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Replacing Main Vents, Piping Q

Looking for some advice on the best way to replace these severely undersized main vents. The system is parallel flow, single pipe steam. (Many of you should avoid looking at the near-boiler piping unless you want your blood pressure to rise. The boiler is older and approaching replacement soon.) The riser splits two ways and head about 20 ft to the front and back of the building, then the dry returns bring the condensate back. The existing main vents come out the top of those dry returns. The PVC piping above them now is being moved to give more headway (and access into the floor joists also). Main question is whether the new vents need to be piped higher. Any other advice is appreciated.


  • ethicalpaul
    ethicalpaul Member Posts: 5,702
    "Need" is difficult to say. If it were me, I'd pick up a couple MoM #1, or Gorton #1 if you hate MoM, and I'd see how they did.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    JUGHNE Member Posts: 11,062
    You could remove old vents, use short nipple and 90 (or street 90), horizontal run to clear PVC, riser up between floor joists, and install new vents. Gorton #2 would be adequate for each 20' main.
    Just be sure the horizontal part will drain back into the dry return, use swing 90's if need be.