Sorry haven't got clue had a txt from sister inlaw while in work about her shower, but obviously i've given you as much information as she's given me(nothing).
Thanks anyway
James
I have a central heating boiler with hot water tank an two cold water tanks in loft.
The water in the hot water tank is pushing up into cold water tank an obviously making it overflow. I know this because when the hot water has been on the water is warm in the loft. It overflows continously...