How sure are you? What’s your heating circuit? Gravity (little tank in the loft) or pressurised (need to top up the pressure with the filling loop)?
It could be a mains water connected tap/shower letting by and back filling the cylinder/tank.
If you’re heating system is gravity, that won’t be back filling (no pressure).
If it’s pressurised, dump the pressure in the heating system to see if it stops back filling.
If it doesn’t, a second test is to shut off the mains to the house and open the kitchen tap to drain the mains pressure from your system. If it stops back filling something is letting mains in.
Fairly certain that it’s the cylinder because we had a friend ( engineer) around who did a repiping job near the cylinder ( due to a blockage) , so We are pretty certain that’s it’s the cylinder and need a new one if that’s possible.
The system is two tanks in the loft , 1 big one ( cold water tank ) and a smaller expansion tank about 4 foot away . Both float valves / ball cocks working correctly ( in fact changed the big tank ball ) .
So awaiting our ch engineer decision on whether to change cylinder of scrap the whole system ( unfortunate because it’s works brilliantly after re pipe , aside the leak )
Engineer has some unfortunate family problems so we have to be patient with the poor lad and naturally don’t want to mither him or indeed ask someone else.
So I’ll keep lowering the level in the expansion tank in the loft ( bit tricky cos I’ve recently had a hip replacement) to stop the leak, I know it’s sounds like a comedy sketch with respect .
So would like to know will switching off mains stop the overflow?
Does or will using the CH make the problem worse ?
Is there a a way just to stop the water supply to the cylinder temporarily?
Or a way of drawing the lowering the level in expansion tank without doing it manually.
Btw it is a 40 year old system that’s served us well and still is without the overflow drip , so not moaning.
cheers for any responses.
