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Thread: Where does the P-trap go?

  1. #31
    DIY Senior Member dlarrivee's Avatar
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    In this case the code provides good instruction on how to install this system and have it work under ALLL CIRCUMSTANCES.

  2. #32
    In the Trades mtcummins's Avatar
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    Quote Originally Posted by dlarrivee View Post
    In this case the code provides good instruction on how to install this system and have it work under ALLL CIRCUMSTANCES.
    At this point I agree, in this circumstance. I think it has been determined that there is no proper and safe way to make this work (if there's a trap down there) w/o tearing it out and doing it to proper code requirements. That is a bold statement though, to assume there isn't a similar circumstance that you could do something outside of code boundaries that would function properly... But, that's moot at this point, as I conceded in my previous post that I think the ONLY solution in this circumstance is to dig it out and do it to code.

    However, if for example this had been roughed with everything to code except the trap arm on the tub was 62" long, at which point a proper vent was installed, would you seriously tell this guy to tear out all his concrete to move the vent 2" closer to the trap? That was my point, not that it should be set up wrong in the first place (or anything of the sort), but sometimes a situation calls for doing (or leaving) something safe, but slightly outside of code parameters. This is not one of those situations, it seems.

  3. #33
    DIY Senior Member dlarrivee's Avatar
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    If it was vented it wouldn't be a problem. I'm not sure what you want me to say? Moving a vent over 2" is not the same as exempting it from your design...

  4. #34
    Test, Don't Guess! cacher_chick's Avatar
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    The tub rough in has no vent. There is an existing stack, which could be continued upwards. As an alternative, a wye could be cut into the horizontal drain outside, and the vent could be run up a chase in or on the outside wall. Either way, if a vent is not added, it does not meet any plumbing code, which is the MINIMUM requirement for a safe and proper installation.
    Would you have your mother driving a car with only one lug nut holding on the wheels? It makes no sense to hope something "might work" when there are minimum standards already in place.

    This type of work requires a permit and inspection to ensure that these minimum requirements are met. It is not in anyone's best interest to make recommendations or suggestions that circumvent a safe and legal installation.

  5. #35
    In the Trades mtcummins's Avatar
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    And what do you want me to say that I haven't said already... I AGREE WITH YOU... this needs to be torn out and redone to code... do I have to spell it out more clearly?

    You made a statement that code is to be followed in all circumstances. This example was a completely different situation where I would say that its not critical to do so. That has no bearing on this instance, only an example of how code-to-the-letter is not always the answer in every circumstance.

    Once again, I'm agreeing with you and the others that this cannot be worked safely without tearing it apart (assuming a trap is down there). Once you've done that, there is absolutely no reason to not bring it up to code, and I fully advocate doing it to proper code.

  6. #36
    Test, Don't Guess! cacher_chick's Avatar
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    Quote Originally Posted by mtcummins View Post
    And what do you want me to say that I haven't said already... I AGREE WITH YOU... this needs to be torn out and redone to code... do I have to spell it out more clearly?
    Who said I was talking to you? <grin>

  7. #37
    In the Trades mtcummins's Avatar
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    Quote Originally Posted by cacher_chick View Post
    Who said I was talking to you? <grin>
    Haha, that happens to me all the time... I reply w/o using a quote, and while I'm typing another post gets in between. Sorry, wasn't meant for you

  8. #38
    DIY Junior Member blackm3sedan's Avatar
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    Quote Originally Posted by dlarrivee View Post
    The problem comes when somebody flushes the toilet while the faucet is also running at the sink (or the sink was full and is draining)...

    99/100 it would be fine, but I'd prefer it to be impossible to siphon the trap, not a 1/100 odds that it will.
    You're correct. My assumption was that only one person was using the bathroom at a time.

    However, I think there are some flaws in your assumption. You're assuming that the water from the sink is filling the entire 2" drain line. Since the drain from the sink is only 1.25" diameter, I don't think this is possible without adding pressure to the sink drain to get the equivalent flow. It's plausible that there is enough room in the 2" drain line for the water and enough air to fill the vacuum.

