How should I check what's wrong with my Immersion Heater?

Fact checked by engineering and technical team members Ryan Kelly and Jamie Hoole

The following article will explain to you how to check for faults or issues with your Immersion Heater. For additional information on how to change the immersion heater, please visit our How To guide.

There is no electricity supply to the Immersion Heater

Check if an electrical current is going to the heater. The circuit breaker may have tripped.

The over temperature trip in your Immersion Heater’s thermostat has cut out

There should be a small button on the thermostat which may have tripped. Push this back in place to reset the cut out.

The thermostat in your Immersion Heater is faulty

Carry out a resistance check across the element terminals. If the resistances are correct, there may be a thermostat issue.

The Immersion Heater has failed to earth

Insulation breakdown is a common fault causing current to flow from live to earth in the element. This can create the following problems:

• RCD will trip if its on a protected power feed
• Current flow is often increased, which can blow fuses, MCB tripping or burnt accessories
• A tripping MCB may prevent it starting. This fault can be detected by measuring resistance between the element connections and its casing. This should be less than 1 ohm

The Immersion Heater has gone open circuit

Perform a resistance test across terminals. If resistance is infinite, the unit has gone open circuit, and the Immersion Heater will need to be replaced.