Heating 135 L a day costs 812 €/yr with your electric storage tank. Cheapest to run: heat-pump water heater (284 €/yr). Lowest cost including purchase: gas tankless / combi.
Running cost: Electric storage tank
€812
3,250 kWh of electricity per year
Useful hot-water heat
2,710kWh/yr
7.4 kWh/day for 135 L at ΔT 43 K
Cheapest to run
€284
Heat-pump water heater
Possible saving
€528
per year vs your current heater
Lowest total cost
€408
Gas tankless / combi incl. purchase ÷ lifetime
Standby losses (tank)
€121
of your current heater, per year
CO₂ per year (current)
1.14t
lowest: Heat-pump water heater
Instant heater power for a shower
17.6kW
9 L/min at 40 °C, which is why electric tankless needs a big supply
Cost per shower
€0.58
35 L of hot water
All six technologies
| Type | Energy (kWh/yr) | Running (€/yr) | Installed (€) | Life (yrs) | Total (€/yr) | CO₂ (kg/yr) |
|---|---|---|---|---|---|---|
| Gas tankless / combi | 3,080 | 308 | 2,000 | 20 | 408 | 564 |
| Heat-pump water heater | 1,137 | 284 | 2,800 | 13 | 500 | 398 |
| Gas storage tank | 4,387 | 439 | 1,300 | 11 | 557 | 803 |
| Solar thermal + electric backup | 1,528 | 382 | 5,500 | 20 | 657 | 535 |
| Electric tankless (instant) | 2,737 | 684 | 900 | 20 | 729 | 958 |
| Electric storage tank | 3,250 | 812 | 700 | 12 | 871 | 1,137 |
- Heat = litres × 4.186 kJ/kg·K × ΔT. Tank heaters add standby losses; the heat-pump heater covers both at its COP. Solar thermal assumes a 30% larger tank and electric top-up.
- Total cost spreads the installed price evenly over the typical lifetime (no interest). Gas heaters assume an existing gas connection.