Hot Water Cylinder

22 Jun 2008
Reaction score
United Kingdom
The electrical immersion trips when switched on. The wiring seems OK. The cylinder is warmed by the cental heating boiler as well. It is an old cylinder (20 years old). I want to change the immersion heater on the top of the cylinder. What pitfalls lie in wait? Do I need to drain the cylinder?
I would be grateful for any guidance
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try slacken the element slightley before draining then when loose drain enough to remove element
But not before you turn off water supply to tank or you'll get very wet!
Worst thing you can do is cause a split in the cylinder around the immersion heater, but this is usually only likely to happen on cylinders which rely on immersion heaters and have had them replaced several times as it weakens the copper.
To drain down all you need to do is close the gate valve feeding the cold water into the cylinder.This is usually at back of airing cupboard and should be positioned above the height of the cylinder.
And then open the hot taps in the house . These will stop running after about 10 seconds.
I usually just undo connection on top of cylinder that supplies hw and drain off the first 6 inches of water,then remove old immersion and just put it all back together.
Easy job , if you are confident and capable.
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soon you won't need any plumbers just come on here and get the answers FREE.
Why do you want to use the immersion . If your gas CH system is a fully pumped modern system with a cylinder stat then this is cheaper than using electricity to heat the water.
Agreed, she never uses it, but still wants a back up, "just in case", and I am happy to add to my limited knowledge of plumbing!

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