Announcement Announcement Module
Collapse
No announcement yet.
What point do you go from 3/4" to 1/2" supply Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • Filter
  • Time
  • Show
Clear All
new posts

  • What point do you go from 3/4" to 1/2" supply

    I guess codes may vary, but what is the general rule for where it permissible to adapt down from the 3/4" water supply to 1/2" pipe?

  • #2
    Re: What point do you go from 3/4" to 1/2" supply

    In the wall before each fixture , is how I do it.
    I can build anything You want , if you draw a picture of it , on the back of a big enough check .

    Comment


    • #3
      Re: What point do you go from 3/4" to 1/2" supply

      Your code book should be your guide. Being in California, I refer to 2010 CPC Tables 6-5 and 6-6. Come Thursday Jan. 2, it will be the same tables but in CPC 2013. Or, if specifications call for something more restrictive, then that is the way you must go.

      Comment


      • #4
        Re: What point do you go from 3/4" to 1/2" supply

        Really, Tool? 3/4 to every fixture? Hot & cold?
        I am not aware of a "general rule" for pipe sizing.
        There are too many variables. Codes being the main thing.
        Also the combined minimum flow rates for the fixtures being supplied.
        Also the type of piping system makes a difference.
        Is it looped to each fixture or is it parallel manifold distribution?
        Residential? Commercial?
        Need more info.

        Comment


        • #5
          Re: What point do you go from 3/4" to 1/2" supply

          i do it as tool does. get the max volume to each location and reduce down where convenient. you never know what changes will take place in the future and having that line already there makes life that much easier.

          when i build my new house im taking 1" to all the areas... but most customers wont pay for this.
          ~~

          ... it was plumbed by Ray Charles and his helper Stevie Wonder

          Comment


          • #6
            Re: What point do you go from 3/4" to 1/2" supply

            And.... the codes may be changing how they size different fixture loads which makes sense since the Hunter Curve (which both DFU and WSFU's are based on) has been increasingly inaccurate as more and more water saving fixtures have been mandated.

            IAPMO, ASPE, WQRF to Collaborate on Hunter's Curve Research Project The International Association of Plumbing and Mechanical Officials (IAPMO®), American Society of Plumbing Engineers (ASPE) and the Water Quality Research Foundation (WQRF) will jointly fund a research project using data provided by Aquacraft Inc. to update Hunter's Curve for estimating water supply for residential applications using water efficient fixtures.
            The research project will provide statistical analysis of fixture use behavior in single-family residential homes, extended to include multi-family dwellings, using the latest data sets for 2010-11 as provided by Aquacraft Inc., a water management, research and use analysis firm.
            Data sets representing a sampling of 1,300 homes will allow the mining of thousands of individual fixture samples to determine the probability of the fixtures' end usage. Probabilities derived from this research will be used as a foundation to develop a statistical probability model for an estimating design curve for residential application.
            In July 2011, IAPMO and ASPE convened a special task force to revise the methodology for properly sizing plumbing systems in response to the increased use of high-efficiency plumbing fixtures, fixture fittings and appliances and the subsequent decreased demand for water in commercial buildings and residences. To assist with the mathematical and statistical aspect of the work, ASPE appointed three high-profile members — Jason Hewitt, PE, CPD, LEED AP, of CB Engineering; Tim Wolfe, PE, of KJWW; and Thomas Poerio, Ph.D., PE, LEED AP, of Univesco, LLC — to work with Dan Cole, IAPMO's technical services supervisor. In addition to the ASPE appointees, Steven Buchberger, PhD, PE, professor of Environmental Engineering at the University of Cincinnati, is assisting in statistical analysis.
            "Such a large-scale statistical analysis of hourly use and flow patterns of plumbing fixtures common in residential occupancies has never been done," Cole said. "The original Hunter model for public use was based on assumptions only, not data. The Hunter model for private use was based on morning calls in two hotels and one apartment. The scope of this project greatly surpasses the original work piloted by Dr. Hunter. We are excited about the potential results this project may bring forth for more accurate water supply demand estimates, efficient pipe sizing, and precise metering."
            "ASPE is committed to supporting this critical research that will provide our members with statistically sound information that will assist them in designing plumbing systems that are even more efficient and cost effective," stated Jim Kendzel, ASPE Executive Director/CEO. "The plumbing industry needs to continually invest in research to be able to provide the public with a safe and efficient water supply and ASPE is proud to be working with IAPMO and WQRF in supporting this project."
            The research project is expected to conclude by year's end and its findings applied to a code proposal for a future edition of the Uniform Plumbing Code (UPC®).

