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  1. #1
    Join Date
    Mar 2006
    Location
    Ventura, CA
    Posts
    17

    Pumpdown a Mcquay Rdt115CLY

    Getting started with a new commercial group, they gave me a ticket to change cores on a Mcquay 115 ton unit that is frosting at the drier can. I see the unit pumps itself down at shutoff. Do I have to power down entire unit after shutdown or can I pump it down and pull the relays out of the micro tek board to keep the circuit down and turn the other bank of compressors and the VFD's back on? I could use any constructive help.
    It's not just a job, it's an adventure...

  2. #2
    Join Date
    Jun 2005
    Location
    The Gray Northwest
    Posts
    661
    You're trying to keep the other circuits running while you replace the filters, correct? I'm assuming that they are on thier own refer circuits and not have a common evap or cond coil? On my McQuay units, I have to reclaim the charge to change the drier cores becasue you're pumping down to the liquid side, unless you have isolation valves on the drier (doubtful).

  3. #3
    Join Date
    Mar 2006
    Location
    Ventura, CA
    Posts
    17

    Figured it out

    This Mcquay unit is Dual circuited with two compressors tied together on each circuit. There is an isolation valve before the drier can so I shut that, jumpered the low pressure cutout and ran the system in pump down. When I got down to 10 PSI I shut the control circuit off and closed all service valves on the compressors. I still had to reclaim a couple of pounds, but it all worked great. Love those McQuay's. Coincedentally when I opened the filter can I found my suction vales in there with the cores. So it looks like I'll be changing valve plates.
    It's not just a job, it's an adventure...

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