Automatic air vent

[lenny]

Hi,


Should the cap on and AAV be left loose, tightened or completely taken off when a system has been fully purged?

Thanks

Len😕

 

[kirkgas]

it must be left loose to allow air to escape,

 

[Billy Bob Bob]

left loose also somewhere for the steam to go if the pump fails(not all boilers have pump pressure switches)

 

[josh]

left loose also somewhere for the steam to go if the pump fails(not all boilers have pump pressure switches)

What a load of rubbish, thats partly what pressure reliefs are for.
We don't use automatic air vents anymore as they always leak after a few years.
Once the system has been filled and vented you shouldn't need to leave it open.