            Comment


            • #7
              Re: What point do you go from 3/4" to 1/2" supply

              I'm not actually running pipe. I inspect homes for a property management company. In one house the plumber, probably the owner of the house, adapted down to 1/2" coming out of the water heater. I knew this wasn't right and I just wondered how far the 3/4" pipe had to go before changing to 1/2". I see now that there's no simple answer to the question. Thanks

              Comment


              • #8
                Re: What point do you go from 3/4" to 1/2" supply

                Originally posted by Big Jim View Post
                Really, Tool? 3/4 to every fixture? Hot & cold?
                I am not aware of a "general rule" for pipe sizing.
                There are too many variables. Codes being the main thing.
                Also the combined minimum flow rates for the fixtures being supplied.
                Also the type of piping system makes a difference.
                Is it looped to each fixture or is it parallel manifold distribution?
                Residential? Commercial?
                Need more info.
                I'm a bad Man !
                I can build anything You want , if you draw a picture of it , on the back of a big enough check .

                Comment


                • #9
                  Re: What point do you go from 3/4" to 1/2" supply

                  Well if you are inspecting then what are the standards you inspect to if not the applicable codes.

                  Its not a difficult answer, just look it up in the code book.

                  Your answer would be that the pipe appears to be undersized for the number of fixtures units served.

                  If you were insepcting as a plumbing inspector you do not have to tell them what is wrong, why? They are supposed to know, and, if you tell them and they address that infraction and YOU, the inspector are wrong or incomplete in your identification of the problem then you might cause the agency to be responsible for costs associated with making it right on the second fix. When I took the plumbing inspectors class that is how it was explained to me by the long time inspector teaching the class. It had often wondered why they never would go into detail on plan reviews and such, only marking up the drawing gs and telling you the section you were not in compliance with and leaving it for you to figure out where all the infractions were, because if they ID'd them and missed one then you have a problem.

                  So short story, look it up and know what it should be.
                  ---------------
                  Light is faster than sound. That's why some people seem really bright until you hear them speak.
                  ---------------
                  “If I had my life to live over again, I'd be a plumber.” - Albert Einstein
                  ---------
                  "Its a table saw.... Do you know where your fingers are?"
                  ---------
                  sigpic http://www.helmetstohardhats.com/

                  Comment


                  • #10
                    Re: What point do you go from 3/4" to 1/2" supply

                    we have many houses here that have only a 5/8" OD water line coming in. Running 3/4" off these meters has no real benefits. My cousin's house is this way and even piped with 1/2" pex he has no flow, pressure or volume problems.
                    ~~

                    ... it was plumbed by Ray Charles and his helper Stevie Wonder

                    Comment


                    • #11
                      Re: What point do you go from 3/4" to 1/2" supply

                      OK. I'm not a plumbing or code enforcement inspector. I do turnover inspections on rental properties. I just make a list of what the place needs to be ready for the next tenant. Many places will need to meet Section 8 requirements but the Section 8 inspector has no clue about building codes. They just go off a check list they're given. If water comes out of the faucet with a decent flow, they're satisfied. I was just curious what the rules were about pipe sizing. I though there may be some basic rules on it, but now I've learned that's not the case. Thanks

                      Comment


                      • #12
                        Re: What point do you go from 3/4" to 1/2" supply

                        Originally posted by Plumbus View Post
                        And.... the codes may be changing how they size different fixture loads which makes sense since the Hunter Curve (which both DFU and WSFU's are based on) has been increasingly inaccurate as more and more water saving fixtures have been mandated.

