Immersion heaters

Immersion heaters use an electrical heating coil in a tank of hot water for your supply. They could be for use “on demand” with an on/off switch or use a timer. Either way, you’ll want to try to only heat the water you need and make sure they aren’t left on permanently. Read our advice about hot water cylinders as immersions are similar, and think about the controls.

• Hot water cylinders

• Timeswitches and countdown timers

Sometimes buildings have both an immersion and a tank supplied by a gas boiler that is mostly for heating. Sometimes this is just in case the boiler breaks down, but depending on the boiler and the immersion, it can be more efficient to switch to the immersion in the summer when the heating is off.