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  1. #1
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    Default TPR Discharge with Pex fittings

    I see Pex fittings used to elbow the termination all the time and write it up based on reducing the size of the discharge pipe, but I have scanned numerous forums and articles on the internet and cannot find mention of it.

    To make sure I am understanding it and that I am not writing up something that really is correct...

    Anything, that reduces the interior diameter of the pipe is a violation of 2804.6.1. Right?

    3. )Not be smaller than the diameter of the outlet of
    the valve served and shall discharge full size to the
    air gap.

    Secondly, if I am reading #14 properly, if the valve is 3/4", then the Pex should be 1". Correct?

    14. Be one nominal size larger than the size of the
    relief-valve outlet, where the relief-valve discharge
    piping is constructed of PEX or PE-RT tubing.
    The outlet end of such tubing shall be fastened
    in place.

    Also, do any of you ever see the termination fastened in place?

    Just wanting to do a good job here. Thanks, Bruce.

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    Bruce Thompson, Lic. #9199
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    Home Inspections in the Tyler and East Texas area

  2. #2
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    Default Re: TPR Discharge with Pex fittings

    The key is in the wording ... all pipe sizes are "nominal" ... bet you haven't seen a 2x4 lately either ...

    Think of CPVC ... it is quite a bit smaller in actual dimensions - but it is still 1/2" and 3/4" "nominal".

    PEX is permitted as the T&P relief valve discharge pipe.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  3. #3
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    Default Re: TPR Discharge with Pex fittings

    Quote Originally Posted by Jerry Peck View Post
    The key is in the wording ... all pipe sizes are "nominal" ... bet you haven't seen a 2x4 lately either ...

    Think of CPVC ... it is quite a bit smaller in actual dimensions - but it is still 1/2" and 3/4" "nominal".

    PEX is permitted as the T&P relief valve discharge pipe.
    I've understood that PEX is permitted and based on what you're saying about "nominal" (at least I think I understand where you're going with this), then the fittings which are physically smaller ARE permitted....assuming they are 3/4" nominal.

    Is that what you're saying?

    Bruce Thompson, Lic. #9199
    www.TylerHomeInspector.com
    Home Inspections in the Tyler and East Texas area

  4. #4
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    Default Re: TPR Discharge with Pex fittings

    14. Be one nominal size larger than the size of the
    relief-valve outlet, where the relief-valve discharge
    piping is constructed of PEX or PE-RT tubing.
    The outlet end of such tubing shall be fastened
    in place.
    Where are you getting this from?
    Everything I read stops at #13

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  5. #5
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    Default Re: TPR Discharge with Pex fittings

    Quote Originally Posted by JB Thompson View Post
    ... then the fittings which are physically smaller ARE permitted....assuming they are 3/4" nominal.

    Is that what you're saying?
    Precisely what I am saying.

    The inside diameter of the piping varies even within copper types, soft drawn, hard drawn, and annealed - it is the outside diameter which remains constant so they all fit the same fittings.

    The inside diameter of PVC is even smaller (walls are thicker) and CPVC is even smaller than PVC (even the outside diameter is smaller), yet all the different types have the same IP (iron pipe) sized threaded fittings, 3/8", 1/2", 3/4", etc. ... so let's consider the inside diameter of iron pipe with the same thread fitting size - the walls of iron pipe are thicker than almost any other pipe, except maybe PVC, and 3/4" CPVC looks like it could almost fit inside of 3/4" hard drawn cooper ... all the same nominal size and all fit and thread into the same threaded fittings.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  6. #6
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    Default Re: TPR Discharge with Pex fittings

    Quote Originally Posted by Jim Luttrall View Post
    Where are you getting this from?
    Everything I read stops at #13
    2015 IRC

    - - - Updated - - -

    Quote Originally Posted by Jerry Peck View Post
    Precisely what I am saying.

    The inside diameter of the piping varies even within copper types, soft drawn, hard drawn, and annealed - it is the outside diameter which remains constant so they all fit the same fittings.

    The inside diameter of PVC is even smaller (walls are thicker) and CPVC is even smaller than PVC (even the outside diameter is smaller), yet all the different types have the same IP (iron pipe) sized threaded fittings, 3/8", 1/2", 3/4", etc. ... so let's consider the inside diameter of iron pipe with the same thread fitting size - the walls of iron pipe are thicker than almost any other pipe, except maybe PVC, and 3/4" CPVC looks like it could almost fit inside of 3/4" hard drawn cooper ... all the same nominal size and all fit and thread into the same threaded fittings.
    I've always understood the O.D. and I.D. differences, but apparently I've never grasped the word "nominal". Thanks for the clarification.

    Bruce Thompson, Lic. #9199
    www.TylerHomeInspector.com
    Home Inspections in the Tyler and East Texas area

  7. #7
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    Default Re: TPR Discharge with Pex fittings

    Quote Originally Posted by JB Thompson View Post
    2015 IRC.
    The best thing that new section does is provide a stated requirement to anchor the end of the PEX ... I have used the spacing of supports in the past.

    The worst thing that new section does is ignore the fact that there are other piping types which are even smaller than PEX - such as CPVC (the end of which also needs to be anchored).

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  8. #8
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    Default Re: TPR Discharge with Pex fittings

    I had not seen the requirement of
    upsizing of PEX and securing the end.

    Of course I almost never see PEX on TRP drains anyway.
    I guess that rules out the ready made PEX down tubes that they sell at the big box stores.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

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