how do you recharge a expansion vessel

[sav]

how do u know when you have the right pressure ect?

 

[moony]

it'll be 0.5, 1 or 1.5 initial charge pressure, go to manufacturers instructions and always be charged higher than the static pressure of the heating.

 

[WHPES]

Use an accurate pressure gauge - some of the ones on the car pumps have too large a scale.

 

[jono44]

Hi Mate,
First push the pin on the schrader valve to make sure no water comes out (water means failed diaphram) air is good.
To check expansion vessel for correct pressure on the system you need to make sure that all of the pressure is relieved from system first (drain down)
Next use a pressure guage to check what you have at the schrader valve and if its nothing you need to pump it up to about .75 bar or whatever the MI states and also
as q-plumb says. If ti is nothing (0bar) it could be a leaking valve.

Hope this helps.

Jon