I have gas central heating with the boiler in my upstairs bedroom. Being very cold last night I left the heating on & opened the hatch to the loft also. This morning I have cold water downstairs but no cold water in the bathroom upstairs, toilet cannot flush either. The house is 22 years old & terraced so heat from either side too.

Marilyn Muir, January 2010

A neighbour advised that the heat would rise & help the temperature in the loft. Hence reason for leaving loft hatch open. Getting knee replacement op next week so can't hop up there myself...yet!
I've seen 2 black boxes. Should I buy special lagging? I take it the ballcock you mention lies at the top of the small tank?

Many thanks indeed for taking the time to reply. Very much appreciated!

Marilyn Muir, January 2010

puzzled why you left the loft hatch open
am assuming you have 1 or 2 cold water tanks up there, the little one probably feeds the central heating ,the other cold water storage device if not lagged they will freeze check the ball valve is not stuck/frozen
the ice will then hold the ballcock up till the ice melts away from the side of the tank allowing the whole slab of ice to drop now allowing water flow
the wind can blow up the overflow pipe and freeze, (the contents of the tank this can be prevented by fitting of a tee piece on the end of overflow pipe)

wirecutterman, January 2010