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Noisy blower wheel on residential Forced Air furnace

George76George76 Posts: 18Member
If anybody feels like taking a look at this video to verify what I'm seeing, please feel free:

A tech replaced the blower motor and cleaned the fan blades a month ago, so ruling out motor or dirty blower wheel. Blower wheel seems balanced(stops spinning nicely without turning counterclockwise). But...

Well, please take a look, and let me know if you see what I see:

Comments

  • George76George76 Posts: 18Member
    Just to clarify, the tech replaced the motor because it died. This is a more recent problem of a noisy blower wheel, which was either already present or was possibly caused by bad motor.
  • SuperTechSuperTech Posts: 938Member
    I don't know, all I can hear is the TV in the background. Can't determine anything from that video.
  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,914Member
    If it is noisy with the new motor he likely damaged the blower wheel getting it off the old motor
  • SuperTechSuperTech Posts: 938Member
    > @EBEBRATT-Ed said:
    > If it is noisy with the new motor he likely damaged the blower wheel getting it off the old motor

    Or perhaps he over tightened the belly band on the motor? Maybe knocked one of the balancing weights off the wheel and it's out of balance? Can't determine anything from the video.
  • ratioratio Posts: 2,052Member
    An out of balance wheel could have caused the original motor to fail. If I were to replace the motor, I'd likely replace the wheel as well. It'd be cheaper to do it at the same time, as opposed to a second site visit.
  • HVACNUTHVACNUT Posts: 2,321Member
    Yeah, c'mon man. You want us to hear a noise and all I hear is the news.
    It doesn't look out of balance.
    Are you holding the blower assembly in your lap while taping? It should be in the equipment if you want to post a real example.
    Cant tell if an ECM, variable speed or PSC. In any case, solving a blower motor issue would require running with the doors on and checking amps.
    Reversible Rescue motor? Is it the correct rotation?
  • Intplm.Intplm. Posts: 777Member
    Sounds good to me. Can't hear what you are describing.
  • mikeg2015mikeg2015 Posts: 843Member
    Check rotation. Also, cleaning a blower wheel works sometimes, but often you can’t get it 100% clean and what you don’t remove ends up throwing it out of balance. Might need to replace the wheel too.

    Honestly, its not that hard to pull a blower and change the wheel.
  • George76George76 Posts: 18Member
    Sorry about the confusion.

    Just to clarify again---forgot to mention, this is being spun by hand and was looking for somebody to acknowledge that wheel looks out of balance/alignment. It rotates every couple seconds---if you pay attention to the gap between housing and wheel, you can see the gap change a bit on every rotation..

    I bought some evaporator coil cleaner to alleviate any blockage/restriction of air flow, but have to figure out how to disconnect piping/obstructions. It's a 90% efficient furnace with pvc piping.

    Compared it to unit upstairs and definitely is definitely louder.

    I ordered a new blower wheel, hopefully replacing it will fix problem.
  • JUGHNEJUGHNE Posts: 5,779Member
    Before you cut anything how about showing us what is in the way?
  • George76George76 Posts: 18Member
    I'll do that next time I'm over there
  • SuperTechSuperTech Posts: 938Member
    You should have applied line voltage to the motor with it removed from the unit. At the motors full speed you should easily be able to determine if the wheel is causing the noise, whatever it sounds like.

    Noise from a wheel out of balance is completely different from noise due to a restriction in air flow from a plugged coil.
    Static pressure readings will show you if the coil is plugged without cutting anything.
  • DZoroDZoro Posts: 771Member
    agree with all the above and add that a plugged secondary heat exchanger can also make the blower/wheel sound like the culprit. Check A/C coil also.
  • George76George76 Posts: 18Member
    SuperTech----Thanks for the tips----I'll try running the motor removed since I don't know how to perform a static pressure reading.

    DZoro---any idea how to inspect for plugged secondary heat exchanger?
  • George76George76 Posts: 18Member
    My only critique of the Plugged Coil theory is it doesn't seem to be affecting heat output.

    If you look at my original video post, I swear I detected the slightest bit of misalignment when I hand-turned the blower wheel...
  • JUGHNEJUGHNE Posts: 5,779Member
    Most motors for furnaces have end play in the shaft.
    If the wheel is too close it could scrap the housing when energized.
    The wheel needs to be centered on that play.
    I pull the shaft out and observe the clearance on the spin and then push the shaft in and do likewise. Find the happy medium.

    Did he change the run capacitor?
  • George76George76 Posts: 18Member
    Thanks, I will make sure to check the play on the motor shaft.