                        IAPMO, ASPE, WQRF to Collaborate on Hunter's Curve Research Project The International Association of Plumbing and Mechanical Officials (IAPMO®), American Society of Plumbing Engineers (ASPE) and the Water Quality Research Foundation (WQRF) will jointly fund a research project using data provided by Aquacraft Inc. to update Hunter's Curve for estimating water supply for residential applications using water efficient fixtures.
                        The research project will provide statistical analysis of fixture use behavior in single-family residential homes, extended to include multi-family dwellings, using the latest data sets for 2010-11 as provided by Aquacraft Inc., a water management, research and use analysis firm.
                        Data sets representing a sampling of 1,300 homes will allow the mining of thousands of individual fixture samples to determine the probability of the fixtures' end usage. Probabilities derived from this research will be used as a foundation to develop a statistical probability model for an estimating design curve for residential application.
                        In July 2011, IAPMO and ASPE convened a special task force to revise the methodology for properly sizing plumbing systems in response to the increased use of high-efficiency plumbing fixtures, fixture fittings and appliances and the subsequent decreased demand for water in commercial buildings and residences. To assist with the mathematical and statistical aspect of the work, ASPE appointed three high-profile members — Jason Hewitt, PE, CPD, LEED AP, of CB Engineering; Tim Wolfe, PE, of KJWW; and Thomas Poerio, Ph.D., PE, LEED AP, of Univesco, LLC — to work with Dan Cole, IAPMO's technical services supervisor. In addition to the ASPE appointees, Steven Buchberger, PhD, PE, professor of Environmental Engineering at the University of Cincinnati, is assisting in statistical analysis.
                        "Such a large-scale statistical analysis of hourly use and flow patterns of plumbing fixtures common in residential occupancies has never been done," Cole said. "The original Hunter model for public use was based on assumptions only, not data. The Hunter model for private use was based on morning calls in two hotels and one apartment. The scope of this project greatly surpasses the original work piloted by Dr. Hunter. We are excited about the potential results this project may bring forth for more accurate water supply demand estimates, efficient pipe sizing, and precise metering."
                        "ASPE is committed to supporting this critical research that will provide our members with statistically sound information that will assist them in designing plumbing systems that are even more efficient and cost effective," stated Jim Kendzel, ASPE Executive Director/CEO. "The plumbing industry needs to continually invest in research to be able to provide the public with a safe and efficient water supply and ASPE is proud to be working with IAPMO and WQRF in supporting this project."
                        The research project is expected to conclude by year's end and its findings applied to a code proposal for a future edition of the Uniform Plumbing Code (UPC®).

                        A lot of words with very little useful information .
                        I can build anything You want , if you draw a picture of it , on the back of a big enough check .

                        Comment


                        • #13
                          Re: What point do you go from 3/4" to 1/2" supply

                          Let me translate for you, Kevin. They are going to reevaluate the calculations Hunter used to come up with his Curve using modern fixture intakes and discharges, as well as modern testing equipment. it should effect the numbers in the tables quite a bit. In other words, it will allow us to use smaller pipes, which is a very big deal. And, in my opinion, way overdue.

                          Comment


                          • #14
                            Re: What point do you go from 3/4" to 1/2" supply

                            Originally posted by Plumbus View Post
                            Let me translate for you, Kevin. They are going to reevaluate the calculations Hunter used to come up with his Curve using modern fixture intakes and discharges, as well as modern testing equipment. it should effect the numbers in the tables quite a bit. In other words, it will allow us to use smaller pipes, which is a very big deal. And, in my opinion, way overdue.
                            except if the bureaucrats do it the way they always do...mostly wrong...the pipe sizes will increase and new taxes will be developed for using large pipes
                            ~~

                            ... it was plumbed by Ray Charles and his helper Stevie Wonder

                            Comment


                            • #15
                              Re: What point do you go from 3/4" to 1/2" supply

                              Originally posted by Plumbus View Post
                              Let me translate for you, Kevin. They are going to reevaluate the calculations Hunter used to come up with his Curve using modern fixture intakes and discharges, as well as modern testing equipment. it should effect the numbers in the tables quite a bit. In other words, it will allow us to use smaller pipes, which is a very big deal. And, in my opinion, way overdue.
                              The text looks more Lawyer than Plumber !!
                              I can build anything You want , if you draw a picture of it , on the back of a big enough check .

                              Comment

                              Working...
                              X