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Main Vent at an Angle? Tap Size?

I have a couple questions about our main vent. I hope it is okay to combine them here in a single discussion - consider the primary question to be "how do I need to improve our main vent setup"?

This is all prompted because I removed the main vent last weekend to clean it (it had been spitting water). This is our sixth winter in this house (2 finished floors, mid-block rowhouse, about 1450 finished sq ft).

When reinstalling I was unable to get the vent to remain completely vertical. The best I could do is by wiring it up, as shown. I can't get another full revolution out of that first elbow, even though it was completely vertical before I started messing with it. It did seem precarious then, too.

Here are my real questions:

1. Does the vent have to be completely vertical, or is the current angle (70°ish?) sufficient?

2. Does a 1/4" tap on the main pipe give enough room for the vent to work at its capacity? I notice the vent itself is 1/2", so that makes me think it is intended to have a 1/2" or larger nipple feeding it.

3. Should I just re-tap the pipe at 1/2" and replace the first elbow and the close nipple that connects it?

Any thoughts and opinions are appreciated. Let me know if there is another photo or better description.




  • Jamie Hall
    Jamie Hall Member Posts: 22,916
    Well... that's a pretty small vent to act as a main vent -- so you're fine as far as fitting size is concerned. It should be vertical -- it may spit at that angle, as the float which is supposed to keep it from spitting may not seal at that angle. I'm not quite sure how I'd rearrange that...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattmia2
    mattmia2 Member Posts: 9,413
    replace the 45 with a 90 and a street 90 to make a swing joint that you can point up and turn the fitting in the main counterclockwise until the nipple has a very shallow angle and you can get clearance for one or more large vents
    JUGHNE Member Posts: 11,021
    I do believe that a 1/4" tap will be adequate for a Gorton 2 main vent.
    That is the largest main vent other than the B&J Big Mouth.

    That usually would be considered too small for a main vent.
  • Big Ed_4
    Big Ed_4 Member Posts: 2,696
    Extend the nipple from the street El to the 45 and shorting the rise to a close nipple may straighten it out. You may have to punch a hole in the ceiling to fit a bigger vent . The main vent was added later in its life . I guess they only had the drill and tap for 1/4" .. Better than none ....
    I have enough experience to know , that I dont know it all
  • Steamhead
    Steamhead Member Posts: 16,723
    Look at that reducing tee before the vent- water is backing up there, probably banging and that's why the vent was spitting.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    EBEBRATT-Ed Member Posts: 15,317
    That return pipe is too small to tap anything larger that 1/4" in my opinion
  • bjones
    bjones Member Posts: 1
    Thank you all for your comments and suggestions. I'll look at various combinations of angle fittings to get it more vertical.

    I did a little more research and some math based on the questions about whether or not the Hoffman 4A is too small. The math, based on .023 cu ft per foot of 2" pipe works, out to .805 cu ft of air to be vented. I saw somewhere on here that the 4A only vents .4 (half what's needed), but the Hoffman 75 is over 1.

    So I wonder if I should either add a second 4A, or swap it entirely for a 75 (or, I see lots of suggestions for the Gorton #1).
  • SteamCrazy
    SteamCrazy Member Posts: 100
    Hello, can you send another picture of where that condensate pipe is going? The after the vent.
  • SteamCrazy
    SteamCrazy Member Posts: 100
    It may help with solution.
  • bjones
    bjones Member Posts: 1
    Here's a wider photo showing the condensate pipe. It runs straight along the wall 35' back to the boiler.

    That duct and gas line are for a clothes drier; unrelated to the heating system.