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PVC for condensate in plenum spaces

Discussion in 'Mechanical Codes' started by jar546, Oct 11, 2019.

  1. jar546

    jar546 *****istrator

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    In other than one and two-family dwellings, does anyone allow PVC to be used as condensate disposal when the HVAC equipment is part of a plenum space and the return ducts are not directly connected to the air handler?
     
  2. mtlogcabin

    mtlogcabin Registered User

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    In a mechanical room then yes. Other areas most likely not. I think you need to be more specific in your description of the plenum space. Type of construction may allow it also but I don’t have a code book at home.
     
  3. steveray

    steveray Sawhorse

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    Nope....Better get a plenum rated condensate pump too...
     
  4. mtlogcabin

    mtlogcabin Registered User

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    There are exceptions for Plastic pipe in a plenum if they meet a certain listing.

    2018 IMC
    602.2.1.5 Discrete plumbing and mechanical products in plenums.
    Where discrete plumbing and mechanical products and appurtenances are located in a plenum and have exposed combustible material, they shall be listed and labeled for such use in accordance with UL 2043.
    602.2.1.7 Plastic plumbing piping and tubing.
    Plastic piping and tubing used in plumbing systems shall be listed and labeled as having a flame spread index not greater than 25 and a smoke-developed index not greater than 50 when tested in accordance with ASTM E84 or UL 723.
    Exception: Plastic water distribution piping and tubing listed and labeled in accordance with UL 2846 as having a peak optical density not greater than 0.50, an average optical density not greater than 0.15, and a flame spread distance not greater than 5 feet (1524 mm), and installed in accordance with its listing.
     
  5. Sifu

    Sifu Gold Member

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    No.
    602.2.1.5 Discrete plumbing and mechanical products in plenums. Where discrete plumbing and
    mechanical products and appurtenances are located in a plenum and have exposed combustible
    material, they shall be listed and labeled for such use in accordance UL 2043.
     
  6. rgrace

    rgrace Sawhorse

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    Condensate piping is not a discrete plumbing product.

    There are no PVC piping products that will comply with this, not without modifying the test in order to force a "pass." Next time you see an ICC report for a plastic pipe that says it conforms to ASTM E84 or UL 723, look carefully for the words "modified test" within that report.

    Condensate piping is not water distribution pipe. Water distribution pipe, along with fire sprinkler pipe (see the similar language in 602.2.1.2, "wet" only) will contain water at all times. Condensate pipe does not contain water at all times. What happened if you burn through a fire sprinkler pipe or a water distribution pipe? Water will spray everywhere until the entire system drains. Condensate piping may spill out a couple of cups of water.

    Also (gonna have to search more to find this, but I read it somewhere) the exception for "peak and average optical density" is less stringent than ASTM E84 and UL 723. From what I recall if you meet the "peak and average optical density" for your product (in other words, meet the exception), this would equate to a flame spread index greater than 25 and a smoke-developed index much greater than 50.
     
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  7. rgrace

    rgrace Sawhorse

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    Okay, I found one place where I read this. There were three code change proposals submitted to change 602.2.1.7 in the 2021 IMC; M65-18, M66-18 and M67-18. M66 was a combination of the changes proposed in M65 and M67. The reason statement was a combination of both as well. You can review this reason statement here http://media.iccsafe.org/codes/2018-2019/GroupA/CAH/IMC.pdf

    None of these proposals passed. M67-18 was brought forth as a public comment and included the UL test report referenced in the reason statement (I'm not sure why it didn't show up in the CAH link above but it is in the PCH pdf). The committee's reason for disapproval was "A product that is listed and labeled is assumed to meet the requirements of the standard with no need to state the conditions of the standard in the code text. The proposed last sentence addresses abuses in testing." Although a valid reason for disapproval, should this had been approved, it would have gone a long way in educating many code officials are out there that modified testing was being disguised as complete compliance to a test standard.
     
  8. rgrace

    rgrace Sawhorse

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  9. rgrace

    rgrace Sawhorse

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    ... and if you liked that, review this as well, very similar content

    http://hearingvideos.iccsafe.org/videos/m73-18/ Approved by committee, but disapproved during public comment based on three PC submitted (sooooo close).

    If we can't get the word out there to code officials through the code, we can at least get it to them through forums like this :) We should not be accepting modified testing. If the modification to the test were acceptable, the ASTM Committee would revise their standard to reflect this. They haven't which can be concluded that they do not agree with the modifications.
     
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  10. Paul Sweet

    Paul Sweet Sawhorse

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    I think that Rubatex, Armaflex, or similar insulations meet the flamespread and smoke limits for use in plenums. Would putting one of them around the PVC be acceptable?
     
  11. Builder Bob

    Builder Bob Sawhorse

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    Charlotte PVC piping does not meet the requirements when used as a vent pipe but appears to when filled with water. PVC piping should not be be used in a plenum, very few meet the flame/ smoke development rating requirements for use in a plenum.
     
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  12. rgrace

    rgrace Sawhorse

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    You will achieve different results if you test a pipe filled with water and when you do not. If you take a piece of plywood and test it, you will achieve different results from a dry piece of plywood and one that has been soaked in water overnight. The soaked plywood may even pass! That's a "modified" test.

    So, ASTM E84 and UL 723 require full coverage of the 20 in. x 24 ft. test area. That would be, for example, a 20 in. x 24 ft. piece of plywood. PVC and CPVC piping systems "modify" the test by placing "a single row of four 24 in. pipe lengths placed end to end, with a coupling between each length followed by a 15 ft. length of pipe either water filled or dry" (see PMG-1264 for this exact language). A single pipe is certainly not full coverage. Full coverage would not produce the desired results. Do you know why they couple four 24 in. pieces to a 15 ft. piece? As the flame in the Steiner Tunnel moves forward, the burned pieces of the pipe (24 in. coupled) separate and fall to the bottom of the chamber, extinguishing the pieces and basically rendering the test incomplete.

    UL 2846, new to 2018 IMC 602.2.1.7, is a fire test standard for plastic water distribution pipe and states in section 4.1 "There shall be no water or any other liquid in the pipe during the test." This is a test for a water distribution pipe requiring no water in the pipe during the test. Perhaps ASTM E84 and UL 723 need to revise their standards to mirror what 2846 says and include a general statement stating that other modifications to the testing process will not be acceptable.
     
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  13. jar546

    jar546 *****istrator

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    Thank you for your informative posts.
     
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  14. Builder Bob

    Builder Bob Sawhorse

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    Thank you RGrace - that certainly dove deeper into what I was alluding to......
     
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  15. rgrace

    rgrace Sawhorse

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    Sometimes I can't stanch the geek from getting out of me o_O
     
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