Replacing an immersion heater element
Check the steps below first — if you're not confident, get it fixed safely today.
Post a job — we'll find you an engineer →⚠️ Always isolate the electrical supply at the consumer unit before working on an immersion heater.
An immersion heater is one of the most reliable ways to heat water in a UK home, but when it stops working, you're left with cold water and frustration. The good news is that nine times out of ten, the problem isn't the element itself — it's something much simpler that you can check in seconds. Most immersion heater failures happen gradually (the water takes longer to heat) or suddenly (no heat at all), and they're surprisingly common in homes where the heating system relies on electricity rather than a boiler. This guide walks you through the quick checks that solve the problem in minutes, and explains when you genuinely need to call in a professional. If basic troubleshooting doesn't work, you'll need an electrician or qualified plumber, as replacing the element safely requires isolating the electrics and draining the cylinder.
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Most likely cause & what to check
Before assuming the element has failed, check the basics: is the red immersion heater switch turned on? Has the thermostat reset button (small red button on top of the element) tripped? Press it firmly to reset.
If those checks don't help, the element itself has likely failed and needs replacing. This involves draining the cylinder and working with electricity — not a DIY job for most people.
Call an electrician or plumber who handles immersion heaters. Tell them: "My immersion heater isn't heating — I've reset the thermostat button but it's still not working."
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Frequently asked questions
How do I know if my immersion heater element has actually failed?
A failed element won't heat the water at all, even after you've checked the switch and reset the thermostat button. If the water is lukewarm or heating slowly, it's often a thermostat issue rather than element failure. The only way to confirm is to have an electrician test it with a multimeter.
Why does the thermostat reset button keep tripping on my immersion heater?
The thermostat button trips when the water gets too hot, which is a safety feature. If it's tripping repeatedly, the thermostat itself may be faulty and not switching off at the right temperature. This should be checked by a qualified electrician, as it's a potential safety issue.
Can I replace an immersion heater element myself?
Technically you can access the element (it's usually a large bolt on the side or top of the cylinder), but it's not recommended for DIY unless you're confident working with electrics. You'll need to drain the cylinder, isolate the power at the consumer unit, and ensure the element is compatible with your cylinder — any mistakes could be costly or dangerous.
How much does it cost to replace an immersion heater element?
A replacement element itself costs between £20 and £60 depending on wattage and type, but labour charges from a plumber or electrician typically range from £100 to £200 plus the cost of the part. Getting quotes from two or three local tradespeople is always sensible before committing.