My Greenstar 28i has been running for about 32 months and has been serviced annually. I have noticed that when using the central heating the pressure gauge is rising when hot but not dropping when cooling down. Yesterday it reached the edge of the red area.

I drained off some fluid from a radiator when it was cool and not running and the gauge dropped to the black line at 1.5 bar but I notice it has risen again today.

Any idea what is causing this problem?

Supermart, December 2009

Thank you for your advice. I was a little doubtful as the filling loop had three valves and they were all off, but followed it anyway and immediately on disconnection the pressure dropped. I bled off some water to return the pressure to 1.5 bar when cold. The pressure rose to 2.0 bar as expected during a four hour heating period but now appears after cooling to have returned to 1.5 bar.

I will continue to monitor it for a few days but my sincere thanks for your advice.

Supermart, December 2009

sounds like the filling loop/or integral link is passing. disconnect the external pipe on the filling loop and make sure no water is getting in. sometimes the filling loop can look turned off but still lets water through

pete, December 2009