Overflows

[Wenderline]

What causes the overflow pipe to leak only when the heating comes on

[naz_nomad]

expansion, caused by heating the water, i should think

[dilligaf]

I have the same problem which I hope to resolve tomorrow. I was told the expansion tank is too full. Either a leaking or badly adjusted ball valve. I was been told the valve should shut as soon as the ball starts floating unlike a toilet cistern when it shuts off almost at the top.
This is only what I have been told. Good luck

[sarah_louise]

Yes check the expansion tank float valve it could be faulty or corroded up.

[buildersmate]

I reckon its a combination of all the 3 answers above. Expnasion when the heating first comes on causes a minor backflow of water back up to the small tank, and because the ball-valve level is set really close to the top of the tank just below the overflow pipe level, its enough to allow a bit of water out. Do as Dillagaf suggests.

[tezestwing]

Hi Wenderline BM I think you meant do as Sarah, dilligaf didn't suggest anything realy, but I would just like to add that it is important to deal with a faulty ball valve, loss of water issues or dried up expansion tank.HTH Tez