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.

Main Vent Placement - What's Not to Like?

This main vent is teed and elbowed on the vertical at the end of the return. Not typical or recommended, maybe, but is it significantly less effective or likely to be a problem? If so, how? The installation is new smallest peerless. All piping is black but for the return vertical. System seems to be working well and quietly. Stock peerless gauge is 0-30, so don't have meaningful pressures. image


  • How high is the connection to the vent from the waterline. If it is less than than 30 inches, and you have more than one pound of pressure, the water in that return will submerge that tee, on the way to the vent.
    One hoffman 75 is good for about 8 feet of 2 inch pipe, so more Gorton 2's should be added, especially if they are using setbacks.--NBC
  • Steamhead
    Steamhead Member Posts: 16,230
    If it's high enough above the waterline, it'll work fine if the vent is the right size. How long is the steam main, and what diameter?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • kjbull
    kjbull Member Posts: 2
    Thanks for your responses. We've got about 28' of 2" diameter main. The tee for the vent is about 40" above the water line. The vent is a Gorton 1.
  • Somehow all that copper line made me think of the hoffman 75!
    It would be wise to use a vaporstat to make sure the pressure stays under 1 psi to keep that tee from becoming waterlogged by the rising return waterline
    Naturally, more main venting will be needed to prevent short-cycling.--NBC
  • BobC
    BobC Member Posts: 5,407
    28 ft of 2" main needs a lot more venting. It seems for optimum venting you would like a Gorton #2 for every 20 ft of 2" main. be warned that the Gorton #2 is much larger than the #1. You could use 3ea #1 to equal a #2.

    If you had a 0-3 PSI gauge you could measure the venting back pressure. I have a 12 ft 2" main that circles the chimney and I have 2 Gorton #1's and a Ventrite 35. My back pressure is a couple of ounces.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Captain Who
    Captain Who Member Posts: 452
    I'm thinking it might not be a bad idea to put some insulation on that very long 3/4" copper riser to the vent. That's a lot of high conductivity copper and when you are recovering from a setback you might want that steam to close the vent asap so that it is not taking steam pressure from the radiator takeoffs on the main. I know we want low pressure but we also want to get the steam flow into the rads evenly and promptly from a setback. I saw a Gerry Gill video where he said the Gorton #2 closes at around 110 F though, which is a lot earlier than lots of other vents. For example, varivalves don't begin to close until 155 F, typically.
  • BobC
    BobC Member Posts: 5,407
    i would try insulating half of the pipe between the vent and the main and see what happens. If that vents shuts down too fast it might starve the last radiators on the main because thae main might not fill fully with steam. i think it's kind of a seat of the pants thing.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge