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Venting Mains - Steam Newbie Math Check

Hello everyone.

Having recently purchased a house with 1-pipe steam (after having rented another hosue with steam for 2 years previously), I'm settling into my first cold snap and am working to undo all of the Knucklehead adjustments that have been made by the previous owners.

I have adjusted the system pressure down from 8 (yikes) to .5 with great success. Everything's much quieter now and the basement is much cooler already.

However, this split level house has a LONG main-run loop, and I'm pretty sure it's not vented properly. I was hoping someone with more experience could take a look and confirm/deny my thinking before I invest in several Gorton 2s.

Off of the boiler, there is a 2" main that runs for 33.5 feet, at which point a 1.5" return pipe connects and runs 32 feet back to the boiler. See photo below. At the BOILER end of this smaller return is a Gorton 1.

Going back to where this smaller return split off, the 2" main CONTINUES another 75.5 feet before ending up back at the boiler, where there is another Gorton #1.

By my calculations, using the Gill/Pajek chart, it takes nearly 4.5 minutes to vent JUST the mains in this scenario, there being 2.955 cu. ft. of air in the mains, and Gorton 1s venting at .330 CFM.

I'm thinking to replace the Gorton 1s with Gorton 2s, and perhaps adding a SECOND Gorton 2 at the end of the line... for a total of 3, venting at 3.3 CFM and reducing my Main venting time to around a minute.

Being new at this, I'm open to a second, third, and fifth opinion...

Thanks so much!


  • BobC
    BobC Member Posts: 5,480
    Try timing the time it takes for the steam to travel from the start of the main to it's end. All of that pipe has to be brought up to steam temperature so it should be insulated. You might need 3 Gorton #2's at the end of the main, you can start with 2 of them just be ready to add another if you need it. In each case get the vents up as high as you can.

    Take another photo of the boiler and it's connections to the steam main, that near boiler piping looks suspicious. You should insulate all of that piping with 1" fiberglass pipe insulation to speed things up.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Steamhead
    Steamhead Member Posts: 16,998
    My guess is that at the point where the first return line takes off from the main, the main also jumps up to a higher elevation. If so, the first return line is only there to drain the condensate from the first part of the main- not for venting air. This arrangement is called a "rise and drip".

    You want all your venting at the end of the main- this way the entire main has access to all your vents.

    I'd plug the vent opening on the first return line, and install three Gorton #2 vents on the second one.

    And, what Bob said about insulation.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Abracadabra
    Abracadabra Member Posts: 1,948
    I hate doing math... :D If I'm building a main vent station, I'll add a ball valve at the end of the antler, run the boiler a cycle. Time how long it takes steam to get to main vents with ball valve open. Add main vents till time with the vents and ball valve closed is the same as with the ball valve open.
  • cnjamros
    cnjamros Member Posts: 76
    Thanks, Bob and Steamhead.

    Bob, I'm attaching new images of that near-boiler setup for you to see. I'm not thrilled about the copper, but oh well.

    It looks like the returns have two legs that drop into the loop… one from that condensate return and one from the end of the main.

    The sill cock and ball valve you see are from the return of a hot-water loop.

    I'm working towards putting 3 Gorton 2s at the end of the main on both of your advice. I do think I'm going to leave at least a single "1" on the end of that condensate return, just for good measure… I mean, truth is STEAM never needs to get there, so it may not even make a difference. Is there any chance, if remove that vent, it becomes an air trap?

    The funny thing is, no one around here seems to carry the Gorton 2s… i had to order them online. They say no one ever asks for them. Everyone's trying to convince me to just add one more "1" and it should be fine.

    I want to tell them that when I have the pressure up high enough to get heat everywhere evenly with that setup, it takes a long time to bring the house to temperature and the basement is 90 degrees. Long live the Knuckleheads.

    In any case, I've ordered my parts and will let y'all know what happens when I get it installed.

    In the meantime, Bob, I'm interested in hearing what you have to say about this loop near the boiler, and also any other thoughts or experience people may have with a situation similar to mine.

  • Abracadabra
    Abracadabra Member Posts: 1,948
    cnjamros, no images were attached.
    cnjamros said:

    The funny thing is, no one around here seems to carry the Gorton 2s… i had to order them online. They say no one ever asks for them. Everyone's trying to convince me to just add one more "1" and it should be fine.

    It takes 3 #1s to almost equal a single #2. ;)

  • cnjamros
    cnjamros Member Posts: 76
    Ok, so I have successfully installed 6 Gorton 2s at the end of my 109' main.

    In my first test, it took approximately 8 minutes for the steam to get around the main. Not thrilled.

    I have done some further investigation and will post under a different topic to seek out advice. Thanks so much everyone.