i have a potterton compact combi boiler installed in my property which is having pressure problems, the low pressure warning light is permantly flashing on the pressure gauge the red pointer is set at 1.5 bar, the black pressure pointer either goes down to zero and i have to top up by opening the filling loop valve to 0.7 bar, or the pointer goes the opposite way and goes a little bit above the red pointer. is this a fault with the pressure relief valve, the boiler is also quiet noisy in use its about a year old and was fitted by the previous owner. i would be grateful for any suggestions.