Wood Stove Insert convection: loud buzzing

[Amin1992]

Hey guys. Bought a home with a Heatilator ECO Wins 18 wood stove insert that has a built in convection fan.

I was not planning on using the fan because it is really loud and when on makes a loud, electronic-sounding buzzing sound (kind of reminds me of the sound of those fluorescent lights in a factory if that rings a bell).

I thought maybe this was just the nature of the fan. However I'm seeing other units online in videos that just sound like a fan. Likewise, I took the panel off to look at and clean the squirrel cages, and as soon as I turn the fan off, the buzzing noise stops, even though the fan blades are still spinning.

That makes me think it is something with the motor itself and not the fan.

Anyone have experience with this at all? A new motor is $300, and the insert is from 2017 so no warranty unfortunately.

If anyone has any suggestions let me know. Thanks !

 

[begreen]

It sounds like the buzzing may be from a loose component or maybe the grille itself? Or the grille could be adding just enough resistance to unbalance the fan?

Have you removed the blower and cleaned the blades thoroughly? That is often the source of an out of balance blower.

 

[Amin1992]

It sounds like the buzzing may be from a loose component or maybe the grille itself? Or the grille could be adding just enough resistance to unbalance the fan?

Have you removed the blower and cleaned the blades thoroughly? That is often the source of an out of balance blower.

Thanks for the response. It isn't from the grill, as I ensured that the 3 contact screws had proper rubber padding between. Doesn't seem like the fan is unbalanced as I even detached from the metal grill and plugged it in, still buzzes...

Not sure if it's possible to open up the motor and fix a loose component. Nothing I can see though from the exterior...

 

[begreen]

Is there a motor speed control on this blower? A faulty one can cause a motor to hum. Does the blower buzz at full speed?

 

[Amin1992]

Is there a motor speed control on this blower? A faulty one can cause a motor to hum. Does the blower buzz at full speed?

Yes there is a speed control! In the manual it's called a rheostat.

It's hard to tell if it's buzzing at full speed because the fan is so loud!!

Do you think that could be it? I could order one for around 40 bucks and I think I could swap it myself.

 

[begreen]

I don't know the stove well enough nor what you are hearing vs a new insert of the same model to comment on this. A Broan fan controller is about $22 on Amazon.

Are there lubrication ports on the blower motor?

 

[spudman99]

A consistent buzz that remains mostly the same sound level and does not change much is indicative of an electrical issue. Rattling and clicking are normally from mechanical issues, and will deviate in tone and frequency when the motor speed is increased or decreased. Motor hum is mostly from the windings passing by the magnetic field and can be caused by several issues. Most cannot be fixed even if you open up the casing. A rheostat modulates the power input to speed up or slow down the motor. Rheostat will usually buzz when going bad and there may be a click or snap when turning on or off.

If you are able to, maybe pull the fan from the insert, and rig up a connection to see if it still makes noise.

 

[ckr74]

They all make a sort of buzzing noise. It's a frequency of 60 hertz. Some motors are insulated better between housings and motor so you don't get the buzzing noise as bad. I always suggest going to DC motor if you can then no more buzz.

 

[Amin1992]

I wanted to share a video of the noise. It just doesn't sound right. I have a pellet stove in another room and that fan is perfectly nice and quiet. No buzz or hum.

Here is my insert and the noise. Is it normal?

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[Amin1992]

Wanted to post an update. I briefly held onto the squirrel cages to stop it from spinning, and turned the unit on. The electric buzzing noise is 100% coming from the motor itself, so lubrication and cleaning of the fans is not the solution here.

For the time being, I've decided to treat my unit like an old school stove and just not use the blower fan, unless anyone can come up with any idea on what is happening. I could replace the fan but it looks like they cost over $300 which is just not worth it to me.

Thanks everyone.

 

[Mech e]

I like Spudman99's suggestion of bypassing the rheostat to see if the noise goes away.

 

[Amin1992]

I like Spudman99's suggestion of bypassing the reostat

Im going to try that when I get some free time. The rheostat itself was quiet, only the motor hummed away but maybe that is still caused by the stat.

Will post back when I can

 

[begreen]

Might just be the recording, but that didn't sound too obnoxious. Motors usually can be lubricated. The blower fan in most of these small fans has no bearing or lube point.

 

[Amin1992]

Might just be the recording, but that didn't sound too obnoxious. Motors usually can be lubricated. The blower fan in most of these small fans has no bearing or lube point.

Ya I noticed the recording seemed to make it sound a lot quieter even though it captured the noise. I could hear it over the TV at a normal volume. I know I said it before, but only thing I can compare it to is the loud buzzing of a workshop fluorescent light. Also sounds like a fridge compressor but twice as loud.

