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Thread: Trap Primer

  1. #1
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    Trap Primer

    Evening, was wondering what does anyone know about the code about trap primers, I was told that a condensing drain line going into a trap had to have a trap primer installed. I haven't seen anything like this before, nor has anyone else I have asked about.

  2. #2
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    A trap primer is a plumber thing in my area. I don't see why it would even apply to hvac unless for some reason the drain has been tied into the house sewer system. If that is the case good luck.

  3. #3
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    Quote Originally Posted by dcweb View Post
    Evening, was wondering what does anyone know about the code about trap primers, I was told that a condensing drain line going into a trap had to have a trap primer installed. I haven't seen anything like this before, nor has anyone else I have asked about.
    It would be rare that any AHJ would allow you to tie directly into a sanitary drain for condensate disposal. A trap primer is to maintain a wet trap to prevent sewer gas from entering a space. Used in commercial applications such as bathroom floor drains or areas of negative pressure where the trap can evaporate and loose its seal

  4. #4
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    Quote Originally Posted by second opinion View Post
    It would be rare that any AHJ would allow you to tie directly into a sanitary drain for condensate disposal. A trap primer is to maintain a wet trap to prevent sewer gas from entering a space. Used in commercial applications such as bathroom floor drains or areas of negative pressure where the trap can evaporate and loose its seal
    I agree. That's why I said good luck if this is the case. Getting it re done properly is going to be a pita. Wouldn't be the first time I've seen it done though.

  5. #5
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    any trap (hooked to the sewer)that may have sparse use, needs a trap primer, never seen one required for your setup, but if its the only thing this trap/drain serves, in down parts of the year (Meaning no use) the trap would dry up, and let sewer gas into the building. (Trap primer or really vegetable oil would work.... maybe not to your code)

  6. #6
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    they want the trap primer installed in the attic crawl space

  7. #7
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    you have a floor drain in the attic? (in Maine?)

  8. #8
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    the funny thing is I ask to show me in the code book and they wont, say I should know this

    garychance if I did it would be easier

  9. #9
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    pretty messed up if they will not show you, This is a plumbing code requirement as its the plumbing system, you just terminate to it indirectly. If a primer is required its the plumbers deal.

  10. #10
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    Your condensate discharge must be through an air gap into an approved drain system just as Gary said. The plumbing code and plumber determine that point. You're not going to put a trap outdoors (attic) where it can freeze. Thus you would need to discharge down into the conditioned space and find a suitable drain there. Just put it over the shower stall [grin].

    Some AHJs recognize the difference btw air conditioning condensate vs. flue gas condensate and will both make allowances or be more strict. We're seeing more and more concern about the acidic flue gas condensate and requiring pH buffers before discharge. This means a maintenance item replacing the media as needed. Gone are the days of drilling a hole in the basement floor and discharging into the soil.

    With attic air conditioners, most still discharge either directly outside down the wall or let it drip to the ground. Others will discharge into the rain gutter but it ends up the same place. FYI, discharge against a wall will ruin it. Another method is to run a DWV stand pipe up into the attic with an open bell termination where the condensate can discharge by air gap into it. The fluid falls down into the building where it is trapped below. Discharge piped directly into DWV pipes is a big red flag. It used to be contractors were allowed to loop the drain tubing making a trap that then is run directly into a hole drilled into the DWV and sealed with silicone caulk. This is not approved and usually fails.

    If an AHJ refuses to show you a specific reference in a code book or list of local ordinances that were voted into law then he has no legal right and you do not have to comply. You can appeal the issue to your state board. The ICC has been very pro active in shutting down rogue AHJs who think they're god and try to legislate from their desks. Submit a request for the specific code sections IN WRITING and Cc his boss. Politely state you are attempting to comply with the law but since they are making a ruling you deserve to know what they are basing it upon. If you still get nowhere, take it to the ICC if you're clearly in the right. Just do your homework.

    Now, having said all that, let's have a show of hands how many here actually own a copy of their relevant building and mechanical code books? [me] Folks, it is the law and one the public relies on YOU to know as a professional. If you don't have the code books, you cannot stay fresh on the code.

  11. #11
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    The condensate was run threw a 1 1/2 trap that was in the attic, with a 1 1/2 x 3 I think adaptor and then drips into it, so there is a trap in the sewer line, he is saying that the trap in the attic needs to have a trap primer installed on it

  12. #12
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    Quote Originally Posted by dcweb View Post
    The condensate was run threw a 1 1/2 trap that was in the attic, with a 1 1/2 x 3 I think adaptor and then drips into it, so there is a trap in the sewer line, he is saying that the trap in the attic needs to have a trap primer installed on it
    If its hooked to the sewer, and since its not going to be used year round, your code probably calls for it. But this would still be the plumber who has to do it. (how does it not freeze in the winter?)

  13. #13
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    Sounds like a job for the plumber - not you.

    The trap primers that I've experienced required a fresh water line run to that location... fed typically to a solenoid that's on a timer that allows it to run a bit of water into the trap at specific time intervals.

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