Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Automatic air vent location

Rickoo Member Posts: 54
I'm installing an HTP Superstor indirect water heater on a Peerless oil fired boiler and had planned on installing an automatic air vent in the boiler loop. I assumed the best location would be on the supply side but had read folks sometimes install then on the return. Which is the correct location?

Would these Honeywell vents be a good option?



  • yellowdog
    yellowdog Member Posts: 159
    in general you shouldn't need one at all if you have air elimination on your boiler header. installing one will only lead to future leaks and unnecessary maintenance.
  • Rickoo
    Rickoo Member Posts: 54
    Thanks Yellowdog. The boiler has air vents both on the top of the boiler and at the air scoop in the supply header. I guess I figured for the cost of a vent, it couldn't hurt to have there?
  • mattmia2
    mattmia2 Member Posts: 9,949
    edited March 2023
    As long as you have the valving to purge it well enough to get it flowing the air elimination at the boiler should get rid of the rest of it. If I were going to put effort in to air elimination I would replace the air scoop with a modern microbubble air separator and make sure it is at the highest temp and lowest pressure point.
  • hot_rod
    hot_rod Member Posts: 22,472
    Air vents vs air purgers.
    Float type auto vents are for high point air elimination. They do little if anything just screwed into a horizontal pipe. Manuyal air vents are another high point option.

    Cast iron Camel hump air purgers add some, very little value. They can grab big air when properly installed, but not the more problematic micro, entrained and dissolved air.

    Use them together, air purger at the boiler outlet, auto vents at high points.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream