Immersion Heater vs Boiler UK: Which Is Cheaper to Run?
Immersion heaters use electricity to heat stored water; boilers typically use gas, LPG, or oil. This UK guide compares running costs, practical efficiency, and which setup suits typical homes in 2026.
How Each Works
Immersion elements heat a cylinder directly. Boilers heat water via a heat exchanger and may also run radiators.
Running Costs
Electricity per kWh is often higher than gas on many UK tariffs—direct electric water heating can be costly unless you have favourable rates or solar usage patterns.
Comfort and Flow
Combi boilers can deliver strong tap flow when mains and model allow. Cylinders suit high simultaneous demand when sized and controlled well.
What Makes Sense?
Many homes use a boiler for primary hot water with immersion as backup. Off-gas homes may use heat pump cylinders or electric strategies.
Get the Right Boiler Size for Your Home
Our free boiler size calculator uses your property details, radiator count, insulation and hot water needs to recommend a suitable kW range. No sign-up required—get results in seconds.
Use the Boiler Size CalculatorFrequently Asked Questions
Is immersion cheaper than gas?
Usually not on running costs where mains gas is available—tariffs matter.
Can I use immersion and boiler together?
Yes—common for backup or solar diversion setups.
Should I leave immersion on 24/7?
Usually wasteful—use timers.
Is immersion efficient?
Resistance heating is efficient at the element, but grid cost per kWh can be high.
What about heat pumps?
Heat pumps often use cylinders; economics differ from immersion-only systems.