Promax rapid rise in pressure when on

[AirCoolFool]

Hi.
I have a Potterton Promax Combi HE +

When the heating comes on the pressure rises over a few minutes until the safety valve blows off the extra pressure.

If I manually release the pressure to 2bar it then pretty much stabilises and stays there. However once the system goes off and it cools the pressure drops and E1 is displayed.

I have let the pressure out the expansion vessel to check there is not water coming out the valve to show it is ruptured internally, then repressurised it and this hasn't changed it?

Any advice as to what could be up? From what I've read I'm looking at replacing the Pressure Vessel or draining the vessel down and starting over?

Thanks for your help folks.

 

[terryplumb]

The EV needs to be correctly pressurised , if its still a problem it will need replacing. Did you DE PRESSURISE the boiler / system side of the EV before charging it with air ?

 

[ianmcd]

as already advised you have not re-pressurised the expansion vessel properly, it has to be done following every step correctly or no point in doing it at all, there are hundreds of posts on here telling you what to do

 

[AirCoolFool]

Hi, thanks for the replies.
I let all the pressure put the boiler side by turning the pressure relief valve knob and checked the dial read zero on tye front of the boiler. Then I pressurised the pressure vessel with a pump to the pressure on the side of it and then the system via the fill loop.

This is what has me perplexed.

 

[ianmcd]

one you should not use the PRV it will probably start dripping now, two you MUST leave an open drain point on the boiler or system as you repressurise to push all the water out of the vessel, then once all the water is out of the vessel then you can start to repressurise the bladder then when at 0.8 Bar remove the pump, close the drain valve and then fill the system with water to between 1 and 1.5 Bar, there is NO other way to do it if you dont follow ALL of these steps there is no point

 

[ianmcd]

your boiler has an inbuilt designated drain point that should be used

 

[AirCoolFool]

Ok. Thanks again. I'll give that a shot.

 

[AirCoolFool]

Ian, how do I tell all the water is out the vessel?

 

[nwgs]

Ian, how do I tell all the water is out the vessel?

When your pumping it up water will stop coming out of the drain when it’s empty

 

[ianmcd]

When your pumping it up water will stop coming out of the drain when it’s empty

as @nwgs says once the water stops coming out the vessel is now empty and ready to be pressurised, you will be surprised how much water you need to pump out it can be up to 8L at times