APPLIANCE RUNNING COSTS · OCT–DEC 2026
How much does an immersion heater cost to run?
Most immersion heater elements are rated at 3 kW, so an hour of heating uses about 3 kWh. At the GB average price-cap electricity rate of 26.32p per kWh for October–December 2026, an immersion heater costs about 79p an hour at full power, or 79p for a typical 1-hour day.
PER HOUR
79pat 3,000 W, full powerPER DAY
79p3.00 kWh over 1 hourPER WEEK
£5.537 days a week (assumed)PER YEAR
£2881,095 kWh at the assumed useWork out your own cost
Choose your region or type in your own unit rate, then change the wattage and hours to match your appliance and how you use it. It starts with a week at our assumed use, averaged to hours a day.
21 kWh over 7 days · about £0.79 a day
How much electricity it uses
- Heatrae Sadia’s Megaflo Eco Direct cylinders use 3 kW immersion elements (2.8 kW at 230 V); larger cylinders have two.
- A well-insulated cylinder still loses some heat: Heatrae Sadia quotes standing losses of 0.91 to 1.69 kWh a day for its 70 to 300 litre models.
- The thermostat switches the element off when the water reaches the set temperature, so it does not run at full power for as long as it is switched on.
| Example | Rated power | Per hour | Per day | Per year |
|---|---|---|---|---|
| Lower | 2,800 W | 74p | 74p | £269 |
| Typical | 3,000 W | 79p | 79p | £288 |
Usage assumption: One hour of heating a day at full power. Real use depends on how much hot water you use and the cylinder. This is our illustration, not a measured average; change it in the calculator.
What drives the cost
- How much hot water you use.
- Thermostat setting and cylinder insulation.
- Leaving it on all day rather than on a timer.
How it compares
| Appliance | Typical use | Energy | Cost |
|---|---|---|---|
| Immersion heater | 1 day, 1 hour | 3.00 kWh | 79p |
| Electric shower | 1 shower, 7.5 minutes | 1.19 kWh | 31p |
| Kettle | 1 boil, 2 minutes | 0.10 kWh | 2.6p |
Ways to spend less
- The Energy Saving Trust recommends setting the hot water cylinder thermostat to 60°C: hot enough to kill harmful bacteria.
- It also says topping up a thin cylinder jacket with an 80 mm British Standard jacket could save about £45 a year in Great Britain.
Unit rates vary by region: this period they run from 25.36p per kWh in East Midlands to 27.86p in Merseyside and Northern Wales. See every region’s rate →
Questions
How much does an immersion heater cost to run per hour?
At 26.32p per kWh (the GB average price-cap rate, October–December 2026, Direct Debit, 0% VAT), an immersion heater rated at 3,000 W costs about 79p an hour at full power. Models from 2,800 W to 3,000 W cost 74p to 79p an hour.
How much does an immersion heater cost to run a year?
It depends on how much you use it. Our assumption is one hour of heating a day at full power. Real use depends on how much hot water you use and the cylinder. At 26.32p per kWh that comes to about £288 a year (1,095 kWh). Change the hours or uses in the calculator to match your own.
Should I leave my immersion heater on all the time?
With a thermostat it will not run constantly, but the cylinder keeps losing heat, which the element then replaces. A timer that heats water shortly before you need it usually uses less.
Does the cost depend on where I live?
Yes, a little. Price-cap electricity unit rates for October–December 2026 range from 25.36p per kWh in East Midlands to 27.86p in Merseyside and Northern Wales. Pick your region in the calculator, or enter the unit rate from your bill if you are on a fixed or time-of-use tariff.
About these figures
Running costs are energy used × unit rate. They exclude the daily standing charge, which you pay whether or not the appliance runs. Costs per hour assume the appliance draws its full rated power the whole time; many appliances cycle on and off, so real use is often lower. Power ratings and energy figures are examples from the sources below, not a measured UK average.
Other appliances
Sources
- Heatrae Sadia Megaflo Eco Direct technical data sheet (PDF) ↗Immersion heater rating 3 kW at 240 V (2.8 kW at 230 V); standing heat loss 0.91–1.69 kWh per 24 hours for 70–300 litre cylinders.
- Energy Saving Trust: heating controls ↗Hot water cylinder thermostat setting (60°C).
- Energy Saving Trust: quick tips to save energy at home ↗Savings tips for kettles, washing machines, dishwashers, drying and standby (page last updated 6 October 2026).
- Ofgem: energy price cap unit rates and standing charges ↗GB average electricity unit rate and VAT basis, October–December 2026.
Last updated 11 October 2026. Figures are dated benchmarks taken from the sources above. How we use sources →