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New Blower Wheel Wobble: How Much Is Acceptable?

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PGB1
PGB1 Member Posts: 94
edited February 24 in A-C, Heat Pumps & Refrigeration

Hi All!

I have no experience with small, direct drive blowers, so I hope you don't mind my asking you guys who work with residential furnaces and air handlers.

We have a mini-duct air handler for air conditioning, humidifying and air cleaning. The blower motor's bearings went bad. With a new motor, the original wheel wobbled terribly. Measuring showed the hub was tilted on the dish.

I bought a new motor and a new blower wheel (10-5/8 x 4-1/4 x 1/2 bore). The new wheel wobbles and I am wondering how much is acceptable for new equipment.

The shaft of the motor is true, straight, has no end play and is square to the housing. Testing the wheel both on my machine lathe with a known true test bar and installed in the blower housing shows ca. 1/16" wobble. (Lathe test = 900 RPM. Installed test is spun by hand.)

The 1/16" was the distance from the edge of the wheel to a fixed spot as the wheel rotated.

I tried to attach two short videos (avi files) to explain what my words may fail to explain, but could not figure out how to get them to attach.

Is this amount of wobble acceptable, or should I expect perfection?

Thanks for sharing your expertise. I appreciate it.Paul

Comments

  • pecmsg
    pecmsg Member Posts: 7,024
    edited February 24

    Any vibrations are unacceptable.

    Early bearing / motor failure.

    PGB1
  • mattmia2
    mattmia2 Member Posts: 16,460
    edited February 24

    if it was balanced like that, 1/16" out of true is probably ok. does it vibrate or do you just see the wheel wobbling a little?

    PGB1
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,084

    Most have a little wobble. I don't think 1/16 will be an issue. Quality control. If it doesn't vibrate it should be ok.

    PGB1
  • PGB1
    PGB1 Member Posts: 94

    Thank you all for advice.

    Mattmia2 asked if it vibrates. All I've done so far is free-air bench testing and there is vibration.

    Perhaps I should install it and put the unit covers back on to find it if still vibrates when static pressure exists. The system is mini-duct, so the pressure is high and the RPM is 1,620.

    Does that installed test sound worthwhile?

    Thanks Again,

    Paul

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