You likely have an immersion heater if you have a hot‑water cylinder (tank) with an electric heating element fitted into it, usually controlled by its own switch or fused spur on the wall.

What an immersion heater looks like

• It is an electric element that screws into the side or top of a hot‑water cylinder, usually brass or copper with a small rectangular or round plastic cover where the wires go in.

• The cylinder is typically a tall, insulated metal tank (often in an airing cupboard, loft, or utility room), sometimes labelled “hot water cylinder” or “immersion”.

Easy checks you can do

• Look for a separate wall switch or fused spur near the cylinder, often labelled “Immersion”, “Water heater”, or showing a little cylinder icon.

• Open the airing‑cupboard or wherever your hot‑water tank is: if you see an electric cable running to a capped boss on the cylinder with a plastic cover, that is almost certainly an immersion heater.

If you only have a combi boiler

• If your home has a combination (combi) boiler and no separate hot‑water cylinder anywhere, you almost certainly do not have an immersion heater, because combi boilers heat water on demand.

• If you are unsure what type of boiler you have, a heating engineer or electrician can confirm and also identify any immersion heaters safely.

Safety tips

• Do not remove covers or touch wiring unless you are competent and the power is fully switched off at the isolation switch and consumer unit.

• If something looks damaged, corroded, or gets very hot or smells, stop using the heater and call a qualified electrician or heating engineer.