    I don't think he changed the capacitor---it was a quick job.
  • DZoroDZoro Posts: 771Member
    While you have the blower out of the furnace. Crawl inside with a flashlight, look up and you should see clean 1/8" spaced fins, no dirt, ect…
    Keep a good quality clean filter and you should have no issues with dirt.
    D
  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,914Member
    If the motor got changed and it's not an OEM you may need a different capacitor....need to check
  • HVACNUTHVACNUT Posts: 2,321Member
    edited March 30
    Swap it out to an ECM. You'll hardly know its on.
  • George76George76 Posts: 18Member
    HVACNUT--- What's an ECM?

    EDEBRATT-Ed--------he asked for model of furnace before getting new motor. Would having incorrect capacitor cause noise? It doesn't sound like motor noise, it sounds like vibrations..

  • HotanCoolHotanCool Posts: 49Member
    It's probably scrapping at high speed,like when energized! And the only way to completely clean a wheel is outside with water,or in a slop sink. But at that point,less labor to just replace. And it sounded fairly quiet to me as is.
  • rick in Alaskarick in Alaska Posts: 869Member
    I have had two now in the past month making horrible fan noises, which is the first time I have had this happen at all.
    What I found is the fan blades are coming loose from the center mounting plate, and are rattling like crazy. The first one was hard to detect, but you could see chafe marks where the blades were pressed on to the plate. The other one had two plates that flared out and "pinched" the blades on. We were in the process of changing out the first ones furnace, and it wasn't too bad so we left it alone. The other one was a Russian ladies house and was so noisy she and her kids did not sleep all night because they thought it was going to blow up. I was able to recrimp the blades for a temporary fix until her husband got home from fishing and could replace it himself.
    Rick
  • George76George76 Posts: 18Member
    This is not a huge noise, just a little annoying. No contact with housing or loose blades. Blower wheel was balanced just fine, some dirt not horrible.

    I took it apart, replaced with new blower wheel, wheel was still not turning true.

    Took a closer look at motor shaft to try to detect any misalignment, couldn't really tell.

    Looked inside the body of motor, and the disc that apparently is connected to shaft definitely seemed to have warpage that matched the wheel's slightly out of whack movements.

    Also theres a dent on the motor body.

    Turns out the guy who replaced it said last motor was barely holding onto the housing---brackets had unscrewed and were bent. He straightened them best as he could, he told me.

    So, he blamed the bent brackets for causing bad alignment in the new motor.

    The thing is, my tenant complained from day one of its installation of noisy furnace. I dont see how some bad brackets could ruin motor that fast.

    The dent is suspicious as well. I'm thinking it got dropped possibly.

    I'm gonna buy a new housing and try to get a new motor from the hvac guy for free since hes a friend.
  • Intplm.Intplm. Posts: 777Member
    Can you get the housing dent free from the path of the fan blades.Might be all you need.. That fan blade seems fine otherwise. Either way, best of luck with your tenant.
  • Big Ed_4Big Ed_4 Posts: 1,127Member
    It's always good practice to change the fan wheel or blade when changing the motor... Then your done
    I have enough experience to know , that I dont know it all
  • ChrisJChrisJ Posts: 9,896Member
    You need to use an indicator to see if the shaft is true. It's completely impossible to tell by eye.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • George76George76 Posts: 18Member
    I took it apart and:

    Recently installed motor was not spinning true--

    -It spun unevenly with or without new blower wheel, and..
    -while I couldn't detect shaft trueness, I looked inside motor and a disc-shaped component of motor was noticeably spinning untrue( with same pattern as blower wheel) ...

    HVAC tech who replaced it blamed on the old motor being loose and bending the motor mounts and housing, so when the new motor was installed, it immediately went bad since it was sitting in bad mounts/ housing.

    But that sounds questionable because the thing was reportedly pretty loud the very day it was installed. Wouldn't it take time for the motor shaft to go bad? Also, I noticed a dent on the motor housing.

    I ordered new housing and mounts and he is going to put another motor in it...
  • ChrisJChrisJ Posts: 9,896Member
    George76 said:

    I took it apart and:



    Recently installed motor was not spinning true--



    -It spun unevenly with or without new blower wheel, and..

    -while I couldn't detect shaft trueness, I looked inside motor and a disc-shaped component of motor was noticeably spinning untrue( with same pattern as blower wheel) ...



    HVAC tech who replaced it blamed on the old motor being loose and bending the motor mounts and housing, so when the new motor was installed, it immediately went bad since it was sitting in bad mounts/ housing.



    But that sounds questionable because the thing was reportedly pretty loud the very day it was installed. Wouldn't it take time for the motor shaft to go bad? Also, I noticed a dent on the motor housing.



    I ordered new housing and mounts and he is going to put another motor in it...

    It's hard to bend a motor shaft...........
    As in, I'd bet someone dropped it. It was bent when he put it in and if it's visibly bent, that's really bad.



    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Jamie HallJamie Hall Posts: 10,657Member
    Bad mounts and housing might bind the shaft -- but not bend it. The HVAC tech who suggested that either doesn't know what he's talking about -- or is trying to cover something.
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
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