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  1. #1
    Join Date
    Jan 2005
    Location
    Phoenix, AZ
    Posts
    50

    Closed loop was foamy and eating nitrites

    I've been assigned responsibility for the closed loop treatment in a number of city of Phoenix facilities, and I normally use NuCalgon's TyIon B-20 nitrite/borax loop treatment. I like the fact that it has a (pink) dye added so you can tell the difference between condensation and a leak.

    A few weeks ago I checked the loop at a police precinct that has a dozen water-source heat pumps, mostly three or four tons each. My supervisor requests that I keep the nitrite around 2000 ppm in loops that are assisted by a boiler.

    I found the loop water foamy last month, and it smelled weird.
    TDS was reasonable, 4700 (city water at 1100). With a TDS
    that high, I assumed that the nitrite level would be good. It wasn't; it was at 360 ppm.

    I'm guessing that the foam was caused by a pinhole leak in one of the (R-22) heat pumps. It's not cold enough here that they would notice a heat pump not working in the winter, so we haven't gotten any service calls yet.

    I drained the loop, used some NuCalgon system cleaner, drained and flushed it again.
    TDS is pegged (over 5K) and nitrite is back to a comfortable 1960. But I think I'm seeing tiny bubbles in it again.


    My supervisor doesn’t think there’s enough refrigerant in one of the heat pumps to cause this much foam and bubbles. The largest one holds 6˝ lbs. I've never seen foam or bubbles in a loop before, and wonder if anyone here has any other ideas or maybe experienced this before. My guess is that one of the units has a tiny leak in the coil, and that some kind of weird chemical reaction happened with the nitrite.


    Thanks in advance.

    Vicki in Phoenix

  2. #2
    Join Date
    Jan 2005
    Location
    Phoenix, AZ
    Posts
    50
    Okay, I went back this afternoon. TDS is down to 4400, nitrite is down to 1000. Still a little foam in the loop. I'm going to put a water meter on it next week to see if we have a leak, but that doesn't explain the weird smell and the tiny bubbles.

    Vicki in Phoenix


  3. #3
    Join Date
    Apr 2007
    Location
    Central PA
    Posts
    51
    We have a similar problem with one of our buildings. Our water guy thinks it is bacteria , we have treated with biocides but still have problems.

  4. #4
    Join Date
    Jan 2005
    Location
    Phoenix, AZ
    Posts
    50
    I don't think so because I've seen that happen at a waste water treatment plant closed loop and it's gradual with no foaming, not losing half the nitrite in three days like I'm seeing.

  5. #5
    Join Date
    Apr 2012
    Location
    arizona
    Posts
    20
    Sounds more like you have a leak.
    As previously stated denitrifing bacteria would be more like months not days... also your "TDs" would remain constant if that was the problem not dropping consistent with the no2 "nitrite".

  6. #6
    Join Date
    Sep 2006
    Location
    Ohio
    Posts
    456
    Sounds like you may have more than one problem. Foam is often caused by oil in the water loop. Refrigerant wouldn't cause it, but the refrigerant oil would. The odd odor could be bacteria or fungi and this could also cause the nitrite to drop. A water leak would also cause the nitrite to drop and if the makeup water TDS is 1100 ppm, it would make the system TDS to go up. A water meter is a good idea to see if you have a leak and you just may have a refrigerant leak in one of the Heat Pumps.

  7. #7
    Join Date
    Apr 2012
    Location
    arizona
    Posts
    20
    If you have a filter housing on the system the filter will have oil in the housing and on the filter surface if there is a refrigerant in the loop... I had it happen recently at an account that I service in mesa.

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