AboutWill Babbitt Expertise Electrical MOTOR or APPARATUS trouble shooting, motors, electrical problems, repair of most any electrical/mechanical/electronic apparatus, OEM, AC, DC, Industrial Applications, Three phase, single phase failure mode, determining the root cause of the equipment failure BEFORE failure of the replacement, antique appliances, motors, fans, many ceiling fans/base mount fans, poor equipment performance, modifications, habitual failures, vibration, redesign, obsolete issues, collectible items restored, rewinding. Owner of EMR Repair Inc www.emrrepair.com
More information under Engineering/Motors
Experience Over thirty years and now owner of my own specialty repair shop, EMR Repair Inc., located in Kansas City Missouri, service@emrrepair.com, evaluation and repair of electrical/mechanical apparatus. Electrical and mechanical repairs, trouble shooting including, vibration and balance issues.
Organizations Former IBEW, EASA,
Education/Credentials 4 Year Technical School, Industrial College Credit and non Credit, electronics courses, experience in electrical apparatus, motors fractional to above 5000HP, other electrical apparatus, slip rings, sleeve [plain] bearings, lubrication, identification-no data plate, control components, service and sales
Awards and Honors Yes
Past/Present Clients Federal Government, National Weather Service, NOAA, Commercial Power Plants, Major Vehicle Manufacturers, Printers, Other industrial and Commercial Concerns
I tested three ceiling fans in my kitchen. Two of them were of the same model, and the third one even of a different company. All of them hum and vibrate big time. I was even testing them without the blades.
The on/off test showed that the humming is present only when there is power. As soon as I turn the power off humming disappears, and the fan turns quietly by itself.
Two of these fans cost around $70 and the other one is $80. I'm not sure if they have a cheap motor that will hum no matter what. I'm totally puzzled and I started suspecting that I have either too low voltage or to low amp in the cables (I'm planning on testing it tomorrow,) however I'm not sure if it is the case. The lights on the fan are bright and don't show anything special.
What can be the reason of this noise?
Thank you in advance,
Greg.
PS. The fan is NOT on a dimmer or a three way switch.
The first model is Hampton Bay's 44" Carousel II. The second model is Harbor Breeze's 48" Elite.
ANSWER: Greg,
Interesting and a great job of explaining the question! I am hoping that experts one day get to rate the questioner, it is darn hard to explain how to fix a brown box.
Nice job, you have already eliminated one of the possibilities, which is manufacturer.
Now, not to burst the bubble or anything, but be aware that the same fan, motor, oven, whatever can be private labeled, but I see where you are going and it is the correct way to look at this.
There are three fans in your kitchen? Do they all look the same? I am going farther with your lead, any chance the third fan is a private label? I would guess all fans in a kitchen would be the same style?
Maybe not, but leave no stone un-turned, without breaking your toe.
So let's assume there are two and one COMPLETELY different.
All three hum and vibrate violently?
Without blades they hum? Or do they still vibrate and hum [both] with the blades off?
I take it they hum and vibrate with all the blades on at the same time. but with the blades off, is the vibration still there?
A $70.00 or $80.00 fan should be silent other than air turbulence as far as I am concerned, but not always the case.
The hum COULD be a result of low voltage. The current is a result. It is a result of the voltage and the load.
The wire can only effect current if it is so small, it can not HANDLE the required current. That will show up as a voltage drop, no load at the fan connections.
The wire would be hot and drop voltage via heat. Like a resistor wire, not exactly the same thing, but close enough to deal with this issue.
So your voltage checks are a great idea. You want to know what the voltage is with the fans off, and if possible with them on.
This can be tricky so don't get yourself hurt trying this on a step ladder, make sure you can do this safely or forget it, we will go another way.
Next your idea of current is great, and they are selling clamp on meters in stores now, where years ago no one had one. Same thing, if you are up there clamping the current reading, be careful.
So if you can get your hands on an amp meter, we want to know, if the current with fans running, is what the nameplate calls for.
Have the fans vibrated and made noise forever, just recently, or have you been living with this problem for some time?
The humming is electrical in nature, nice job again.
And each fan is independently controlled? You say "by itself" so I assume that each quiets down with it spinning centrifugally, no power.
All speeds, on all fans, are just as much noise and vibration? Either together or independently energized?
Do you know who hung the fans? Ceiling mount or drop bar?
Are all the fans on the same circuit? What I mean: are they all on the same circuit even if they are switched independently?
They all have light kits, wall controlled or cord?
Vibrate big time......that one I need you to tell me more.
Does the vibration stop when the fan [s] are de-energized?
Or just the hum?
A few things to think about:
Voltage and current readings are perfect to solve this if you can do it safely!
How close are the fans to each other?
Are they mounted to the same structure? Three in a row on the same beam?
Blades on:
Does the severity of the vibration change when one is on, two are on, three are on?
Are all the fans rotating in the down direction? Or up direction, or mixed?
Because the lights seem bright, it would be my guess you would know there is low voltage, but motors are such picky devices, some with low voltage run better, some run worse with high voltage.
The blades on or off could be wind turbulence creating vibration, or structural vibration, where the natural harmonics, are resulting in more vibration due to the same structure reacting in an unwanted motion.
[The heavy side of one blade is rotating in sync with the heavy blade of the other two] sounds weird but it can happen.
The motors when running will generate a back emf and harmonics, that is way too complicated to deal with here.
But that is why I want to know if the fans are on the same breaker.
