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  • Max. Vent

    A little object for discussion.

    Our maximum length we can run a 2" horizontal vent is 1/3 the total vertical length of 120'(40')

    1-1/2"s maximum length is 1/3 of the total vertical length of 60'(20')

    Here is what we have.

    From the vent stack there is 30 feet of 2" horizontal vent piping to a W/C.There is one branch that comes off of that 2" vent and runs another 30' horizontal to a hand sink this fixture only needs 1-1/2".

    The 1-1/2" vent needs to be increased 1 pipe size to increase the allowable distance to an undetermined length(not in the chart,most say infinity).

    So now the hand sink vent is 2" at 30'

    The W/C is 2" at 30' which is under the maximum.

    Could a person say that the 2" vent line is now sixty feet and needs to be increased one pipe size.

    I say "no" the larger 2" from the hand sink is only to increase that branch and does not affect the atmospheric pressure on the W/C vent.

    Hope I did not make it too confusing.If I did you guys know it won't be the first time

  • #2
    Re: Max. Vent

    Originally posted by drtyhands View Post
    A little object for discussion.

    Our maximum length we can run a 2" horizontal vent is 1/3 the total vertical length of 120'(40')

    1-1/2"s maximum length is 1/3 of the total vertical length of 60'(20')

    Here is what we have.

    From the vent stack there is 30 feet of 2" horizontal vent piping to a W/C.There is one branch that comes off of that 2" vent and runs another 30' horizontal to a hand sink this fixture only needs 1-1/2".

    The 1-1/2" vent needs to be increased 1 pipe size to increase the allowable distance to an undetermined length(not in the chart,most say infinity).

    So now the hand sink vent is 2" at 30'

    The W/C is 2" at 30' which is under the maximum.

    Could a person say that the 2" vent line is now sixty feet and needs to be increased one pipe size.

    I say "no" the larger 2" from the hand sink is only to increase that branch and does not affect the atmospheric pressure on the W/C vent.

    Hope I did not make it too confusing.If I did you guys know it won't be the first time


    hat's for sure

    Comment


    • #3
      Re: Max. Vent

      Max distance from stack on 2" is 60...max on 1-1/2" is 20.
      Unless I misunderstand, you're asking if it's ok to tie the 1-1/2" into the 2" thats 30' away from the stack as is.
      If thats what you mean, I'd increase the 1-1/2" to 2".
      Even if you could consider the 2" the vent stack...it's still 30' with 1-1/2".
      I read that right?

      Comment


      • #4
        Re: Max. Vent

        Originally posted by drtyhands View Post
        A little object for discussion.

        Our maximum length we can run a 2" horizontal vent is 1/3 the total vertical length of 120'(40')

        1-1/2"s maximum length is 1/3 of the total vertical length of 60'(20')

        Here is what we have.

        From the vent stack there is 30 feet of 2" horizontal vent piping to a W/C.There is one branch that comes off of that 2" vent and runs another 30' horizontal to a hand sink this fixture only needs 1-1/2".

        The 1-1/2" vent needs to be increased 1 pipe size to increase the allowable distance to an undetermined length(not in the chart,most say infinity).

        So now the hand sink vent is 2" at 30'

        The W/C is 2" at 30' which is under the maximum.

        Could a person say that the 2" vent line is now sixty feet and needs to be increased one pipe size.

        I say "no" the larger 2" from the hand sink is only to increase that branch and does not affect the atmospheric pressure on the W/C vent.
        I say "no" also. If you added another WC where the hand sink is and ran a 2" to the other 2" you wouldn't call it a 60' run.

        Hope I did not make it too confusing.If I did you guys know it won't be the first time
        Tracy
        sigpic.................I Love My Toto Bidet :twofinger2: :twofinger:

        Comment


        • #5
          Re: Max. Vent

          Duck,the hand sink is an additional 30'.It is also one pipe size larger(2") because it is over it's allowable length.

          Now that the entire 2" vent is 60' one could argue I'm over.
          Even though I'm only oversizing the 30' of 1-1/2" to give me more distance on that fixture.

