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  1. #1
    Join Date
    Aug 2006
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    WSC087 MicrotechII centrifugal

    I'm a chiller mechanic in Toronto.
    I took over a building with a wsc running microtechII, with an oits.
    Someone has changed the rla cap to 70% and with the 98f temps we have been having the machine is overloaded and tripping high motor temp.
    At first I thought it was a guardister problem. So I rewired the thermister circuit and changed the board because I hadn't actually seen it trip. I have since then and the board isn't the problem. It's tripping 230' right where it's supposed to. I've been speaking to Mcquay factory guys and they all agree it shouldn't be at 70% but no one will give a t level pass out and Mcquay is too busy to send a tech out to do it for me.
    The machine will run at 70Max for 12 hrs at a time. Cannot maintain load. Water temp still at 54 until it over heats.
    If someone wants to give me a call I can give more info if you want. I'm very experienced in centrifugals but I can't get past the password.
    Anyone with info that can help out can contact me at 416 571-2964 or email at
    Thank You

  2. #2
    Join Date
    Apr 2010
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    Your chiller should not be going off on motor temp if it is running 70%.
    My guess would be,low on refrigerant,plugged up motor cooling filter,check valve stuck,service valve not opened all the way ,plugged up orfice.What is your motor return line temp,(measured with a thermometer)what is your discharge superheat,(liquid injection off!!).what is your subcooling.Is your motor cooling sight glass clear?Is your current set right.Is it a solid state starter or a wye delta.

  3. #3
    Join Date
    Dec 2005
    Rockhill South Carolina
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    Check your email

  4. #4
    Join Date
    May 2001
    Western Wa
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    I'd be interested in the outcome of this one.
    God Bless our Veterans

    God Bless the USA

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