What I think you are going to find is a combination:
Fans are cheaply made and have what most fans have, and that is hum from the way the motors and fan assembly are made........times three.
Maybe the hum is now on the same beam and creating even more noise through amplification from that same beam.
[it becomes like a tuning fork]
The motors are on the same circuit and the voltage is low, not enough to know by looking at the light, but the motor is not handling the low voltage very well.
I need history with blades on and off, operating at the same time and one at the time, and if you get current readings, what they are on all fans.
Great question well thought through, and with some more investigation, we will probably find the worst of it is the hum, in the fans is natural, to the motor, and you have three of them in close proximity of each other.
Combine that with two many fans and lights on the same circuit, air turbulence fighting each fan, and structural harmonics from improper or incorrect installations.
Let me know as you get more data and give me some history.
Double check rotation, make sure they are all the same direction, change one,, change two and see what, if anything that changes.
One more, anything else on the same circuit?
Will
---------- FOLLOW-UP ----------
QUESTION: Hi Will,
My first answer will immediately show that you were overestimating me ;)
I have only one place for the fan in the kitchen. What I wanted to say is that I was physically replacing fans three times already.
I guess it will answer several questions of yours like distances between fans.
All of them were humming and vibrating. Vibration is not visible. What is interesting is that when I grab the (not rotating) bottom of the fan, it still hums and now, one can feel the vibration. I'm not sure if the humming comes from vibration or from the transformator, but what I experienced is that when I turn the power off, both humming and vibration cease. The rotating part of the fan still keep freely and quickly rotating without any noise.
Yes, after encountering the issue with the first fan, I started doing the tests without the blades without any difference in the fan noise. So, in other words, the fans hum and vibrate without the blades on.
I have measured the voltage, and it is 125V. I have tested the voltage at the light fixture cables as well, and the voltage is the same - 125V
The house is old, however the wires in the kitchen are newer than the wires in the bedroom, where I installed an other (10 years old) fan which is quiet like Winter night.
The cables seem to be all right and the visual inspection does not show any reason why they would be too small for the job.
After installing the first fan, I left it for a while without testing it, and assuming it has to have a break time. Only after some time I gave up on it and decided to replace it. In other words, the noise was from the day one.
The noise level is proportional to the speed. The higher the speed the bigger noise. The slowest speed still makes the noise, and keeping the fan's bottom with the hand does not eliminated it.
It was me who was installing the ceiling fan and the ceiling box. The box is screwed to the ceiling with two 2.5" screws (it's a two family house and we're living in the lower level.)
All the fans have light kits and they are controlled with the on/off switch on the wall.
Yes, both the vibration and humming stops when the fan is de-energized.
The noise is in both cases - when the fan rotates in the down and up directions.
Pushing the ceiling up, or pressing the fan to the ceiling doesn't change the noise volume too much. I understand that the beam the fan is attached to can react like a tuning fork, but the noise should cease as soon as I press (change the wave length) the fan to the ceiling (the same as with touching the fork with the hand.)
Currently there should not be anything on the same circuit unless there is something I don't know of (how can I test it?)
Thank you very much for your time, Will
Greg.
Answer Greg, I don't think I over estimated at all, the diagnosis is even better this time.
I can see now where the mix up on three fans could happen, and should have caught it as comparative.
So you have the box mounted firmly, the voltage is right on the money, and the fan still makes all this noise.
Changing the physical structure has no effect, so you are right about that.
To tell if the fan is on another ciruit will be to kill the breaker of the fan and look for other lights to be out, and test each outlet for voltage, unfortunately it is that kind of hunt and search job.
I wouldn't go there right now, as you have 125 volts and that is plenty.
Pressing the fan to the ceiling, tell me what that means exactly.
Are you saying putting pressure on the fan enclosure to the ceiling or is part of the fan actually moving to the ceiling?
It sure sounds electrical in nature, you have done what really good vibration techs do, cut the power and look for a change in amplitude.
It seems like a BIG change in amplitude.
any possiblity or is this just a huge job..........can you mount the silent fan in the kitchen temporarily?
that would tell you a bunch, but could be a big job to dismount and remount.
There is no down rod I take it, it is a ceiling flush mount?
Usually they come with optional down rods.
Any chance of mounting it by down rod? just to see what happens?
Or another thing you could do. Make up a lamp cord with a switch.
Plug it in a wall outlet and hold the fan by the down rod.
with no blades it should not torque much. but the bearing assemblies will require the fan to be tested with the shaft down, it can't be turned up side down.
It sits on a thrust bearing or thrust is handled by the bearings in some manner.
Maybe a wood cradle of some sort and set it on a flat floor.
I think you have three fans not of the quality of the bedroom fan.
I gave up on 80.00 fans period, every fan I have in everyroom was well over $200, and some well over twice that.
I hate to say it but most of the 79.99 stuff is crap.
It is either hung wrong, and the torque when energized has some unbalanced plane to fight, or the cheap multi pole motor is just that.
you have the voltage solved, it is at 125. frequency is not wrong or your clocks would run fast or slow or and other things would act real weird.
The cable or wire is not dropping voltage, and if something is back feeding this fan is something of some size and probably motorized.
I just doubt it.
Tell me about pushing the fan to the ceiling, I am curious about that.
You are doing great and I think we will find a cheap fan that is just how they sound.
I had them and that is why I refused to ever buy another one. They hummed and the cord bounced and swung, just junk.
so there are some suggestions, temp wire it somewhere else, that takes care of everything, if it still sounds like crap it is crap.
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