Immersion heater replacement in London
An immersion heater is an electric element that screws into the side or the top of a hot water cylinder and heats the water directly, much like a very large kettle element. In some homes it is the backup for when the boiler is off or broken. In others, usually converted flats with no gas, it is the only thing heating the water at all. Ninja Plumbers replaces failed elements and thermostats, and checks both before anybody starts discussing a new cylinder.
- Gas Safe registered and fully insured
- DBS-checked engineers
- Emergency callout available 24/7
- Price agreed before work starts
- Workmanship guaranteed
Monday – Sunday, 7:00 AM – 10:00 PM · Out-of-hours emergency? Call 020 3576 5825
Get a price for immersion heater replacement
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What's included
- Failed immersion heater elements replaced
- Immersion thermostats tested and replaced
- No hot water on a cylinder diagnosed
- Scaled and seized elements removed
- Cylinder drained down and refilled
- Honest view on whether the cylinder itself is worth keeping
Worth knowing first
A bit of this might save you from needing a callout at all — we'd rather you knew it upfront.
What it is, in plain terms
It is an electric heating element sitting inside the cylinder, with its own switch on the wall and its own thermostat. It is wired independently of the boiler, which is why it still works when the heating does not, and why it can fail while everything else in the house is fine.
How to tell it has failed
The clearest sign is no hot water from the immersion while the heating still runs perfectly well. Lukewarm water that never gets properly hot points the same way, as does an immersion switch that trips the electrics as soon as it is turned on. A tripping circuit means the element has broken down internally and should be left switched off until it is looked at.
London water is what usually kills them
Hard water leaves limescale, and an element sitting in it gets caked in the stuff. The scale acts as insulation, so the element works harder, runs hotter and eventually fails. It also makes an old element awkward to remove, because scale and corrosion effectively weld it into the cylinder boss.
Thermostat or element, and a drain-down either way
A failed thermostat and a failed element look identical from the tap, so both get tested rather than guessed at. Replacing the element means draining the cylinder down first and refilling it afterwards, which is the bulk of the time on the job. The connection at the element is electrical work, and our electricians handle that part, so one visit covers both.
Common questions
My heating works but there is no hot water from the immersion. Why?
That combination usually points at the immersion itself rather than the boiler or the cylinder, because the two run on separate circuits. It is most often the element or its thermostat, and both are tested before anything is replaced.
Why does my immersion heater trip the electrics?
An element that trips the circuit when switched on has broken down inside and is letting current where it should not go. Leave it switched off and have it replaced. Do not keep resetting the trip to get one more tank of hot water out of it.
Is it the thermostat or the element?
You cannot tell from the tap — both give you cold or lukewarm water. A thermostat is the cheaper part, so it gets tested first, but on an old scaled element in a hard water area it is frequently both.
Do you do the electrical side of it?
The connection at the element is electrical work and has to be done by someone competent to carry it out. We do both the plumbing and the electrical side, we are fully insured, and our engineers are DBS-checked and directly employed rather than subcontracted. Either way the price is agreed before any work starts.
Part of our heating & hot water work
If it turns out to be a repair job rather than a new install, this is where that's covered.
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Boiler Repair
No heat, no hot water, or a boiler locked out on a fault code. Diagnosed first, then fixed.
More on Boiler Repair -
General Plumbing
Taps, toilets, radiators and pipework. The jobs that never quite get done.
More on General Plumbing
Other appliance work
Need immersion heater replacement in London?
Let us know what’s going on and whereabouts you are, and we’ll give you a price before any work starts.