Cold water cistern overflows when hot water is on. All aspects of plumbing questions and answers, help, tips and information

[Stevie-78]

Hi, My cold water cistern in the roof constantly overflows when the hot water is on. When I take the top off I can see hot water entering at the bottom from the pipe which should feed cold water to the bottom of the hot water cylinder. I have an in-direct two circuit system and when the hot water is on all four pipes to the hot water cylinder feel hot to touch. It's like there's too much hot water being produced, which is escaping back through both of the cold water feeds. Any ideas on what the problem is and how I fix it?
Thanks, Stevie-78

[stoneyboy]

Stevie-78,
Chances are that the heating coil in the hot water cylinder is failing. When the heating is on this creates pressure in the coil which then feeds into the cylinder.
You probably need specialist help to identify the problem.
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