No Hot Water from an Immersion Heater

Key checks

When to call an engineer

If the problem involves fixed wiring, high-current heating equipment, repeated tripping, unvented hot water or uncertainty about the supply arrangement, testing is safer and usually faster than swapping parts.

Related specialist pages

Boost works but overnight hot water does not

On a dual-immersion Economy 7 cylinder, that pattern often points away from the cylinder shell and towards the off-peak side: the lower element, thermostat, fused connection, switched circuit, contactor or tariff-controlled supply. Testing needs to follow the circuit rather than replacing both elements automatically.

RCD trips when the immersion heats

A damaged immersion element can develop leakage to earth as it heats. The correct diagnosis uses appropriate electrical testing and checks the flex, terminals and control at the same time. Continually resetting a protective device is not a repair.

When replacement is justified

If the cylinder is leaking, heavily corroded, unsuitable for the household demand or the repair cost is poor value relative to a new correctly sized system, replacement may be the better route. Otherwise an element or thermostat repair can be much more economical.