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Wiring old damper motors

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TFK
TFK Member Posts: 2
I hope the Wall is appropriate for this topic. 

Years ago, I replaced my furnace and added A/C. The system is two-zone forced air, and at the time I couldn’t afford the added expense of having a control panel installed, so I had them hook up only one thermostat and leave the dampers open, with the hope of eventually adding a control panel. Having only one zone has sufficed, but now I would like to reactivate the system. 

Unfortunately, I forgot to grab the panel with the wiring diagram from the old furnace. When I asked a HVAC pro about the motors (images attached), the answer was simply, “they’re obsolete.” 

Can anyone explain how the wiring works? Or point me to a good resource for figuring it out? (Or suggest good replacement motors?)


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  • HVACNUT
    HVACNUT Member Posts: 5,888
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    I would update everything. Honeywell or EWC panel and dampers. No summer/winter switch. No master/slave thermostats. 
    Is the blower motor ECM, or is there a bypass relief?
    TFK
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,835
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    I haven't seen one of those in years.

    24 volt power from your transformer (2) wires 1 goes on T the other wire goes on R on the motor. Then the thermostat should be a 3 wire single pole double throw they used to use Honeywell T26 thermostat. You could also use a old mercury Honeywell T86 or T87. Then you need 3 wires from the motor to the thermostat.

    On the motor you connect the 3 thermostat wires R on motor goes to R on the thermostat. W on thermostat to W on motor and B on the motor to Y on the thermostat. The thermostat if one of the above will have a sub base. The motor is drive open and drive shut. If it works backwards you swap the W & B
    wires on the motor
    TFK
  • ch4man
    ch4man Member Posts: 296
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    blue for BTU, Y closes the damper in heating mode

    I think
  • ch4man
    ch4man Member Posts: 296
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    EWC is the system id recommend for replacement as you have single dampers rather than opposed damper assemblies
    TFK
  • TFK
    TFK Member Posts: 2
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    Thanks for the info! The blower is ECM and keeping up with the below zero weather in MN!