          Comment


          • #6
            Re: Max. Vent

            I always took that code to refer to the individual fixture's vent rather than the entire venting system. In this case, upsizing the hand sink to 2" would satisfy the requirement. The WC vent already satisfies it.
            Brent

            Comment


            • #7
              Re: Max. Vent

              Adam, sounds like your code bases the total horizontal vent distance on the vertical drop.
              We base our vent distances on total f.u.'s (my excuse for not clearly understanding...yup, sure).
              Whats got me confused is the fact that the 2" only goes 40' (1/3 of 120) while the 1-12" can go 20' (1/3 of 60).
              With both fixtures on the same floor, I'm only guessing the 120' and 60' differences mean they each drop & connect to the stack at different intervals below (12th floor?).
              Looks like the dilemma is where you said there's no mention in your code for max distance on the increased vent size.
              Bottom line, I might only be confusing you more if I try to go by my code, but I'm with Tracy / Yasuda.
              On a side note, would it just be easier to make it a circuit vent?

              Comment


              • #8
                Re: Max. Vent

                Is this copper,C I ,ABS. If it's ABS ,and not a housing track size project,why not use 2"? The $ is lite. Might have a problem with The inspector ,right?
                I can build anything You want , if you draw a picture of it , on the back of a big enough check .

                Comment


                • #9
                  Re: Max. Vent

                  My mistake,I now realize this is not all new ,and a remodel. Sorry
                  I can build anything You want , if you draw a picture of it , on the back of a big enough check .

                  Comment


                  • #10
                    Re: Max. Vent

                    It's all good Tool

                    Actually it's 2" copper in a tenant improvement(remodel).

                    There was something you were gonna say?

                    Comment


                    • #11
                      Re: Max. Vent

                      Duck,
                      The waste and vent system is done.I am just informing myself(thanks to you guys) so I can be prepared for a pissed off inspector.

                      I already explained everything about the sour inspector in the construction forum.

                      Thank you though

                      How does a circuit vent differ from a combination waste and vent system? I googled circuit vent and the diagrams look similar to comb.W&V systems I have done in grocery stores.

                      Comment


                      • #12
                        Re: Max. Vent

                        Bought 4 sticks of 2" DWV copper last month $187 each ,ouch . At 1st I assumed it was all new ABS.
                        I can build anything You want , if you draw a picture of it , on the back of a big enough check .

                        Comment


                        • #13
                          Re: Max. Vent

                          I may be wrong but from what I have read, and I will quote it so I don't mess it up. But a Vertical Combination waste and vent "some codes require special approval...
                          Low Unit Rated Fixtures (like lavatories, bidets, bathtubs, showers and sinks) can use a Combination waste and vent stack. If this arrangement is used, remember the following restrictions"

                          The stack must be vertical and must extend full size through the roof. A 3-inch combination waste and vent stack can't be reduced above the top most fixture.

                          The stack can not be connected to another existing vent pipe below the roof.

                          Check the maximum number of fixture units and pipe sizes carefully. Plumbing codes vary considerably in this area.

                          You can not place a kitchen sink on a 2 inch for example you can't connect a kitchen sink to a 2 inch stack on the first floor that is extended to a 2nd floor bathroom and recieve waste from say a lav.

                          or a Lav on the first floor and a lav on the second floor located directly over one another could both be served by a combination w & v pipe."

                          and a Circuit vent

                          "serves two or more fixtures and rises vertically from between the last two fixture traps on a horizontal branch drain. This vent must then connect to the vent stack."

                          I hope this helps... Or I maybe confused. This info came from BASIC PLUMBING WITH ILLUSTRATIONS BY HOWARD C. MASSEY. It is a book I am reading through right now has a bunch of good info.

                          Billytwohatz

                          Comment


                          • #14
                            Re: Max. Vent

                            Originally posted by toolaholic View Post
                            Bought 4 sticks of 2" DWV copper last month $187 each ,ouch . At 1st I assumed it was all new ABS.
                            That copper sure makes for a pretty job though,doesn't it Tool

                            Comment


                            • #15
                              Re: Max. Vent

                              I think I read a book by Massey,something giving advice to plumbing contractors.It was back in the early 90's.

                              Comment

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