On Jan. 3, 2017, ASA submitted public comments to generate the 2018 edition of the Uniform Plumbing Code (UPC) and the 2018 Uniform Mechanical Code (UMC). The public comments submitted were discussed and reviewed by the ASA Codes and Standards (C&S) committee during a teleconference meeting on
Nov. 7, 2016. The C&S committee is composed of experts in the HVAC, hydronics, plumbing and PVF industry. Members of the committee range from manufacturers to distributors located throughout the United States. One of the major issues discussed by the C&S committee relates to the sizing of the trap and trap arm for single- and multi-head standing showers. The current 2015 UPC (Table 702.1) requires a minimum 2 in. for the trap and trap-arm for single- or multi-head showers.
During the 2015 proposal meeting held in Denver, the UPC Technical Committee discussed and reviewed proposals submitted to the 2015 edition of the UPC. One of the proposals submitted revises the current requirement of 2 in. to 1 1/2 in. for the trap and trap-arm size for standing showers. The proposal achieved the necessary majority affirmative votes during the Technical Committee meeting but failed to achieve the necessary 2/3 affirmative during official balloting. There were arguments made by both sides.
Committee members who voted to approve the change to 1 1/2 in. argue that opponents have never submitted valid statistical evidence that the smaller trap sizes have a higher rate of clogging or require more intensive efforts to remove the alleged clogs. The AWWA Residential End Use Study provides evidence that the vast majority of U.S. bathing uses a combination bath/shower fixture where the UPC requires only 1 1/2 in. minimum. If a problem really existed, there would be overwhelming evidence from more than 85% of homes in the U.S.
Committee members who voted against the motion to change the size to 1 1/2 in. argue that in a bathtub, neither a strainer nor a drain body comes into play, and that they will have different flow characteristics through the drain body than through a standpipe connected to the inlet of a p-trap. Others argue that many clogs and failures occurred despite the fact that the flow rate through the smaller trap is greater. The velocity through the trap is like “a ‘red herring’ – when servicing a shower or replacing a shower, the larger trap size is much easier to clear and more importantly is not likely to clog.”
ASA’s C&S committee discussed the above issues during its teleconference meeting and reached consensus to submit a public comment asking the UPC Technical Committee to allow a 1 1/2-in. trap and trap-arm in the 2018 UPC. There were other plumbing topics discussed by the C&S committee, such as wall-hung fixtures, waste fittings, overflows and drainage connections to commercial dishwashing machines. The UMC topics discussed include flex ducts, factory-made air ducts and connectors, expansion tanks and materials for hydronic system piping, tubing and fittings. The C&S committee’s discussion materials, including all public comments submitted and meeting minutes, can be found on ASA’s website in the Codes and Standards section.
Public comments submitted to the UPC and UMC will be discussed and addressed by the IAPMO UPC and UMC Technical Committees on May 1-5, 2017, in Anaheim, Calif. ASA plans to be in attendance and feels privileged to participate in the code development process. Furthermore, the submission of the public comments by the C&S committee is an indication of the commitment and passion that exist amongst ASA members. As a whole,
the industry should do its part to better the model codes by participating in
Learn more: www.asa.net/Codes-Standards
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