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New Carrier RTU's Tech Tip

Discussion in 'Commercial' started by SmallChange, Jan 22, 2018.

  1. SmallChange

    SmallChange This Space for Rent

    Messages:
    193
    RTU Tech Tip from John Wozniak

    Attention all Commercial Contractors and
    Service Technicians

    In order to meet the new DOE, (Department of Energy), efficiency ratings adopted January 1, 2018 in Ohio, all new Carrier rooftop units 6 tons and larger, manufactured after 1.1.2018, will have a 2-speed indoor fan motor.

    This is done at the factory with a VFD (Variable Frequency Drive) that is pre-programmed for two speed operation. The VFD sends power to the indoor fan motor in such a way that the motor will ALWAYS rotate in the proper direction regardless of phasing. This means that even if you switch two legs of incoming power the motor will still turn the correct direction.

    PROPER UNIT PHASING CAN NO LONGER BE VERIFIED BY CHECKING INDOOR FAN MOTOR ROTATION ONLY!

    COMPRESSOR ROTATION MUST BE VERIFIED WITH REFRIGERANT GAUGES!


    Please feel free to call or email me with any questions or concerns.
    Thank you for your time.


    John Wozniak
     
    BBeerme and newtech like this.
  2. Chuck

    Chuck SSP

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    I use my meter to verify phase rotation before starting units
     
    David DeBord likes this.
  3. frozensolid

    frozensolid Psychologist's Dream

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    I just grab all three wires and see which way I twist. :)
     
    David DeBord, BBeerme, R/HVAC and 6 others like this.
  4. knave

    knave Undeterred

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    All units use 1,2,3 rotation? What if the motor is hooked up for 1,3,2?
     
  5. Texas-Tech

    Texas-Tech Official Geezer*

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    duhh
    The vfd will always turn the motor fwd
     
  6. knave

    knave Undeterred

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    Compressor motor :chairshot:
     
  7. Texas-Tech

    Texas-Tech Official Geezer*

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    duhh
    Put down that chair, he was talking about the blower motor
     
    David DeBord, newtech and knave like this.
  8. heavyevans

    heavyevans FNG

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    The motor will spin the right direction only if the output of the VFD is wired correctly. :cheers:
     
  9. knave

    knave Undeterred

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    Whew ok sure thing.
     
  10. Chuck

    Chuck SSP

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    A common test to make sure that the unit is wired right before starting the compressor was to energize blower and see if it turns the right way. That bulletin he posted was saying that since the vfd will turn the blower the correct way it was no longer a valid test to be sure the unit was wired right before starting compressor.
    That's the factory's problem, they are the ones labeling their unit L1,L2,L3. Obviously I'm still listening to the pump when it starts.
     
  11. jamesyarbrough

    jamesyarbrough Amateur Gynecologist

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    Idk maybe I missed something. I always hook up gages and check rotation on all the motors. There's no telling if the guy at the factory wired it all the same or not. It never crossed my mind to only check one motor
     
  12. Zman

    Zman Hanging by a Thread

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    The "I know a Guy" State
    Speaking of Phase Rotation,if it was reversed,where is it preferable to switch 2 of the legs? At the disconnect,or after somewhere along the way? I vote for Disconnect Output.
     
  13. Catpower

    Catpower The Crowd Pleaser

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    I never check anything, I don't need to, I am the Chuck Norris of the HVAC/R world, the shit is scared to death of me so it runs right automatically out of fear:thumb::damnit::lachen::lachen::lachen:
     
    David DeBord likes this.
  14. LemonWizard

    LemonWizard Blinky Lights Wizard

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    They must not be running scrolls in them models. You'll know if a scroll is phased wrong long before your gauges read chit.

    It also occurs to me that they could fix this issue by putting a "vfd that always turns the correct direction" on the compressor. :dunno:
     
    David DeBord and Catpower like this.
  15. Ballvalve79

    Ballvalve79 It's only fire what could go wrong

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    All this from the company too cheap to put in a three pole contactor on the compressor. SOB always a hot leg of power wtf.
     
    Chuck likes this.
  16. flange

    flange Act like you care and do SOMETHING!!

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    none of you own phase rotation meters I guess
     
    ub2slo likes this.
  17. crackertech

    crackertech assholiness *

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    Most probably don’t know what they are lol
     
  18. knave

    knave Undeterred

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  19. Zman

    Zman Hanging by a Thread

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    The "I know a Guy" State
    if phases were reversed,and you hooked your meter backwards,would it show correct Rotation? :headscratch:...:D
     
  20. flange

    flange Act like you care and do SOMETHING!!

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    13,044
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    IMT--in my truck