I ended up just tucking the cord in behind the trim and planning on not using it. If I change my mind I can always get it back out and look into fixing it. Thanks for the help

 

[ckr74]

I guess you could get a small table top fan and blow air at it. They're usually fairly quiet.

 

[Amin1992]

I guess you could get a small table top fan and blow air at it. They're usually fairly quiet.

Exactly what I'm thinking, or even just a fan in the room somewhere to move air. We dont have central AC and wont be using window units on this floor so will probably have a fan anyway!

 

[Mech e]

The thermal efficiency of an insert is greatly decreased without the use of a blower. Think about turning the heat on in your car and not running the fan, or what happens to your engine if the water pump quits.

 

[Amin1992]

The thermal efficiency of an insert is greatly decreased without the use of a blower.

I know. Not trying to heat an entire home with it, just a room about 200 sq ft or so

 

[Mech e]

I know. Not trying to heat an entire home with it, just a room about 200 sq ft or so

Understood, but you will consume less wood with the blower.

 

[Amin1992]

Understood, but you will consume less wood with the blower.

I was a week away from converting this back to a traditional fireplace, so I feel like even using an insert w/out a blower, I'll be more efficient and use less wood than I would have had I gone the traditional route!

 

[SidecarFlip]

Go to your friendly ACE hardware store and get an assortment of soft rubber grommets and replace the hard ones between the motor and the fan housing. You need to isolate the motor from the sheet metal housing. Simple fix. Might need new fan bearings as well, also simple fix.

 

[Amin1992]

Go to your friendly ACE hardware store and get an assortment of soft rubber grommets and replace the hard ones between the motor and the fan housing. You need to isolate the motor from the sheet metal housing. Simple fix. Might need new fan bearings as well, also simple fix.

Unfortunately it is not this simple for me. I actually removed the fan assembly from the stove. I also temporarily jammed the squirrel cage fans to test this. Even when the fan is not spinning at all and not attached to anything, the buzz is happening, and I pinpointed it specifically to the motor. Electricity off, instantly stops. Flip the switch on, instant buzzing regardless of fan speed or lack thereof.

 

[SidecarFlip]

Unfortunately it is not this simple for me. I actually removed the fan assembly from the stove. I also temporarily jammed the squirrel cage fans to test this. Even when the fan is not spinning at all and not attached to anything, the buzz is happening, and I pinpointed it specifically to the motor. Electricity off, instantly stops. Flip the switch on, instant buzzing regardless of fan speed or lack thereof.

It's a shaded pole (induction) motor and as such, the laminations acting on the armature will produce harmonics relative to the cycles per second the controller (rheostat) is feeding it. No way around that except effectively isolating the motor from the fan (sheet metal) body, which amplifies the harmonics. Just do what I told you do to. That will reduce it appreciably. Your grommets have hardened with age. Real typical.

Detrimental to the motor to lock the rotor like you are doing btw. Not so much with a shaded pole motor but is instant death with a conventional motor. Great way to discover the smoke from overheated windings.

 

[SidecarFlip]

Usually, if a convection fan is screeching or making a rubbing sound, the bearings need replaced which requires disassembly and the bearings pulled/pressed from the armature shaft and replaced. Back in the day, they used oil light (oil impregnated bronze bearings) but today they will be sealed ball bearings. Even the sealed bearings will eventually fail because they live in a hostile enviroment of heat and dust. Nice thing is, all bearings today will have a bearing number tatted into the outer race so it's s simple matter of buying replacement bearings with the same ISO catalog number.

There is really nothing to 'wear out' other than the bearings and sometimes the windings on the laminations will fail, but not very often.

 

[Amin1992]

It's a shaded pole (induction) motor and as such, the laminations acting on the armature will produce harmonics relative to the cycles per second the controller (rheostat) is feeding it. No way around that except effectively isolating the motor from the fan (sheet metal) body, which amplifies the harmonics. Just do what I told you do to. That will reduce it appreciably. Your grommets have hardened with age. Real typical.

Detrimental to the motor to lock the rotor like you are doing btw. Not so much with a shaded pole motor but is instant death with a conventional motor. Great way to discover the smoke from overheated windings.

Thanks for the tip. I'm a bit confused though. Since I took off the motor completely and it was just as loud without being near sheet metal, I don't think the rubber grommets are the culprit - they feel soft anyway.

And yes definitely not good for the motor, I just did it for a few seconds to confirm it wasn't the fan blades causing this noise.

Maybe it is the bearings but this is a bit beyond me I think. The housing doesn't seem to have anything to allow me to open it up, no screws or bolts of such. Almost looks like it's stamped together or crimped shut.

At this rate, I'd think about buying a new motor, but again it's $300. And I'm afraid that maybe this is just the nature of this motor as I know my model stove is an economical one. Maybe the cheaper motor just makes noise. I'm just not a fan.