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  1. #1
    Join Date
    Dec 2008
    Location
    Seattle WA
    Posts
    100

    JCI AS VAV-141 averaging temp sensors

    I need to average two space sensors on an older AS VAV-141 VAV Controller. Yes, I know it won't make anyone happy... but I have to do it. I have seen it done once before, but can't remember all the details.
    I remember that we leave the original temp sensor plugged into the RJ-45 jack, put a jumper between AI-1 and AI-2, and add a sensor to AI-6.
    We then read the temp from AI-2 and AI-6, average them, and write the value back to AI-1.

    This works because AI-1 is electrically connected to the motherboard to the T-stat jack, and with the jumper, now AI-2 is also. If configured properly, AI-1 and AI-2 will always read the same (based on the temp sensor) The result of using this method is that if the VAV is not communicating to the Global, the VAV will continue to operate using the T-stat that's on AI-1.

    What I can't remember is how AI-1 and AI-2 are to be configured?
    I seem to remember that one is to be setup as voltage, one as resistor temp sensor... ?
    And the dip switch settings on the card??

    Help?

  2. #2
    Join Date
    Feb 2009
    Location
    Northeast
    Posts
    320
    I think you got it. Set Ai 1 for the standard RTD setting and set AI2 for voltage and the 2V range. HVACPro Config is both for The RTD sensor type you are using. (Ni?). I do not have the controller with the DIP switches in front of me right now, but I think the switch positions are labeled on the metal cover.

  3. #3
    Join Date
    Dec 2008
    Location
    Seattle WA
    Posts
    100
    Billcontrols, I applied this on Saturday. Worked perfectly. Thank you!

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