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  1. #14
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    Quote Originally Posted by everyman View Post
    The ac condensate line in my unit is blowing (or leaking) air into the condensate pump well, causing positive pressure inside the well. For the furnace condensate line, there would be back pressure in the well. I was concerned that this back pressure will cause problems for the furnace condensate drainage.
    I'm not sure I can state the solution differently...
    The TRUE highest cost system is the system not installed properly...

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  3. #15
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    Mar 2008
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    Quote Originally Posted by vstech View Post
    I'm not sure I can state the solution differently...
    I agree with you that it's correct to have a p-trap there, based on my limited analysis of the system. I'm having second thoughts about replacing my 23 years old central AC, since it works ok. Do you think it's cost effective to have a p-trap retrofitted to my existing AC?

  4. #16
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    Well... without it, a percentage of your conditioned air is dumping outside... thus drawing in unconditioned air elsewhere in the house. A double hit in efficiency.
    The TRUE highest cost system is the system not installed properly...

    Find a HVAC-Talk Contractor by clicking here

    Do you go to a boat repairman with a sinking boat, and tell him to put in a bigger motor when he tells you to fix the holes?

    I am yourmrfixit

  5. #17
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    Thread Starter
    Quote Originally Posted by vstech View Post
    Well... without it, a percentage of your conditioned air is dumping outside... thus drawing in unconditioned air elsewhere in the house. A double hit in efficiency.
    Extending the condensate line an inch below water would be cheaper than retrofitting a p-trap. What problems would i have using the condensate pump well as a trap? You have to remember that there is a vent on the line upstream so the conditioned air is going to be dumping outside (but to a lesser extent) even if there is a trap.

  6. #18
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    May 2006
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    Philadelphia, PA
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    Quote Originally Posted by everyman View Post
    Extending the condensate line an inch below water would be cheaper than retrofitting a p-trap. What problems would i have using the condensate pump well as a trap?
    As debris and other gunk builds the drain will be blocked.

    Somewhere around pg 18 of the install manual shows the furnace drain. It must be vented also. Time to get the installer back to make a few corrections.
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  7. #19
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    Mar 2008
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    Thread Starter
    Quote Originally Posted by comfortdoc View Post
    As debris and other gunk builds the drain will be blocked.
    I could say the same for the p-trap, which can trap gunk and debris.

  8. #20
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    Quote Originally Posted by everyman View Post
    Extending the condensate line an inch below water would be cheaper than retrofitting a p-trap. What problems would i have using the condensate pump well as a trap? You have to remember that there is a vent on the line upstream so the conditioned air is going to be dumping outside (but to a lesser extent) even if there is a trap.
    that is why the trap needs to be BEFORE any vent.

    the drain should exit the coil, and IMMEDIATELY be connected to a trap, then AFTER the trap a vent can be installed.
    The TRUE highest cost system is the system not installed properly...

    Find a HVAC-Talk Contractor by clicking here

    Do you go to a boat repairman with a sinking boat, and tell him to put in a bigger motor when he tells you to fix the holes?

    I am yourmrfixit

  9. #21
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    Mar 2008
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    Quote Originally Posted by vstech View Post
    that is why the trap needs to be BEFORE any vent.

    the drain should exit the coil, and IMMEDIATELY be connected to a trap, then AFTER the trap a vent can be installed.
    Thanks for the clarification.

  10. #22
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    Mar 2008
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    From anther site http://www.eng-tips.com/viewthread.cfm?qid=265115:

    "If the discharge of the line from the coil drain pan to the pump's sump is always below the water level in the pump, and the depth of water in the sump is sufficient, then technically that will work as a trap."

    "If you pipe to a condensate drain sump, have the inlet pipe drop at least 4" out of the unit and drain a couple inches below the level of the water maintained in the sump."

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