My small water tank in my loft keeps filling up. The ball-cock is not leaking, or it does not seen to be filling from the boiler overflow pipe. I think it is filling from an expantion pipe which enters into the bottom of the tank.
If this is part of a gravity hot water system, the tank is there to accept water produced by expansion while the water heats. It is natural for the water level in the tank to rise and fall with temperature, as that is its purpose.
I thank you very much for your quick reply. I am conserned the ball-cock will break under the strain of the rising water. The water rises to the level of the overflow pipe and is warm sometimes hot, causing condensation in the loft. If this is an expantion pipe should the water level also drop and not keep rising.