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Condensate Drain Vent

I hate when that happens!


  • ETrabby
    ETrabby Member Posts: 2
    Condensate Drain Vent

    Have a condensate drain on an AHU that does not seem to work. Unit is under negative pressure. Checked pitch on drain/unit - OK. Drain does not appear to be plugged. Someone had plugged the airvent on the drain. I pulled the plug on the vent. The drain still isn't draining. What gives?
  • don_156
    don_156 Member Posts: 87

    it a p trap or a running trap? And is the vent before the
    trap or after the trap?

    Also I have seen lots of drain under the house that become bow and keeps the water from draining.

    And last but not least,what kind of static pressure are you seeing?

  • ETrabby
    ETrabby Member Posts: 2

    vent is after the trap, but I'm not sure what you mean by P or running
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    AH Configuration

    Can you please provide some more info?

    Just to clarify for me and others that may be reading this, assume you are traveling to the air handler from the return grill. Please list the order in which you encounter the following system components:

    a) Air handler blower

    b) Evaporator coil

    c) Primary drain fitting

    Also, is the air handler vertical or horizontal and where is it located? Where is the drain line leading (to the outside or to a condensate pump)?
  • Empire_2
    Empire_2 Member Posts: 2,343
    Long horiz. runs

    Keep in mind that even though you have a trap on the begining of the system, you must break the vacuume on the remaining run as it exceeds practical limits. Exmp: on a 25 ' run (horizontal) for a Space pac unit I have 2 tee's in the line to vent my line as it goes further and further down the line. As water fills the line you must break the vacuume to allow it to proceed any further. It's almost a trial and error process, but you can get the gist of it as you go. try this and see what happens.. Let me know what you find.
  • Josh_5
    Josh_5 Member Posts: 1
    Drain line

    Hate to state the obvious, but wondering if this problem is occuring on the first run of the year. If so, try shutting the unit down. This will allow the trap to fill. Once the pan has drained, start the runit again. Also, make sure the overflow wasnt' piped as the primary drain by accident.
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