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  • #16
    Re: Replacing verticle vent pipe that runs above roofline, can I substitute 4" with

    Originally posted by rich121 View Post
    Well, since you want to talk electrical, there is always going the next size down for the neutral in a service, or the smaller sizes of conductor for the ground..etc.... in certain circuits, such as welders, you can use 30A wire for a 60A welder due to duty cycle...many other exceptions, rules, code etc. for other circuits...

    I'm asking because I want real world, not some smart *** comment ...as with any trade, there are exceptions, calculations, standards etc.
    I don't think Tool was being smart. He is one of the nicest guys on this forum. I believe sometimes when we read these posts they all have different meanings to us. I had the same thing happen to me, I was like give me a break but the member who did it is cool, very knowledgable and always try to help you.. Hope this helps. Thanks for the info. I am new on here myself .
    Last edited by Fred the plumber; 05-15-2011, 07:04 AM.
    The Plumber/Firefighter

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    • #17
      Re: Replacing verticle vent pipe that runs above roofline, can I substitute 4" with

      OK, the reality is that venting size is just one aspect of functional drainage.
      If everything else is done right...pitch, fittings, etc....and the system point
      where the piping draws air is already 4", then nothing is wrong with reducing
      the riser to 3". Few, if any, residential codes require 4" venting anymore unless
      it's a freakin' palace. Many have even done away with the 3" requirement.
      Like it was said, it all depends on the DFU's and most codes have increased
      that number allowed now. I'm all for doing things the right way. In fact, I
      like to follow the "code plus" principle, when possible. Hard to do in new work
      where the profit margin is very tight due to competitive bidding. But, in your
      case, be practical. Just because it was required by code 50 years ago
      doesn't mean you have to do it now.

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      • #18
        Re: Replacing verticle vent pipe that runs above roofline, can I substitute 4" with

        OK, I'LL BE NICE. Here in S.F. You must use the same size vent as the main drain! 4" drain 4 " vent. Under My license I pull elec. permits, and wire projects,including new services. Have a nice Day. And thanks Fred ! P.S. How many fixture units is that old vent handeling? Sounds like one of those mansions on Capitol hill. Huge homes like S.F. in many ways.
        Last edited by toolaholic; 05-15-2011, 12:38 PM. Reason: Had My Coffee !
        I can build anything You want , if you draw a picture of it , on the back of a big enough check .

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        • #19
          Re: Replacing verticle vent pipe that runs above roofline, can I substitute 4" with

          Different codes for different areas. In Fla. you must have at least one
          stack the size of which is not less than one-half of the required size of
          the building drain. That's why you don't see any vents over two inches
          on residential any longer.

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          • #20
            Re: Replacing verticle vent pipe that runs above roofline, can I substitute 4" with

            and in chicago min 4" through roof and if the stack is 4" u must up size 1" so they sell 4x5 increasers dont matter if all your venting is a lav sink the vent would go up 1 1/2" and increase through roof 1 1/2"x4"
            Last edited by post plumber; 05-16-2011, 09:11 PM.
            SMELLS LIKE $$$$$$ TO ME

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