Overflow problem - can anyone help

[harris48]

I have a problem with my overflow, it seems when i switch the heating on the overflow seems to pour out (not all the time but in spirts rom the loft).

We have a gravity fed system - with the cylinder on the first floor and head tanks in the loft. I've tried changing the washers, but this has no affect, also tried altering the arm on the ball valve again with little affect. The overflow is from the cold staorage tank(s) not the feed and expansion tank.

Can anyone provide any alternatives as what could be wrong - your advice would be most appreciated.

 

[ollski]

It depends, if the f&e tank is higher than the storage tank then it could be a split coil in the cylinder, but first check would be your mixer taps. If the hot and cold in the mixer are somehow mixing together then the mains cold will force its way up the hot water pipe and back fill the storage tank.

They are the alternatives, but first replace the complete ball valve.