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  1. #1
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    Run Capacitor Wiring

    Just curious if one way is better than the other.....

    some schematics show the C of a dual run cap coming from the switched side of the contactor and some show it wired to the shunt side.

    is there any advantage to keeping the cap hot all the time?

  2. #2
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    In either scenario the capacitor will be energized in reference to ground just not to the floating conductors.

    If you have a single pole contactor you have juice whether it be through the motor or right off the line.

  3. #3
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    To make my post more accurate, their is no floating conductors. Just energized ones.

  4. #4
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    Confused

    Quote Originally Posted by Core_d View Post
    To make my post more accurate, their is no floating conductors. Just energized ones.
    Thanks for the reply. I understood "floating"....now if I had been in downtown New Orleans during Katrina, I might have been a little confused:

  5. #5
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    Quote Originally Posted by johnredd View Post
    is there any advantage to keeping the cap hot all the time?
    When wired to the shunt, sometimes it is used in/as a crankcase heater circuit. They are using the run winding as the heater.

  6. #6
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    Quote Originally Posted by BBeerme View Post
    ... They are using the run winding as the heater.
    I think you meant start winding like those old Trane did in the early 80's.

  7. #7
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    Quote Originally Posted by just_opinion View Post
    I think you meant start winding like those old Trane did in the early 80's.
    Yeah, I guess, haven't seen one in so long. Regardless, it's on one of them thar spools of wire inside that big black thing.

    The tip off, of course, is the resister on the run cap. If memory serves.

  8. #8
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    Quote Originally Posted by BBeerme View Post
    Yeah, I guess, haven't seen one in so long. Regardless, it's on one of them thar spools of wire inside that big black thing.

    The tip off, of course, is the resister on the run cap. If memory serves.
    I thought the resistor was to discharge the cap on off cycle if the cap wasn't able to discharge through a motor winding?

    Sent from my HTC One S using Tapatalk 2

  9. #9
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    Quote Originally Posted by timtanguay View Post
    I thought the resistor was to discharge the cap on off cycle if the cap wasn't able to discharge through a motor winding?
    You're thinking of the resistor on the start cap that is used for starting the compressor. There is also a way to use a winding inside the compressor as a crankcase heater. For that they use a run cap with a resistor on it. Think I've got a wiring diagram of it somewhere.

    Well, it only took me about 10 seconds to find this on the Internet. Sort of a piss poor drawing, really, but it should give you the insight.

    http://www.achrnews.com/NEWS/2003/31...ages/86335.gif

    Probably the single biggest take away point here is that if they are using a compressor winding as the crankcase heater, and you change out a shunted two pole contactor with a regular two pole contactor, you just disabled the crankcase heater.

  10. #10
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    Quote Originally Posted by BBeerme View Post

    Probably the single biggest take away point here is that if they are using a compressor winding as the crankcase heater, and you change out a shunted two pole contactor with a regular two pole contactor, you just disabled the crankcase heater.
    Not if you wire it correctly.
    "...and pray it works, pray to God it works."

    ---Nick's Handyman

    https://www.youtube.com/watch?v=NGllepZY2HE

  11. #11
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    Quote Originally Posted by hurtinhvac View Post
    Not if you wire it correctly.
    Try finding a rookie that would know the difference. Heck, there are 'journeymen' out there that don't even know what they're looking at.

    In my beginning years, I probably bypassed a couple of those crankcase heating circuits.

  12. #12
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    Quote Originally Posted by BBeerme View Post
    You're thinking of the resistor on the start cap that is used for starting the compressor. There is also a way to use a winding inside the compressor as a crankcase heater. For that they use a run cap with a resistor on it. Think I've got a wiring diagram of it somewhere.

    Well, it only took me about 10 seconds to find this on the Internet. Sort of a piss poor drawing, really, but it should give you the insight.

    http://www.achrnews.com/NEWS/2003/31...ages/86335.gif

    Probably the single biggest take away point here is that if they are using a compressor winding as the crankcase heater, and you change out a shunted two pole contactor with a regular two pole contactor, you just disabled the crankcase heater.

    That bleed resistor is the same thing that you find or install on a start cap, no difference

    Hope this helps
    Isn't sanity just a one-trick pony anyway? I mean, all you get is that one trick, rational thinking, but when you're good and crazy, well, the sky's the limit!

  13. #13
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    Jun 2011
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    Quote Originally Posted by skpkey9 View Post
    That bleed resistor is the same thing that you find or install on a start cap, no difference

    Hope this helps
    Wow thats some golden advice, I will keep an eye out for that from now on.

    Sent from my HTC One S using Tapatalk 2

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