Expansion vessel recharge question

[zebedee2001]

Hi all, I thought I would check the expansion vessel pressure on my sealed heating system. I put a tyre gauge on the vale and no air came out. If I use a pump to inflate the pressure vessel the boiler pressure goes up but I still can't get any pressure reading from the valve. I don't get any pressure out of it if I push a screwdriver into the centre of the valve

However, I noticed that the rear red nut was loose. If I lose it more then push the whole valve in air rushes out. Any ideas how I can pump this up to a known pressure or do I need to replace the vessel?

Thanks for looking and would appreciate any help on this one

 

[Servotech]

You need to have an open end to push the water out whilst you pump the air into the vessel - you can compress air but not a liquid.
Get someone to hold the PRV open whilst you pump the air in is probably the less messy way of doing this but it's not the best way.

 

[ianmcd]

you need to open a drain point as you pump the vessel up, if no water comes out of the drain point as you attempt to pump it up you have a blocked communication hose/pipe

 

[Johntheo5]

The boiler pressure goes up when the air end is pumped up so why doesn't any air come out of the schrader valve assuming the inside is being depressed?

 

[ianmcd]

The boiler pressure goes up when the air end is pumped up so why doesn't any air come out of the schrader valve assuming the inside is being depressed?

Boiler pressure should never alter AS YOU NEED A DRAIN POINT OPEN WHEN PRESSURISING THE VESSEL, no there is no other way there is no shortcut YOU NEED A DRAIN POINT OPEN the water has to go somewhere

 

[Johntheo5]

Did you read my post correctly?, I merely said that "The boiler pressure goes up when the air end is pumped up so why doesn't any air come out of the schrader valve assuming the inside is being depressed?" I was not commenting on the correct/incorrect method of re charging a E.vessel.