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Condensate problem

Hi Mike.If the evap drain fitting is on the "positive" side, then the air pressure blowes the water away from the drain fitting so the air can escape ,building up the water in the pan resulting in condensate "blow-over" out of the pan and into the duct,or down into the furnace/air handler. Shutting down the blower lets all that backup water drain out.Cleaning the trap on a seasonal inspection gets rid of all that "stuff" out of the drain,so no problem .Enjoy!

Comments

  • Robert O'Brien
    Robert O'Brien Member Posts: 3,272
    Condensate problem

    I don't do CAC,strictly heating,but on a heating call today the cust. asked me to look at the airhandler because the condensate wasn't draining properly. The line was clear but wasn't draining,it only drains when blower is off otherwise it dumps on floor from bottom of airhandler.The blower is creating a vacuum and preventing condensate from draining.Air Filter and Coil are clean,the return is flex and is poorly installed. Could the restriction in return cause this? If not,what?

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  • don_182
    don_182 Member Posts: 69
    Hello Robert

    Is this a pulled thru coil? And does it have a p-trap on the drain line?
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,272


    Yes,has trap about 18" from Airhandler,between trap and airhandler is a tee with a 6" nipple installed vertically into bull of tee.I assume this is functions as a vacuum breaker.TIA

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  • jim lockard
    jim lockard Member Posts: 1,059
    Lose the tee

    Robert do not put a vent between the Air handle and the trap. The vent belongs on the out bound side of the trap. Check to make sure your pipe is not sagging (so as not to double trap). Make sure your trap is nice and deep about 3 to 3.5 inches from in to out. Best Wishes J,Lockard
  • don_156
    don_156 Member Posts: 87
    I agree

    The T kind of defeats the purpose of having the trap.
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,272


    I didn't install this,would the Tee cause the blower to prevent condensate from draining? TIA

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  • JimmyJam
    JimmyJam Member Posts: 78


    Yes! it will only drain out the pan when blower shuts off due to negative pressure created by blower, the trap when filled with water prevents this.
    I think you could just cap the top of the vent tee, run the A/C and hold your hand over the outlet of the drain, the trap will fill and all will be good!

    71Gibby
  • Techman
    Techman Member Posts: 2,144
    Condensate Traps

    Evening! As Jim said, and don't forget to clean out the trap.You need a trap an ALL evap,s ! Either "pull thru" or "blow thru" a trap is needed.
  • Empire_2
    Empire_2 Member Posts: 2,343
    Trap...

    You can leave the "T" but make sure you cap it. This is probably used as a clean out. Must be capped when A/C is in operation.

    Techman, why do you state that all A/C coils need a trap either on the neg. side or pos. side? If it is code then yes I agree, but traps are another way to collect crap and need to be frequently cleaned out. Positive side drainage does not need a trap unless like I said it happens to be a code in your township or state....

    Mike T.
  • Empire_2
    Empire_2 Member Posts: 2,343
    Good point Techman.

    Makes sense to me...;-)
  • Jeff Lawrence_24
    Jeff Lawrence_24 Member Posts: 593
    nearly the exact discussion

    I had a discussion with a home inspector. He told me that every condensate connection was supposed to have a trap and the local codes required it. Not long after, I asked the county HVAC inspector about it and he said that the positive pressure systems did not have to have a p-trap, only negative pressure systems. He also told me that he wouldn't fail someone that had a p-trap on the PP system.

    Whenever I do a cooling system check up, I try to use my wet-vac outside the house tomake sure the condensate line is clear. I did one a week or 2 ago that filled my 6 gallon wet vac halfway up with water and slime.

    I also suggest to customers that they pipe the water away from the house, as the installers usually just dump the water whereever they can, as long as it's outside. If the HO decides to extend the pipe underground and/or a far distance, I suggest a tee betweem the house and the 'remote' piping in case the line becomes stopped up.
  • Brad White_97
    Brad White_97 Member Posts: 15
    Good Discussion

    You all nailed a common problem and well.
  • Techman
    Techman Member Posts: 2,144
    Traps

    One more before before "out the door".Is the distance from the A/H to the trap critical? Say 4' maybe 8'?Enjoy!
  • don_182
    don_182 Member Posts: 69
    No

    Hello Techman.I know a lot of guys that installed the trap on the outside of the home and they never have a problem.

    I see the depth of the trap being more important then the distance.

    Its going to be a hot one for all this week...drink lots of water everyone.
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    Height Matters

    Length is not super-critical within reason. (Go too far and the curvature of the earth may become an issue, but would it ever form a trap? ... Ponderable thought I did not need right now..) :O)

    Key is trap depth: The trap seal should equal at least the pressure at point of connection plus one inch.

    EDIT: Pressure expressed -how conveniently!- in inches of water gauge.


    Some use total pressure plus an inch to be conservative. Sometimes this is not possible or if on-grade, you have to make a pit. We do this on larger commercial/institutional systems.

    One technique I picked up: All calculations aside, reality is reality... Make the trap with an adjustable compression slide -like a trombone- so you can adjust the depth to the actual conditions. Run the unit full tilt and slide it until you get flow. Lock in place. Also connect with a union for quick blow-out. If outdoors, good to do this before winter freezes destroy your traps.

    Brad
  • Empire_2
    Empire_2 Member Posts: 2,343
    Just a thought

    While were on the sublect,..Every once in a while I run into a double trap.. Dont aks me why, but I think the guy's before thought that if 1 works 2 must be better. This will not work due to the fact that the second trap will create a neg vac. on the first and never reliably drain out.;-)

    Mike T. ANd Yes it is HOT!!!!! I love it.;-)
  • jim lockard
    jim lockard Member Posts: 1,059
    Some times

    Mike what you see as a double trap may be a 3.5 inch deep trap at the evap coil then a vent, then just before the drain pipe exits the home (Mostly attics) you will see a running trap(about a 1 inch dip) or a seal. that is done to keep bees and bugs from entering the attic from the drain pipe. As for freezing traps we have seen a lot in attics yet none have froze and broke. Oh and 2 traps in a row without a vent will not drain. Hope this helps J.Lockard
  • Empire_2
    Empire_2 Member Posts: 2,343
    Jim

    I have seen that before. As long as you have the vent after the first trap, it will work. I never had a problem with the bee's though. I'm sure it could happen. Also, with extra long slightly pitched horizontal runs, I have put in an extra tee for a vac. breaker.

    Mike T.
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