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  1. #1

    what are the rules or code for ac condensate drain traps

    my Carrier central ac is about 4 yrs old. the main drain comes off the coil into a trap and to the floor hole. the secondary or overflow drain threaded hole is plugged with a red plastic plug.

    should the overflow also be opened and trapped and let to drain or doesn't this get done most often ?

    what is the reason for the main drain being trapped, code ?? why is this nessassary or isnt it ?

  2. #2
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,189
    Code says it needs to be trapped and piped.

    It is very rarely done correctly.

    Some local authorities have started requiring it.
    Perhaps you should have read the instructions before calling.

  3. #3
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,569
    The primary on an air handler is trapped due to the negative pressure on the drain. It allows the drain to drain. It is also trapped to prevent smell from getting into the airstream, just like a trap in a sink or toilet. It is nice to have the secondary on the air handler hooked up to the secondary pipe leaving the house or a float switch installed on it to facilitate it draining easier when the primary does get plugged. I've seen it many times where this is blocked, the primary gets clogged and water flows all over in the air handler, flows to the end of where the secondary drain end and drops into the sheetrock and ruins it.

  4. #4
    I wonder if i should have the secondary piped and trapped too ? no water would be in the secondary though as its only an overflow so the trap would be dry.

    i have never had the primary plg,i use white pleated filters and the coil area stays very very clean. you would think even without a trap the water would gravity flow, i have to say i have seen more not trapped than i have trapped.

    this doesn't mean its right though

  5. #5
    Join Date
    Apr 2008
    Location
    Upstate New York
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    799
    I have the same exact thing on mine. I had a new Rheem furnace put in and before this my drain just came out with 3/4" pvc and 90 to the floor and went to the floor drain and never a problem for 3 years without a trap.

    Now they cut the pcvc at the furnace and put in a trap and ran it down and ted into the furnace condensate drain and ran to my floor drain.

    I too have the red plug in the upper overflow hole. I have looked in at my coil and it is spotless clean. I have an open T after the trap on the condensate.

    Should I pipe the overflow that is plugged or just leave alone what I have now ??

  6. #6
    Join Date
    Jul 2006
    Location
    NW burbs of Detroit
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    6,058
    Quote Originally Posted by cvcman View Post
    I have the same exact thing on mine. I had a new Rheem furnace put in and before this my drain just came out with 3/4" pvc and 90 to the floor and went to the floor drain and never a problem for 3 years without a trap.

    Now they cut the pcvc at the furnace and put in a trap and ran it down and ted into the furnace condensate drain and ran to my floor drain.

    I too have the red plug in the upper overflow hole. I have looked in at my coil and it is spotless clean. I have an open T after the trap on the condensate.

    Should I pipe the overflow that is plugged or just leave alone what I have now ??
    Hwy big guy, you're hijacking this gent's thread. Please read rules.

  7. #7
    Join Date
    Jul 2006
    Location
    NW burbs of Detroit
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    6,058
    Quote Originally Posted by rangerr91 View Post
    I wonder if i should have the secondary piped and trapped too ? no water would be in the secondary though as its only an overflow so the trap would be dry.

    i have never had the primary plug,i use white pleated filters and the coil area stays very very clean. you would think even without a trap the water would gravity flow, i have to say i have seen more not trapped than i have trapped.

    this doesn't mean its right though
    The secondary drain is a precaution to let you know the main is plugged.
    It's used for horizontally positioned air handlers and furnaces installed in attics
    a closet applications.

    It sounds like you have a furnace with the cooling coil on top, so in your case the secondary drain is not used..


    Just an aside..on up flow furnaces the drain is under positive pressure, so why the need for a trap?

  8. #8
    Join Date
    May 2003
    Location
    Needmore, WV
    Posts
    56
    Quote Originally Posted by hvaclover View Post
    The secondary drain is a precaution to let you know the main is plugged.
    It's used for horizontally positioned air handlers and furnaces installed in attics
    a closet applications.

    It sounds like you have a furnace with the cooling coil on top, so in your case the secondary drain is not used..


    "Just an aside..on up flow furnaces the drain is under positive pressure, so why the need for a trap?"
    "Cuz when the fan stops blowing it's not under pressure and since the drain is tied into the grey/black water drain system when there's wind flow across a structure this can create a negative pressure inside the structure which would draw methane, a flammable gas, into the structure if there were no j-Trap or condensate pump (unpredictable) as there is on my house. In my own residence, the builder substuted an unpredictably reliable $70 condensate pump instead of $5 worth of drain materials 1 1/2 feet from the furnace- the A-Coil (A/C) equipped condensating LPG (unused) hi-efficiency furnace replete with dehumidifier is all tied into one condensate pump. This would be the plumbing equivalent of "Shi'ite flows uphill" school of plumbing. So your j-trap is a last line of defense against HVAC "boneheads"."

  9. #9
    Join Date
    May 2003
    Location
    Needmore, WV
    Posts
    56
    it
    Quote Originally Posted by hvaclover View Post
    The secondary drain is a precaution to let you know the main is plugged.
    It's used for horizontally positioned air handlers and furnaces installed in attics
    a closet applications.

    It sounds like you have a furnace with the cooling coil on top, so in your case the secondary drain is not used..


    "Just an aside..on up flow furnaces the drain is under positive pressure, so why the need for a trap?"
    "Cuz when the fan stops blowing it's not under pressure and since the drain is tied into the grey/black water drain system when there's wind flow across a structure this can create a negative pressure inside the structure which would draw methane, a flammable gas, into the structure if there were no j-Trap or condensate pump (unpredictable) as there is on my house. In my own residence, the builder substituted an unpredictably reliable $70 condensate pump instead of $5 worth of drain materials 1 1/2 feet from the furnace- the A-Coil (A/C) equipped condensating LPG (unused) hi-efficiency furnace replete with dehumidifier is all tied into one condensate pump. This would be the plumbing equivalent of "Shi'ite flows uphill" school of plumbing. So your j-trap is a last line of defense against HVAC "boneheads"." I put an Zoeller A-Pack alarm on this un-drained upflow of an atrocity. All I have to say is: "If I have to put an alarm on your work, you already done something wrong..."

  10. #10
    Join Date
    May 2008
    Location
    North Texas
    Posts
    105
    Anyway, if on International Residential Code see M1411.3; or if on Uniform Mechanical Code see 310.1-.5.

  11. #11
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
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    14,915
    Quote Originally Posted by hvaclover View Post
    Just an aside..on up flow furnaces the drain is under positive pressure, so why the need for a trap?
    If you had a 3/4" round hole in a duct, what would you do with it?
    If more government is the answer, then it's a really stupid question.

  12. #12
    Join Date
    Apr 2008
    Location
    Upstate New York
    Posts
    799
    Mark and Mike thanks you guys make sense

  13. #13
    Join Date
    Jul 2006
    Location
    NW burbs of Detroit
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    Quote Originally Posted by mark beiser View Post
    If you had a 3/4" round hole in a duct, what would you do with it?
    Don't get what you mean.

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