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  1. #1
    Join Date
    Mar 2013
    Location
    swan valley idaho
    Posts
    727

    copeland compressor curve with fan cycle

    how do you use curve when condenser uses a fan cycle, and head pressure varies by 50 psi? do you just use average condensing temp, or does it not really work with fan cycle?

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,659
    Quote Originally Posted by kklobas View Post
    how do you use curve when condenser uses a fan cycle, and head pressure varies by 50 psi? do you just use average condensing temp, or does it not really work with fan cycle?

    A compressor performance curve is really a "snapshot" in time.

    It works best if you can get things to a steady state, or at least take your readings from a single set of conditions.

    Let's try to put it into practice because I'm not sure I'm explaining it well.

    We'll install our gauges and other instruments.

    If we take our pressure readings just before the condenser fan cycles on and take our electrical readings just before the fan cycles off, our "snapshot" won't be very accurate, will it?

    So, we try to take all of our readings at the same conditions or as close to the same conditions as possible.


    Make sense?

  3. #3
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,595
    Maybe it'd be easier to disable the fan cycle control, block off the condenser and let everything stabilize then take you "snapshot"?

  4. #4
    Join Date
    Mar 2005
    Location
    5,000 ft
    Posts
    2,192
    Quote Originally Posted by ryan1088 View Post
    Maybe it'd be easier to disable the fan cycle control, block off the condenser and let everything stabilize then take you "snapshot"?
    ^^^ Ditto

    I usually use a pieceof cardboard and block off to maintain condensing saturation of 95 to 115*F

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