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Recommendations for main venting

Hey Everyone, long time lurker - first time post.

I need help with proper sizing and recommendations for my main vent. 

The boiler is about 15 years old. This is my second year owning the house with this system. So far I have gone thru it and tightened / repaired that packing nuts that needed it and replaced all radiators with ventrite #1s. My last few radiators on the line take forever to heat up but eventually if the system runs long enough they will. I believe my problem lies in the main venting. 

1 pipe system with approx 80 feet of 2 inch pipe for the mains. Attached are a few pictures for reference. 

What should I do for the main venting? And proper size? 



  • Jamie HallJamie Hall Member Posts: 13,412
    Is that the main vent in your picture? That's cute. And hopelessly inadequate. For that main, I'd like to see at least one Gorton #2. Maybe two, on a nice antler.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • gfrbrooklinegfrbrookline Member Posts: 631
    Agree with @Jamie Hall or you could do 1 Barnes and Jones Big Mouth. I have a combination of both on my system.
  • nicholas bonham-carternicholas bonham-carter Member Posts: 8,193
    Your pressuretrol appears to be set too high, and high pressure will interfere with, or destroy any vents in the system.
    Get a good low pressure gauge on the same pigtail, so you know what your pressure is in ounces.—NBC
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 7,315
    And clean the pigtail under the pressure control.
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