    Even without assuming there's still a direct path to atmosphere, the water from the sink is still filling the void behind the slug of water from the toilet, thus eliminating the vacuum and preventing the siphon. When the water from the sink is finished draining, it will be vented to atmosphere, thus eliminating the vacuum also.

    With the exception of possibly not meeting the 24" maximum vertical separation between the trap and the drain (assuming there is a trap at the bottom of the riser), I haven't seen any evidence of it not meeting. In my interpretation, I think it meets the code for a wet vent, although I am obviously no expert. It was installed by a licensed plumber and it has been inspected by the county plumbing inspector with signatures. Neither of those statements means that system was installed correctly.

    I've attached links to the Florida Building Code section on plumbing vents and plumbing traps, if someone wants to spend more time than I would ever ask to to help me interpret the code.

    https://docs.google.com/open?id=0B95...M1NDlhYjNiNjFh

    https://docs.google.com/open?id=0B95...ViN2M3ZTZiNzFj
    Last edited by blackm3sedan; 12-09-2011 at 04:33 AM.

  9. #39
    DIY Senior Member dlarrivee's Avatar
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    I'm not interested in fishing through documents to prove a point.

    We all know it isn't done properly, it's simply speculative to come to some conclusion that it "will work because"... It doesn't meet any code I've ever read.

  10. #40
    DIY Junior Member blackm3sedan's Avatar
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    Quote Originally Posted by dlarrivee View Post
    I'm not interested in fishing through documents to prove a point.

    We all know it isn't done properly, it's simply speculative to come to some conclusion that it "will work because"... It doesn't meet any code I've ever read.
    I never asked you specifically to fish through all 3 pages of the plumbing trap code. I provided the code in case someone wanted to point to it and say that it specifically is not done per this statement in the code.

    I don't believe that 'we' know it isn't done properly. My licensed plumber and my inspector believe that it is done per code. I provided evidence that the trap for the tub is still being vented and I don't believe anyone has proven otherwise. I'm not saying that it is the best way, but I don't think it violates any part of the plumbing code.

    I also don't believe the laws of physics are 'simply speculative'. I would bet that any properly written code is based on them.

    Your contribution to this thread has been invaluable. Thank you.

  11. #41
    DIY Junior Member blackm3sedan's Avatar
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    I almost forgot, I have visually verified that there is indeed a trap at the bottom of the riser for the bathtub. So I will be connecting the tub to the riser directly, without a vent or trap.

    Thank you to those that provided helpful comments and insights. You got me pointed in the right direction. It's very much appreciated.

  12. #42
    Moderator & Master Plumber hj's Avatar
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    The Bornoulli Principle uses "velocity" NOT volume to create the "negative pressure". I have a customer who had a pump installed for a room addition. They connected it to the 2" vent for the toilet. EVERY TIME the pump operates the water flowing past the toilet's 3" connection "SUCKS" the water out of the toilet, EVEN though the 3" line is NOT full of water. I love it when people tell me I do NOT know what I am talking about, because that just affirms that I do. "Wet venting" has NOTHING to do with whether the toilet is the first fixture or the last one. IT depends on HOW ALL the piping is arranged, and it is on a "fixture by fixture" basis. In fact, you could have a "lot" of wet venting, and NOT involve the toilet at all.
    Licensed residential and commercial plumber

  13. #43
    In the Trades mtcummins's Avatar
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    Wow, thats some impressive suction... hj, would you mind posting a simple sketch of this setup? I'm just curious, and not sure I fully understand the layout you described. Thanks.

    I think there's no more point in trying to convince this guy, he's obviously made up his mind. It'll be his problem if/when his bathroom is full of sewer gases.

    The NASA guy thinks he understands it better than the life-long pros. I'd still like to hear that engineer-speak description of the overflow functioning as a vent though... that cracked me up

  14. #44
    DIY Senior Member dlarrivee's Avatar
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    I would fix it for reasons other than sewer gas, like for example, peace of mind, pride of work.

    I couldn't cover up a hack job with a straight face and call it good, call me crazy.

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