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Potterton Combi 80 - Pressure?

I have just bled the radiators and refilled the pressure to 1 bar as stated on instructions left by plumber a few years back. Central heating OK but I have watched the pressure creep past 3 bar and into the red. I've turned the heating off as the instructions stated that pressure should be about 2 bar when hot. Any ideas?
Bodge it, December 2007
possible fill loop leaking into system

grahame, December 2007
The reason the pressure is increasing is the expansion vessel located at the back of the boiler is de pressurised.

Release all pressure in the heating system using your drain valve. Lean over the top of the boiler and you will see a red vessel with a valve just like the one on your car. Pump up with a foot pump tp 1 bar or 14lbs pressure. re pressurise your heating with the filling loop Problem solved

John Russell, December 2007
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