1/2" Male NPT AirVent Automatic High Capacity Air Vent

I used on the hydronic heating system roof air valves works beautifully

This is a high-capacity air vent that comes with a service check valve. The check valve only goes into operation when you remove the air vent for servicing. So you don't need to shut down and drain the system in case you need to service or replace the air vent. Also, this comes with a hygroscopic cap that automatically stops water leaking from the vent in case the float inside is stuck. Great design. I recommend it without hesitation. I used this to replace the air vent that came with a System 2000 EK-1 boiler.

I had one of these on my boiler previously and always had troubles with air purging itself from the system. I got this to go on my boiler about 2 days before I had to replace the boiler, and had the whole system redesigned. Since this was brand new, we used it on the new system and it never would purge the air out. We finally yanked it out and installed a different maker of auto vent and it worked perfectly Bled most of the air out in a few minutes, and the last few stragglers within a couple of hours as they circulated thru the system. Can't say I would ever by this style again.

Seems to be working as designed. I installed this into the top of my boiler as it seems air likes to accumlate over time in my boiler. I think it is all the small microbubbles from the heating of the water accumlating at the top of the boiler. When the accumlation of all the bubbles form a large bubble, it breaks free and gets dispersed into the rest of the system. This air vent allowed air to escape while filling the system then shut as soon as the water reached the top. The discs then swelled to stop any water leakage. I have yet to have to use the boiler this season for home heating but am very optomistic of the air vent doing what I need it to do.