busted belt gone wrong
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  1. #1
    Join Date
    Nov 2005
    Location
    Massachusetts
    Posts
    127

    busted belt gone wrong

    also tore up some control wiring in its path
    Attached Images Attached Images   
    To err is human, to really screw things up takes a service manager

  2. #2
    Join Date
    Oct 2005
    Location
    Kermit, TX
    Posts
    718
    I've got a Lennox that did that. Took out the wiring to the condenser fan motors and wrapped them and the belt around the motor shaft. When it shorted it took out the fan relay, 1st stage compressor contactor and the control board. 460v on the control side isnt too good.
    Zach

  3. #3
    Join Date
    Jun 2000
    Location
    B.C. Canada
    Posts
    147
    I had a Lennox also do that, L-series unit flattened the discharge to the condensor.

  4. #4
    Join Date
    Nov 2005
    Location
    Massachusetts
    Posts
    127
    this was on a 50 ton carrier
    To err is human, to really screw things up takes a service manager

  5. #5

    Cool

    allso lookz lick the wrong size belt on that unit needs a bigger belt

  6. #6
    Join Date
    Nov 2005
    Location
    Massachusetts
    Posts
    127
    no that used yo be correct size... worn then snapped
    To err is human, to really screw things up takes a service manager

  7. #7
    Join Date
    Jul 2008
    Location
    Washington, DC
    Posts
    1,582
    i've seen that happen on a new rooftop unit where the balancing guy had opened the motor pulley to the point the belt wedged in the pulley and then snapped. took out a lot of control wires. It looks to me like the motor pulley is opened up too far in this unit also, you might consider putting a smaller pulley on it

  8. #8
    Join Date
    Nov 2005
    Location
    Massachusetts
    Posts
    127
    good observation, included in repair was a new sheave... yet adjusted much further closed
    To err is human, to really screw things up takes a service manager

  9. #9
    Join Date
    Jul 2008
    Location
    Washington, DC
    Posts
    1,582
    Quote Originally Posted by scottiedawg View Post
    good observation, included in repair was a new sheave... yet adjusted much further closed
    If you close it up you are going to speed your fan up, you will get more air flow and a higher amp draw. I would put the new belt on it with the old pulley and amp the motor and then put a smaller pulley on it and adjust it until your amp draw is the same as it was with the original.

  10. #10
    Join Date
    Nov 2005
    Location
    Massachusetts
    Posts
    127
    air/amp draw was low in the first place
    To err is human, to really screw things up takes a service manager

  11. #11
    Join Date
    Mar 2008
    Location
    NY NY
    Posts
    181
    The adjustable sheave on this motor appears to exhibit little or no wear.

    I find it best when working with adjustable fan drives to use a reflective tachometer, when speed comparison or adjustments become necessary.

    The power of the motor changes the cube of the speed. A small variation in fan speed is a much larger change in power.

    Just a hint from a regular member.

  12. #12
    Join Date
    Jul 2008
    Location
    Washington, DC
    Posts
    1,582
    Quote Originally Posted by kdocsr05 View Post
    The adjustable sheave on this motor appears to exhibit little or no wear.

    I find it best when working with adjustable fan drives to use a reflective tachometer, when speed comparison or adjustments become necessary.

    The power of the motor changes the cube of the speed. A small variation in fan speed is a much larger change in power.

    Just a hint from a regular member.
    How much can you change the power without changing the amperage?

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