On Feb 10, 2:32*pm, "Vortex4" wrote:
wrote in message

...

hi there
I have a pressure prob with a sealed gfch system.

The pressure shoots up and down - according to the FAQ, this prob
means that the expansion chamber has failed, but when I check the
chamber, there is no water coming out of the valve - only air. Air
pressure is approx 10/11 PSI. I keep topping up water, but there is no
apparent leak...

Any ideas?

Is is a combi boiler or do you have a separate DHW tank?

If the latter there could be a leak of primary water from the tank coil into
your hot water system.

Its a combi, Potterton Puma 80 boiler.