when the boiler is off on my potterton puma 80 the pressure drops to 0 bar,and when left on for 1 hr or so the needle jumps into the red zone 3 bar.what can i do or replace to fix the problem.thanks
sounds like the expansion vessel is faulty. need to check pressure of vessel (same method as for car trye)if when you do this it is full of water new vessel is required
