Hi, I have read posts similar to this but can't seem to find one where this problem happens all the time whether the central heating and water is on or off. Even when the boiler and water are cold I can hear water hissing in the pipes running to the small tank but because of the design I can't actually reach the f/e tank to see the level or change the ball valve. I have 3 black water tanks on a shelf at the top of the airing cupboard above the hot water cylinder and controls - the f/e tank is tucked into the left hand corner with not a lot of room to manoeuvre. I suspect all the tanks will have to come out to fix this but if you can suggest something that would help me avoid this then I would be very grateful. There is a red wheel type tap/valve in one of the vertical pipes at the back of the cupboard so would it have something to do with that?
Looking forward to your replies, many thanks.