Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit

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.




  • Empire_2
    Empire_2 Member Posts: 2,343

    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.
This discussion has been closed.


It looks like you're new here. If you want to get involved, click one of these buttons!