Immersion heater not working? Here’s what to do

What is an immersion heater?

An immersion heater is an electric heating element installed inside your hot water tank. It works by heating the water directly, acting either as a primary heat source or as a backup to your main heating system.

They’re commonly found in homes without a gas supply or used alongside boilers to provide hot water independently. Because they rely on electricity and internal components, there are several reasons why they may stop working over time.

Common immersion heater problems

If your immersion heater isn’t working, it’s usually due to one of the following issues.

Limescale buildup

Over time, limescale can build up around the heating element, especially in hard water areas. This acts as an insulating layer, making it harder for the element to heat the water effectively.

If your water is only getting lukewarm or taking much longer to heat, limescale could be the cause. Regular descaling or installing a water softener in your home can help prevent this buildup, but if it is severe, the element in your immersion heater may need to be replaced.

Faulty wiring

Loose connections or damaged wiring can prevent electricity from reaching the immersion heater, which can result in the system not heating at all.

This isn’t something you should attempt to fix yourself. If you suspect a wiring issue, it’s best to contact a qualified electrician who can safely diagnose and repair the fault.

Thermostat error

The thermostat controls the temperature of the water inside your tank. If it becomes faulty, it may stop heating the water altogether or fail to regulate temperature properly.

In some cases, the thermostat may have a safety cut-out that has tripped. Resetting it could restore functionality, but if the issue persists, the thermostat may need to be replaced.

A tripped circuit breaker

If your immersion heater has suddenly stopped working, it could be due to a tripped circuit breaker in your fuse box (consumer unit).

Check your fuse box to see if any switches have been triggered. If so, resetting the breaker may restore power. However, if it trips again, this could indicate a deeper electrical fault that requires professional attention.

Failed heating element

The heating element inside the tank can burn out over time, particularly in older systems. If this happens, your immersion heater will stop heating water completely.

This is one of the more common faults and usually requires the element to be replaced by a qualified engineer.

Insufficient water pressure

Low water pressure can affect how efficiently your system operates and may impact the heating process.

If you’re experiencing both low pressure and poor heating performance, it’s worth checking your wider plumbing system or contacting a professional for advice.

Problems with the insulation

Insulation plays an important role in keeping water hot inside your tank. If the insulation has degraded or become damaged, heat may escape too quickly, making it seem like the heater isn’t working properly.

In this case, improving or replacing insulation can help restore performance and efficiency.

Immersion heater maintenance tips

Regular maintenance can help prevent many of these issues and keep your immersion heater working efficiently for longer:

• Descale the system or install a limescale filter in hard water areas
• Check for signs of corrosion or wear on the tank and components
• Ensure electrical safety by having wiring checked periodically

Keeping on top of maintenance not only helps prevent breakdowns but can also extend the lifespan of your system.

Keep your immersion heater protected with HomeServe Boiler and Central Heating cover

Prepare for future immersion heater faults with HomeServe.

With our Boiler and Central Heating cover, you’ll have access to qualified engineers who can diagnose and repair faults quickly and safely. Whether it’s a faulty thermostat or a problem with the heating element, we’ll help get your hot water back up and running with minimal disruption.