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Testing a Taco 008-VVSF6 pump motor

Swizzle
Swizzle Member Posts: 3
in Radiant Heating

Hello, the variable voltage, variable speed circ pump on my HTP combi boiler was stuck and the motor case became too hot to touch when I turned on my hydronic heating this fall. I replaced the cartridge in the motor, put it back on the boiler and it ran and pulsed for 10 or 15 seconds, then stopped completely. Green LED still on and Orange LED blinking on the pump motor board. Took the pump off the boiler, plugged it in to run it uninstalled, and it blew the main fuse in the boiler (not the pump motor fuse, the main fuse). Replaced the fuse, boiler works fine, the motor power leads from the boiler board test at 120VAC and the motor control leads are at 9.8VDC, calling for full pump flow (it’s a 0-10VDC control). The motor winding resistances test as follows: Yellow to red 2.9 ohms, yellow to black 8.9 ohms, red to black is 6.6 ohms.  None are shorted to the motor case. Connected the motor power direct to 120VAC, and applied 9VDC to the control. The green power LED stays on, and the orange % Out LED blinks slowly at first, then after a few seconds blinks quickly, but no sound or movement from the motor at all. Does the winding resistance sound about right for this little motor? What does the flashing orange light mean? I don’t remember if it flashed or not when the pump was working, the LEDs were under a cover. Is there a combination in the dip switches that tell the motor to run regardless of control circuit input? Any suggestions appreciated on the best way to test this pump motor before dropping $1200 on a complete new pump. Would like to figure out if it is something on the board, or if it is the motor windings. Thanks, Greg

IMG_9618.jpeg

Comments

  • Swizzle
    Swizzle Member Posts: 3
    edited December 2024
    IMG_9614.jpeg

  • SteveSan
    SteveSan Member Posts: 279

    It appears that the motor/windings might be on the way out. The ohms should for any 008 pump Y-R 46-37, Y-B 96-117, and R-B 133-163.

    Our circ. pumps do run hot to the touch. Under normal operation should be between 140F-160F.

    Sequence of Operation: Whenever the 00-VV is powered up, the green power LED turns on and the pump operates based on an analog input signal. The percent output (% OUT) LED flashes at different rates based on the speed of the pump. As the % OUT LED flashes faster it indicates a fasterspeed of the pump. A fully on LED indicates the pump is at 100% capacity

    If you have any questions, please give Taco Technical Services a call during normal business hours Mon-Fri 8am-5pm EST 401-942-8000 and just ask for Technical Services.

    Dave H_2
  • hot_rod
    hot_rod Member Posts: 23,886

    I think the pump will run close to the fluid temperature running through it, maybe a bit higher?.

    It is a wet rotor type of circulator. So if it is running 180F for a DHW heat exchanger, it may be pretty warm to the touch. Most wet rotors are listed to 225°F, even versions with electronics attached. The temperature limit may even be on the label attached to the circulator.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Swizzle
    Swizzle Member Posts: 3
    edited December 2024

    Wow, this is great info guys. Thanks for the detail on the motor winding resistance, SteveSan. I wish I would have checked here on that before replacing the cartridge. With the winding resistance well below spec, and the rotor not turning, explains the high amperage blowing the fuse. I’ll look into sourcing a new pump/motor assembly. Thanks again for the detail. Greg

    SteveSan

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