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  1. #1
    Join Date
    Aug 2010
    Location
    UK
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    McQuay WHS 248.2 water flow



    Hello everyone

    I've got a couple of McQuay WHS 248.2 water-cooled chillers.

    On one of them there is a controller issue where the chiller will start even if there is no water flow. The differential switches are working properly and the controller can see the change of state of the input when the flow is made or removed.

    I think that the program in the Carel has become corrupted. Has anyone elese ever had this issue? Any suggestions?

    Any help greatly appreciated.



  2. #2
    Join Date
    Jun 2008
    Location
    Albania
    Age
    50
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    Re: McQuay WHS 248.2 water flow

    hello piewie !I have some experience with Carel controllers in air to water chillers made by Galletti Italy .
    The display has different screens in mcQuay but the controller is basically the same and in maintenance menu there is a screen where you can put manually the status of an imput or output , so if someone has changed it than the controller will not "see" the flow switch . The screens are programmable by the end user so for sure it will be different from galletti and I can' t help you further .

  3. #3
    Join Date
    Jun 2008
    Location
    Albania
    Age
    50
    Posts
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    Re: McQuay WHS 248.2 water flow

    I am working for 8 years with these controllers and i have had no problems with Carel never.

  4. #4
    Join Date
    Jun 2011
    Location
    Australia
    Age
    44
    Posts
    336
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    21

    Re: McQuay WHS 248.2 water flow

    Hi,

    The following is an extract from a document that I have

    When the unit starts, there has to be 20 sec of flow during the first 30 sec of pump operation. When the unit is running, the flow switch has to be open for 5 sec before the unit trips in flow alarm

    Perhaps it's a timer?

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