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  1. #1
    Join Date
    Jun 2009
    Location
    Pompano Bch, S Fla
    Posts
    57

    Water dripping off face of a new coil.

    Hello everyone, I finally have a question that I feel is worthy of starting a new thread. We just put in a new syetem at a school. 15 ton split, I forgot to record model #'s but looked online and pretty sure it's a Rheem RHGM 15 ton a/h which is a slant coil) with two RPWL 7.5's. We had a leak in one of the circuits that was discovered at end of day so we left one condenser running while vacuuming the other overnight. Returned today and (this is where it gets interesting) found that water was dripping off about halfway down the evap coil and missing the drain pan completely. Boss thought it might have something to do with only one circuit running but it still happens with both condensers running. The building went w/o air for 3 weeks and there's ALOT of condensation but it still doesn't seem right. Never seen anything quite like this. I'm more of a resi guy so any thoughts would be appreciated. Thanks in advance

  2. #2
    Join Date
    Apr 2012
    Location
    winnipeg
    Posts
    1,330
    it appears you have high velocity..... just a thought
    it was working.... played with it.... now its broke.... whats the going hourly rate for HVAC repair

  3. #3
    Join Date
    Aug 2012
    Location
    Palmyra, Missouri, United States
    Posts
    224
    Quote Originally Posted by Pete954 View Post
    Hello everyone, I finally have a question that I feel is worthy of starting a new thread. We just put in a new syetem at a school. 15 ton split, I forgot to record model #'s but looked online and pretty sure it's a Rheem RHGM 15 ton a/h which is a slant coil) with two RPWL 7.5's. We had a leak in one of the circuits that was discovered at end of day so we left one condenser running while vacuuming the other overnight. Returned today and (this is where it gets interesting) found that water was dripping off about halfway down the evap coil and missing the drain pan completely. Boss thought it might have something to do with only one circuit running but it still happens with both condensers running. The building went w/o air for 3 weeks and there's ALOT of condensation but it still doesn't seem right. Never seen anything quite like this. I'm more of a resi guy so any thoughts would be appreciated. Thanks in advance
    Im assuming that the drain line leaving the air handler does not have a proper trap installed.

  4. #4
    Another thought on this. Several manufactures have had similar problems. (Carrier, Trane, ect) Air flow can be the culprit but most likely the "wet-ability" of the coil surface causing water to not to run off into the drain properly. Check to see if the evaporator coil is level in case. Clean the coil with a good evaporator cleaner. Don't use home made stuff not made to clean evaporators. (Dish soap, dishwasher detergent, and grandma's special lineament. These could make it worse or even impede air flow) If a good cleaning does not work there are coil coating solvents made for this. Generally referred to as "wetting" agents. Trane use to sell one, this coating allows water to cling to fins until it reaches the drain pan. If all else fails some companies like Carrier use to make "Drip-a-lators" a spare part that has angled pieces of right angle fins about 3/4" apart and had little troughs in them to let them catch the dripping water off the middle of the coil and drain into the drain pan. Just remember anything you put in the airflow will change your external static and might make the situation worse. A final solution I found when the water was dripping off after the blower shut off, is to wire a time delay relay to the blower and have it run 5-10 minutes after the compressor (Y) satisfied to allow for the water to be evaporated before it collected and dropped off the middle of the coil. Just remember that this solution will only work in normal humidity situations where the air can re-absorb the excess water before it can drop off and may not always work 100% of the time.
    Good luck and Happy Motoring!

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  5. #5
    Join Date
    Dec 2010
    Location
    Down by the river
    Posts
    1,646
    Any chance the bottom 1/2 of the coil was dry, this would allow the water to not stick on that part surface.

  6. #6
    Join Date
    Feb 2012
    Location
    EVERYWHERE
    Posts
    228
    Try to clean the coil with triple D cleaner.

