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Please, check my work, vent question

ChrisJ Member Posts: 14,959
I just want to run my vent setup past everyone to see if its ok.  I have not had my final inspection yet and would like to know if this is safe ahead of time.

This is the only picture I have on hand,  I can take a better one when I get home if need be. 

I have two 90 deg elbows swiveled with a 6" pipe in between.  The B-vent is 6 inch as are all connections per the Boiler manufactures recommendation and local code.   One elbow is on the vent damper and the other goes directly into my B-vent.  All pipes are secured with screws except the elbow into the B-vent.  I did not see any easy way of doing this.

My one concern is the elbow into the B-vent isn't super snug like my other connections.  Sure, it fits inside of it and cannot come out but I wish it could be better.  The pipe is as short, vertical and direct into the B-vent as I could make it.

Should I use boiler cement on the connection into the B-vent or just leave it the way it is?
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment


  • Henry
    Henry Member Posts: 996
    B vent adapter

    By code, you are supposed to use a B-vent adapter to connect single wall vents.
  • ChrisJ
    ChrisJ Member Posts: 14,959

    Hi Henry,

    I could not find any such adapter.  All I found was this in an FAQ

    Screws are not needed to secure a connection because the connection is already UL listed as it is designed. However, there are exceptions that we allow screws and that is for connections of single-wall pipe to the B-vent. Fold back the outer wall locking tabs that can act like an access "door" to secure the aluminum inner wall and single wall pipe together using 1/4" stainless screws.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • VictoriaEnergy
    VictoriaEnergy Member Posts: 126
    Questionable instructions

    The last thing that should come in contact with the aluminum inner jacket of B vent is stainless steel.  It will induce the aluminimum to corrode rapidly, standard zinc plated screws will corrode but still last longer.

    Keep in mind aluminum also expands a lot with temp change that's why B vent lengths are always designed so the inner jacket is fastened to the outer shell at the top of each length only.

    Also keep in mind it's an atmospheric vent system that normally operates at a negative pressure so small leaks at the connection will result in room air getting drawn into the vent.

    Nice piping job.
    Home Owners Please Note:

    You are receiving advice from some very skilled pros completely free of charge. One of the reasons I participate is to sharpen my own troubleshooting skills. So; did we get it right? I would be grateful if you extend this courtesy back by posting the final outcome of the issue you are inquiring about. Thanks
  • Henry
    Henry Member Posts: 996

    Single wall to B-Vent adaptors are available. They are mandatory under B149 in Canada. Under NFPA54, 12.7.1 paragraph 1 specifies that the vent must be installed according to the manufacturers instruction. All B-Vent manufactureres specifie adaptors! Paragraph 4 even states that "Screws, rivets, and other fasteners shall not penetrate the INNER wall of double wall gas vents....except a single wall metal connector to a double wall vent" IE  a B-vent adaptor.
  • gennady
    gennady Member Posts: 839
    edited November 2011

    I think you cannot have copper on steam system.
  • Bob Harper
    Bob Harper Member Posts: 986
    b-vent adapter

    All B-vent mfrs. make a draft hood adapter, which is more correctly called a single walled pipe adapter. If you run long screws in through the bottom skirt of a section of B-vent through single walled pipe then into the male aluminum tail of the B-vent, the screw will tend to push the alum. inner section inwards like a daisy petal thus severely restricting the flue while not providing adequate mechanical connection. The Bvent adapter will typically not suffer this problem because you are penetrating two layers of metal and hopefully with sharp point 1/2" screws such as Zip Screws. Do NOT use TEK drill point screws!
  • lchmb
    lchmb Member Posts: 2,997

    below the water line, copper is acceptable...
This discussion has been closed.