Potterton combi 100 water pressure

[joker1981]

Hi, I have a potterton combi 100 boiler.

I have checked the pressure and it was set at 1.5 when cold (boiler not running) but this shot up to about 3.5 (into the red on dial) after about 1/2 hour of running central heating.

There is an intermittent whistling noise coming from the boiler both from when CH and HW are being used and my radiators are red hot even though the thermostatic valves are only half open.

I have bled the radiators and even let some water out of them via the bleed taps. the pressure seems to drop back down fairly quickly when the boiler is switched off.

any help or advice please

thanks

 

[Agile]

Look up expansion vessel in the FAQs on this site.

Its either failed or it needs repressurising.

Tony