can any one help....? i have a potterton combi 80 boiler at the moment the ch has to be turned on to get any hot water but when you turn the tap on it's red hot for about 10 secs the go's luke warm also when the ch is on the rads upstairs are hot but the rads downstairs are cold also the pressure on the boiler is on 3 to 3.5 but if i let the pressure off it just goes back up after a while i've checked to make sure the water tap is turned off properly and it seems fine PLEASE can anyone HELP any advice would be greatly appreciated