  7. #7
    Join Date
    May 2002
    Location
    evansville indiana
    Posts
    943
    I assume each units charge is correct.
    and the superheat for each is correct .
    And it is staged properly, meaning the coils first stage is actually connected to the first on condenser, the second stage is connected to the last on condenser .

    But you said it drips with both on .

    to much airflow maybe , Assuming its charged properly and running properly ,whats your td ? Is it normal ,high,?or low?


    I've seen new coils with a lot of manufacturing oil on them drip water.

    Clean it to strip any oil off it and see what happens.

    Ive even cleaned them first and then dissolved some dishwasher soap in water and sprayed the coil down with the solution and let them self rinse. dishwasher soap ,such as powdered cascade , has been known to help dripping coils .

  8. #8
    Join Date
    Jun 2009
    Location
    Pompano Bch, S Fla
    Posts
    57
    Didn't check subcool or td yet bc I was doing all the other incidental stuff but the pressures seemed normal enough until we get the building back to normal temp and can adjust properly. Circuits are correct and it's txv so I wasn't planning on checking superheat. As for the bottom half the specs I found on Rheem's site say the coils are interlaced so I don't think that's it. I considered the oil theory so it is good to hear some support of that. Will suggest the dish soap to boss. Last but not least, I thought it might be airflow but I was thinking not enough. Why would too much cause it to drip?
    Thank you all for your suggestions. I'll let you know what happens.

  9. #9
    Join Date
    Jul 2005
    Posts
    5,491
    Quote Originally Posted by Pete954 View Post
    Didn't check subcool or td yet bc I was doing all the other incidental stuff but the pressures seemed normal enough until we get the building back to normal temp and can adjust properly. Circuits are correct and it's txv so I wasn't planning on checking superheat. As for the bottom half the specs I found on Rheem's site say the coils are interlaced so I don't think that's it. I considered the oil theory so it is good to hear some support of that. Will suggest the dish soap to boss. Last but not least, I thought it might be airflow but I was thinking not enough. Why would too much cause it to drip?
    Thank you all for your suggestions. I'll let you know what happens.
    It isn't an airflow issue. Excess air flow could cause condensate to pull off, but it wouldn't cause it to drip off. Low air flow shouldn't cause dripping, because the coil shouldn't drip even when the blower cycles off. It's probably oil on the coil. You said it had a leak, so I'd probably start by leak testing the coil in the finned area.

  10. #10
    Join Date
    Jan 2011
    Location
    Boston, MA
    Posts
    459
    I'd start with checking airflow and washing/cleaning it too.

  11. #11
    Join Date
    Jan 2011
    Location
    Boston, MA
    Posts
    459
    Good catch medic, your right if it's dripping its not an airflow issue..I was thinking "flying" off for some reason.

  12. #12
    Join Date
    Jun 2009
    Location
    Pompano Bch, S Fla
    Posts
    57
    The leak was a tiny spot that someone missed while brazing in the sightglass. Nowhere near the evap. Definitely going to suggset cleaning the coil. Hope the boss listens. Thanks all.

  13. #13
    Join Date
    Jul 2005
    Posts
    5,491
    Quote Originally Posted by Pete954 View Post
    The leak was a tiny spot that someone missed while brazing in the sightglass. Nowhere near the evap. Definitely going to suggset cleaning the coil. Hope the boss listens. Thanks all.
    Then let me rephrase. I'd start be leak testing the coil. Literally, that's what I'd do if I were there.

    It doesn't really matter whether someone found a leak near the sight glass, there could be more than one leak in the system. If a leak in the coil is the source of the oil that is causing the condensate drip (if oil is the culprit), then cleaning the coil only to have the dripping start back up in two weeks will look to the customer like you're just guessing at the problem. And they'd be correct, because at this point you are only guessing. If OTOH, you find a leak in the coil first, then you can save yourself the trouble of cleaning it, and from the embarassment of cleaning it only to find that it didn't fix anything. HTH.

    If there is no leak in the coil, then you're only out a few minutes time.

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