Mcquay Unit Ventilator Problem/ Service Tool
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  1. #1
    Join Date
    Apr 2006
    Location
    Columbus, Ohio
    Posts
    768

    Mcquay Unit Ventilator Problem/ Service Tool

    We have a job that has multiple Mcquay Unit Ventilators. Apparently they keep freezing and busting there hot water coils. This has happened on over 25 units over the past 2 years. A Mcquay factory service technician has hooked up to the board with Service Tool multiple times to reprogram/download new programs into the controller. I am being told that the problem still continues. I guess my company is going to purchase Mcquay Service Tool and send me out to look at this problem. These unit ventilators have outdoor air capability.

    I haven't used Service Tool software before. So I am wondering what all can I really do with the software when it comes to these boards? I believe this unit probably has a Microtech II board in it.

    Obviously I will check all of the basic sequence of operation checks and look for any possible mechanical issues, but I was wondering if you guys have seen this problem with the Mcquay Unit Ventilators?

    If I can do programming changes through Service Tool. What kind of things should I look for to be in this program to prevent this problem? I am assuming if the fan fails, open the hot water valve. If I have a freeze condition, open the hot water valve turn off the fan. Mechanically I will make sure the hot water valves are normally open.


    Thanks for any help on this.
    J. King

  2. #2
    Join Date
    Dec 2001
    Posts
    213
    When I worked for McQuay back about 20 Years ago we used "Monitor Software" to calibrate the outdoor air damper counts. this was done during the start up phase of EVERY unit. The process needed to be performed to calibrate the stroke of the damper......

    Our Monitor Software was a DOS based batchfile that was an assembly of files specific to the equipment....

    It was somewhat common to see a frozen coil when the installing contractor would start up the equipment in extreme conditions with out having a proper start up done on this equipment.

  3. #3
    Join Date
    Jan 2003
    Location
    USA
    Posts
    1,641
    I would be asking why the freezestat didn't save the coils.

    Are the actuators spring return?
    Propagating the formula. http://www.noagendashow.com/

  4. #4
    Join Date
    Apr 2006
    Location
    Columbus, Ohio
    Posts
    768
    Quote Originally Posted by orion242 View Post
    I would be asking why the freezestat didn't save the coils.

    Are the actuators spring return?
    Ya the freeze stat was the first thing I asked about. It is hard for me to believe it has anything to do with the controls, but I could be wrong. I am not sure about the actuators being spring return, but I will find out. I will be going to the job next week or so.

    Thanks!
    J. King

  5. #5
    Join Date
    Apr 2006
    Location
    Columbus, Ohio
    Posts
    768
    Quote Originally Posted by acddc View Post
    When I worked for McQuay back about 20 Years ago we used "Monitor Software" to calibrate the outdoor air damper counts. this was done during the start up phase of EVERY unit. The process needed to be performed to calibrate the stroke of the damper......

    Our Monitor Software was a DOS based batchfile that was an assembly of files specific to the equipment....

    It was somewhat common to see a frozen coil when the installing contractor would start up the equipment in extreme conditions with out having a proper start up done on this equipment.
    Thanks for the reply. I will take this in consideration.
    J. King

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