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  1. #1
    Join Date
    Feb 2008
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    Second City, USA
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    Tower Water/Winter Ops

    Having troubles holding anywhere near a steady entering tower water temp. and it's driving the connected 19XR chillers crazy. If I'm correct, the root cause at this point in time is a tower fan freq drive that was never set up properly. Looking for real world input as to the tolerable temp range with a 78F setpoint. Chillers run with a min load of about 70% FLA.

  2. #2
    Join Date
    Jan 2008
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    windy city
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    How low is temp dropping now? You know XR"s more better than me.
    \m/
    original member of the racoon brotherhood

  3. #3
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    Feb 2008
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    Have different issues with the extremes. In my mind the swing is far too wide. Looking at ems history swings are worst, as Billy Joel might say, IN THE MIDDLE OF THE NIGHT! Early this am swing was about 6 degrees in less than 30 minutes.

  4. #4
    Join Date
    Feb 2007
    Location
    Baltimore MD ( Balimer, Murilyn)
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    Are they 19XR's or XRV's? I had a problem with swinging temps on a job with the XRV's. Had customer lower the tower setpoint to 65 degrees. The XRVs are running about 45% motor current.

    The problem with the setpoint was controlled by Metasys(or as the local tech calls it Meta-mess). Johnson basically writes a software routine for tower control and downloads it into all there jobs whether it fits or not. The local techs have to tweak it to get it to work on a case by case basis.

    Course all this doesn't matter if you have 19 XR's. 65 degrees would probably be too low. Be that as it may, I don't think a 6 degree deviation in 30 minutes is too bad. We were looking at 15 degrees in about 15 minutes.

  5. #5
    Join Date
    Sep 2007
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    A mind is like a parachute. It doesn't work if it is not open.

    The best part of going to work is coming back home at the end of the day.

    Hard work spotlights the character of people: some turn up their sleeves, some turn up their noses, and some don't turn up at all.

  6. #6
    Join Date
    Feb 2008
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    Aha, just so happens this job has JCI controls. Looking at the available history I'm thinking 6 degrees is a best case scenario whenever weather conditions require 1 of the 4 tower fans. Seemed to hold about a 6 fegree swing with the tower fan speed range from zero to about 50% over the course of the day. Fortunately the chillers are XRs and not XRVs. They are however frame 5s with that movable diffuser and this winter all that have run have stored high lift alerts in their alarm histories.

  7. #7
    Join Date
    Dec 2010
    Location
    georgia
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    72 is about as low as you can deal with without head pressure control.

  8. #8
    Join Date
    Jan 2008
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    that the facility with the chillers on the 2nd floor, over the boilers?
    \m/
    original member of the racoon brotherhood

  9. #9
    Join Date
    Feb 2008
    Location
    Second City, USA
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    Heavymetaldad - You're probably thinking of the irght one, but you've got the equipment layout backwards. Boilers above chillers.

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