergyFlow dot tech, and see your litres and your running cost.
How many litres of oil, and how much electricity instead
I ran two detached 1990s houses for a year: 120 m² near Nancy and 140 m² near Kassel. Each keeps its original radiators and heats its hot water through a cylinder, first with an oil boiler, then with a heat pump. Same house, same weather, same comfort target. Only the heat source changes.
| One year | Nancy, France (120 m²) | Kassel, Germany (140 m²) |
|---|---|---|
| Oil boiler, litres of oil | 1,322 | 1,835 |
| of which for hot water, litres | 364 | 365 |
| Heat pump, kWh of electricity | 3,828 | 4,989 |
| Heat pump, COP over the year | 2.7 | 2.9 |
The Nancy boiler burns 1,322 litres a year, 364 of them for hot water. The Kassel boiler burns 1,835, 365 for hot water.
The heat pump does the same job on 3,828 kWh and 4,989 kWh of electricity. Its COP over the year is 2.7 in Nancy and 2.9 in Kassel, because it takes heat from the outside air instead of making it.
What oil costs now, and what it cost in 2025
Heating oil cost 1.93 EUR per litre in France and 1.71 in Germany in the week of 19 October 2026 (national averages with taxes, EU Weekly Oil Bulletin). The 2025 average was 1.13 and 0.96. That is about 70 percent more in France and about 79 percent more in Germany.
The rise came in one week. Between the weeks of 2 and 9 March 2026 the price went up 26 percent in France and 20 percent in Germany. I use the 2025 average as the price before that jump.
- Nancy, France
- Kassel, Germany
What each system costs to run
Running cost is the oil, or the heat pump's electricity, plus the electricity of the boiler's pumps and controls. Electricity costs 0.2203 EUR per kWh in France and 0.3214 in Germany (Eurostat household prices with all taxes, first half of 2026). Installation and grants come further down.
| One year, EUR | Nancy, France | Kassel, Germany |
|---|---|---|
| Oil boiler, oil at the price of 19 October 2026 | 2,572 | 3,175 |
| Oil boiler, oil at the 2025 average | 1,517 | 1,792 |
| Heat pump | 843 | 1,603 |
| Heat pump saving, today's price | 1,729 | 1,571 |
| Heat pump saving, 2025 average | 674 | 188 |
| Break-even oil price, EUR per litre | 0.62 | 0.86 |
In Nancy the break-even is 0.62 EUR per litre, a little over half the 2025 average. At today's price the heat pump saves 1,729 EUR a year, at the 2025 average 674. Oil would have to fall to 0.62 before the boiler wins.
In Kassel the break-even is 0.86 EUR per litre, just under the 2025 average of 0.96. At today's price the heat pump saves 1,571 EUR a year. At the 2025 average it saves 188, about a tenth of the oil bill, and below 0.86 the boiler is cheaper to run.
Installed cost and payback
Nancy: the same job, a heat pump of the 10 kW class with its hot water cylinder, the removal of the old boiler and of the oil tank, costs about 17,800 EUR installed (ADEME campaign figures plus a tank removal price). The typical grant for replacing an oil boiler, MaPrimeRénov' plus the Coup de pouce chauffage, is about 8,510 EUR. That leaves 9,290 EUR, paid back in 5 years at today's oil price and in 14 years at the 2025 average.
Kassel: the same job costs about 36,700 EUR installed (Verbraucherzentrale Rheinland-Pfalz offers without the meter cabinet, plus the tank removal). The KfW grant, 30 percent plus a 16 percent bonus for replacing a working oil boiler, is 12,880 EUR. That leaves 23,820 EUR, paid back in 15 years at today's oil price. At the 2025 average the saving is 188 EUR a year, and the payback takes 127 years.
The same job costs about twice as much in Germany as in France. VAT, 19 percent against 5.5, explains about a fifth of the gap, and the Library article shows what I could and could not source.
The costs and the grants are typical figures from the sources in the Library article, not simulation results. Run your house to see its litres and its running cost, then set your own quote beside them.
What the numbers assume
- The houses: two detached 1990s houses with their original walls, roof, windows and radiators, an unheated cellar and four residents. Rooms are held at 20 °C by day and 17 °C from 22:00 to 06:00. Each site gets one typical weather year.
- The oil boiler: a non-condensing 21 kW boiler with an efficiency of 0.772 on the upper heating value, and a 160-litre hot water cylinder.
- The heat pump: an air-to-water unit sized for the coldest design day, the 10 kW class in Nancy and the 13 kW class in Kassel, with a 200-litre hot water cylinder and an 8 kW backup heater that barely runs.
- Hot water: 2,406 kWh a year drawn at the tap at 42 °C. The cylinder is charged from 05:00 to 06:00 and not restarted before 09:00, so the charge does not collide with the morning heat-up.
- Comfort: both systems stay under the same limit of 300 hours a year with an occupied room below its setpoint. Nancy: 193 hours with oil, 264 with the heat pump. Kassel: 243 and 298.
- Prices: heating oil from the EU Weekly Oil Bulletin, week of 19 October 2026; electricity from Eurostat, first half of 2026.
Run your own house
Your house burns a different amount of oil, and your prices are your own. Enter the house, set your two prices and run it with the heat pump and with your boiler. You get your litres, your electricity and your annual running cost, the way I did here.
The method behind the numbers
The Library article shows how I chose the houses, how the litres follow from the boiler's efficiency, how the heat pump is sized, where the prices come from, where the installed cost and the grants come from, and what the model leaves out.