DIY Doctor UK DIY Forums

My cold water header tank is occasionally overflowing.I have switched off the c/h boiler and the cold feed to both the cold water tank and the c/h tank.
Warm water is rising into the cold tank and pushing the water level up,so that it overflows.
Previous similar queries have laid the blame on leaking coils inside the hot water tank.
In my case I can`t understand how water is being pushed up above the level in the cold tank as the c/h tank is about 700mm below that level!
Can anybody suggest how and a possible fix please?

Hi Reggie,
1. Have you checked the ball valve is shutting off and that it is free to move up and down. Is the ball float sound? ie no water in it.
2. Do you have any taps fed by mains cold and tank fed hot that are of mono block design. There may be a fissure in the body.
Regards S

Thanks for the reply.
It turned out to be your second suggestion.The cartridge to the monobloc bathroom basin tap had fractured and was allowing mains pressure water to push into the low pressure hot water system.It was only occuring when the cold water had been used ,and even then only at certain times.This has been a perplexing problem,but now sorted thanks to your help.
Many thanks!!!

Hi Reggie,
Glad it’s sorted, thanks for letting us know the outcome.
Regards S