How Much Does It Cost to Run a Immersion Heater? (UK 2026)
Based on the active UK Ofgem price cap of 24.5p per kWh (1 January 2026 – 31 March 2026).
A typical 3000W immersion heater costs £0.73 per hour of continuous use at current UK electricity rates (24.5p/kWh). For typical daily usage (2 hours daily on Economy 7 / off-peak timer to recharge hot water cylinder (~6.0 kWh/day)), it costs approximately £1.47 per day or £535.08 per year.
Manufacturer specs: Megaflo & Santee standard 3 kW domestic unvented hot water cylinder immersion element
How to Save Money Running a Immersion Heater
- Fit a 7-day mechanical or electronic timer so the immersion only runs during off-peak overnight tariff hours (Economy 7).
- Insulate the hot water cylinder with a 80mm British Standard jacket and insulate all exposed hot water pipework.
- Set the tank thermostat to 60°C; this is hot enough to prevent Legionella bacteria while preventing unnecessary scald-level heating.
- Never leave an immersion heater switched on 24/7; doing so can cost over £100 a month in standby heat loss.
Alternative Appliances Compared
vs. Electric Shower
View running cost →An electric shower heats only what you use, avoiding having to maintain 150–200 litres of standing hot water in a cylinder.
vs. Electric Kettle
View running cost →If you only need hot water for washing up a single pan, boiling a kettle is far cheaper than heating an entire 200L tank.
Immersion Heater Technical Power Profile
Source data: Megaflo & Santee standard 3 kW domestic unvented hot water cylinder immersion element
Frequently Asked Questions: Immersion Heater Electricity Costs
How much does it cost to run a 3kW immersion heater for 2 hours in the UK?â–¾
A 3000W immersion heater running for 2 hours consumes 6.0 kWh. At the standard 24.5p/kWh price cap, that costs approx. £1.47 per day (£44.10 per month).
How much does leaving an immersion heater on all day cost?â–¾
Leaving an immersion heater on 24/7 with thermostat cycling consumes around 12 to 18 kWh per day, costing between £90 and £135 per month in the UK.
What is the ideal immersion heater thermostat temperature?â–¾
60°C (140°F). Temperatures below 60°C pose a risk for Legionella bacterial growth, while settings above 60°C waste electricity and accelerate limescale buildup.
Can a cylinder jacket reduce immersion heating costs?â–¾
Fitting a thick 80mm British Standard insulating jacket to an uninsulated hot water cylinder saves around £50 to £70 per year in heat losses.
Can solar panels power an immersion heater?â–¾
Yes. Installing a "solar diverter" (like an eddi or myenergi unit) automatically routes surplus rooftop solar generation into the immersion heater for free hot water.