Leaking vent pipe

[Gaskell]

I have a New World behind the fire central heating boiler which is quite old but works OK. Problem is, hot water is continually being pushed up the expansion pipe and into the expansion tank and from there out through the overflow pipe. Any Ideas for a solution?

 

[bripl]

sounds like boiler stat has failed.get a competent engineer to repair/diagnose.

 

[TexMex]

Reallly need more info on this. Does it do it, just when there is demand for Hot water, or Central Heating or both? I presume that, since it's quite old, this is a new problem? Has anything been changed recently?

Have you ruled out the float valve in the H&E tank. It could just need adjusting. If it's keeping the level too high, when it gets warm through use there is not enough space for expansion. It could even be letting water by.

It may just be a matter of sludge build up in the plumbing. When the pump tries to circulate the water it causes excess pressure that has nowhere else to go.

 

[Gaskell]

Thanks Bripl, Boiler stat checked and OK.

Thanks TexMex, expansion tank valve OK, just replaced and isn't leaking. Could be set too high though. Will adjust it and see. Pipe leaks both on Hot water priority and Heating priority. Sludge in system could be the answer, am in very hard water area.

 

[ChrisR]

If your system is gaining water and the inlet valve isn't leaking (like, turn it off, heh? ?) then it will be coming from a leak in your hot water cylinder between the boiler water and the tap water. Only if the level in the cold cistern is above the level of the f&e tank of course, which it should be. IN which case you need a new cylinder.

 

[Gaskell]

Hey ChrisR, that sounds like a possibility worth investigation. Thanks.