leebex

Ive got a question regarding my central heating/hot water system Im hoping someone can help with.

The system in my house has a small gas boiler in the kitchen, an airing cupboard upstairs, with hot water tank, and the small gravity feed tank in the loft above that.

At the moment we only have the system making hot water, the rads and thermostat are set to off.

every evening a couple of hours after the timer has gone off, about now 8pm, I get a flow of water come out the overflow from the gravity tank, probably a couple of cup fulls.

the float in the tank is fine, and that tap isnt putting in unwanted water, but the other day i watched the pipe into the top of the tank flow water into the tank (this isnt the one with the float)

Whats the likely cause for the system to be putting too much water into the gravity tank and is this coming from the heating system, im guessing its some kind of return?

Thanks, Lee