Air/pressure release valve help

[cyberbob133]

Hi i have this valve plumbed into a double grundfos pumpplan - there is a red plastic screw on top - does anyone know whether this should be partly open or fully closed - Its fully closed now - i do have air in the system on occasion and have had to bleed the pumps - I have searched google and there are similar looking ones but i cannot pin it down for instructions.

thanks

 

[oldbuffer]

1. In theory they should be left open.
2. In practice, they often leak, so the cap is closed.
3. If I were you I'd open it to bleed the air out, then close it again.
4. If you really want it to be automatic:
4a. Shut water off.
4b. Remove old one.
4c. Fit an isolation valve.
4d. Fit a new automatic bleed valve.
4e. When it starts to leak, shut isolation valve and replace.

 

[ianmcd]

As @oldbuffer says they are supposed to be automatic air vents, but they are all cheap crap(every make) and leak for fun so most get closed to stop them leaking

 

[cyberbob133]

cheers thank you to both