pressure raising when system cold

[lynx2]

Hi
I have a potterton combi boiler, which works fine but the pressure seems to raise when system is off, it is chraged to 1 bar but raises. I have checked the filling loop which is ok, checked the flexi hoses on the CH expansion vessel its ok to.
Any suggestions Thanx!!

 

[gazthepottertonengineer]

Is your filling loop letting bye check by disconnecting the hose

 

[ollski]

Hole in the hot water heat exchanger?, how long does it take for the pressure to climb?

 

[lynx2]

it takes about 3 hours to climlb 1bar.

 

[weareleeds]

Depending on blr make & model but suspect either main or plate heat exchanger