Steam Main - Air Vent Locations

davidheating

Hello,

Looking for some help with my steam mains and particularly with venting. I currently only have one air vent on our steam mains in the basement and that vent is located on a 90 after the branch piping to the radiators. Is this air vent doing anything since it's after the branch piping? How would an air vent be added closer to the radiator on this side of the main?
On the other side of the main there is no air vent. There is a coupling with a plug, I'm assuming an air vent can be installed here. Any reason an air vent should not or could not be installed here?
After installing vents I plan to insulate all of the piping. Should I insulate the takeoff coming out of the boiler along with all of the fittings / unions?
Also, any concerns about the piping coming out of the boiler?

Below are photos related to my questions above.

dabrakeman

Main vents should be placed on the main anywhere after the last take off from that main.

ethicalpaul

Or just before it!

davidheating

dabrakeman said:

Main vents should be placed on the main anywhere after the last take off from that main.

So the air vent I have shown in the photo is in the correct location, and I should install a 2nd air vent on the other main after the take offs to those radiators?

ethicalpaul

Every main should have a main vent for best chance at good balancing.

In a pinch you could put a main vent in some creative places but right after or before the last radiator runout is best