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perennial proportional cooling water temp control question

Looking for a proportional temperature controller for a cold water chiller that feeds fan coil units for air conditioning.

This is twin 7 and 1/2 ton compressors in a single Trane chiller unit, about 15 years old. The supplied controls use an manually adjustable differential to call the second stage. I put in a spdt switch to change the lead lag assignment each year, but there is no 'cool weather shut down'. I'm was going to engineer that with a simple air conditioning control thermostat independently, but it occurs to me that while proportional water temperature control might not be as relevant or money saving in this context -- given that the operating range of water temperatures sawy 35 to 65 F is much more constrained than on the heating side, it still might squeeze a few more energy pennies out of the system if I were to replace the existing controls with some analog of a PC 702 designed for two stage air conditioning rather than two stage heating.

Anyone aware of any control company working in this area. Last time I checked I don't believe there was such a control.

Thanks

Brian

Comments

  • Empire_2
    Empire_2 Member Posts: 2,343
    Thoughts

    Have you checked out Tekmar Controls? I have used them on the Trane 40 ton chiller, but for the life of me I cannot remember the mod # of the Tekmar that I used. Your Lead/Lag can be controlled in a variety of ways and I think they even offer this option, but I did not use it. Also I don't know how many fans you have , but watch that you are energising them after lead lag changes. That is depending how it's wired.

    My .02

    Mike T.
  • mtfallsmikey
    mtfallsmikey Member Posts: 765
    How 'bout

    Trane itself or Johnson controls? Do you run DDC? If you are in the Metro D.C. area, let me know.
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