Bathroom ventilation fan not working

[Vikas]

This one started making noise and now completely dead.

The noise felt like plastic fan hitting the duct-work which I was very familiar with from my experience with the other bathroom. Before I had a chance to open it up, it stopped completely. The motor no longer spins. as far As I can see, it is 4-pole sheded motor. I do not believe it has capacitor. The DVMM shows there is no longer continuity in the motor terminal. The sticker says "thermally protected". There might be one time thermal fusible link but nothing is obvious.

The easiest thing is to order this and swap the module.

But I hate throwing things out and of course I am cheap too! If I could find thermal protection, I could bypass it but do I want potential fire hazard hanging over my head in the bathroom?

The motor spins nice and free, so I know bearing is good. I could try to find the replacement thermal device if I can locate it but I don't think it is going to be cost effective. Besides, I would still have to figure out how to make sure the plastic squirrel cage fan stays put rather than moving on the shaft and hitting the duct-work. It took me months of fiddling and using JB-weld to finally convince the fan to stay put on the shaft in my other bathroom.

Any suggestions?

 

[The_Eric]

There's being cheap and there's being stupid. Don't be the latter. You're smarter than that!

 

[JTK]

Can you spin the inop fan by hand? Sounds like something jammed it up.

 

[Brad_C]

Needs a new hamster.

 

[michaelluscher]

Get a new one

If you have the wedge, one that's not builder's grade

Panasonic units on Amazon are $80~, but 80+ CFM, and very quiet

 

[JTK]

Panasonics are awesome. I installed 2 in our last home, but this was during some major bathroom re-work. Trying to retrofit a new fan w/out disturbing your ceiling might be an issue.

 

[Vikas]

Originally Posted By: Vikas
The motor spins nice and free, so I know bearing is good.

Originally Posted By: JTK
Can you spin the inop fan by hand? Sounds like something jammed it up.

Write-only replies don't help :-(

 

[bubbatime]

Penny wise and pound foolish is the term we are looking for here.

"ways my house can catch fire" for $1000 Alex.

 

[Brybo86]

short of buying a new unit..... maybe try calling the Broan manufacturer and complain...?

 

[Vikas]

I am disappointed in responses. I had already mentioned the fire hazard. I was expecting somebody to show how they were able to fix the fan unit without compromising fire safety. Where are the people who have curiosity to find how things work and to fix them when they are broken?

I already ordered the fan module and it is on the way but now I am going to take it as a personal challenge to figure out exactly what is wrong with the old one.

 

[javacontour]

You said it yourself, you have a new one coming. If you are interested "for science" by pass the thermal protection and test it on the driveway.

Then you'll know and can replace it with a new, safe fan.

 

[Oldmoparguy1]

Quote:
But I hate throwing things out and of course I am cheap too! If I could find thermal protection, I could bypass it but do I want potential fire hazard hanging over my head in the bathroom?

The motor spins nice and free, so I know bearing is good. I could try to find the replacement thermal device if I can locate it but I don't think it is going to be cost effective. Besides, I would still have to figure out how to make sure the plastic squirrel cage fan stays put rather than moving on the shaft and hitting the duct-work. It took me months of fiddling and using JB-weld to finally convince the fan to stay put on the shaft in my other bathroom.

Any suggestions?


Op is asking for help in locating the thermal device. My guess is that it is somewhere in the motor housing. That's where I would look. Look for something that looks like a fusible link, or maybe looks like a diode encased in a sleeve. I would likely do the same thing. I have autopsied all sorts of un-reparable consumer grade stuff, just because.

 

[Quest]

@op:

The thermal fuse (which is blown BTW) is hidden somewhere along within the motor winding itself. This is somewhat similar to that of CSA requirements, which is somewhat common for motors of this sort (don't come along and compare to those so-called "ETL certified" chinese fan crabp that you get from big box store---they don't come with any form of protection BTW.

Your best bet in this case is to find a replacement motor (instead of unwinding the already dipped motor winding, which will cannot be re-wound afterwards due to insulation breakdowns).

Good luck.

Q.

BTW: I'd buy panasonic fans instead...they last considerably longer, performs better, quieter, and more energy-efficient.

 

[sleddriver]

The thermal fuse is located inside the motor winding. You can attempt to unwind it if you wish. Odd that it opened up with the shaft spinning so freely, but these things do happen.

 

[Vikas]

I do see something enclosed in a sleeve between winding poles.

I would have loved to get the Panasonic fan instead but it would require lot more work to swap the entire unit. I was sort of looking at this as the opportunity to do a full replacement but the OEM replacement fan module (shown earlier) shipped to my house was ridiculously inexpensive and will need less than a minute to swap.

 

[dishdude]

I prefer to stick with Braun/NuTone because they make the same unit for decades, replacement parts are easy to come by and cheap!

Their better units are really good, but most have experience with the loud and cheap builder basic 6 sone 50 cfm units.

 

[wrcsixeight]

I did not realize bathroom fans were such LOW CFM units.

A bathroom I recently worked on has a window only 11 inches tall but at the very height of the ceiling.

I powered a 230MM 12v computer fan (BitFenix Spectre Pro 230mm) through a 12vDC transformer/powerbrick/wall wart, and made a Plexiglass shroud for positive air displacement. I wired it to come on with one of the two light switches.

Very low electrical consumption.

It is rated at 156CFM and is very Quiet and can open the 80 LB door if the lock mechanism is not engaged.

The owners love it.

 

[Kiwi_ME]

Well, they're low CFM because they normally use radial flow blowers which have a more useful pressure ratio instead, with less noise than an axial flow fan. In my last home I installed a 5.25" rack-mount industrial blower in the ceiling which gave me an impressive 600 cfm.
I had thought the original Nutone fan had failed but in fact the builder had neglected to remove the plastic cover over the fan outlet before attaching the vent pipe - 20 years earlier when the house was built.

 

[Brad_C]

Originally Posted By: Vikas
I am disappointed in responses. I had already mentioned the fire hazard. I was expecting somebody to show how they were able to fix the fan unit without compromising fire safety. Where are the people who have curiosity to find how things work and to fix them when they are broken?


As others have already mentioned, the winding is protected by a thermal fuse which is usually buried in the winding. Of course it can be repaired, and in fact un-winding and re-winding (with new wire) motor windings is performed every day. I'd love to teach you how to do it because it's not difficult. It is time consuming, and by the time you procure the wire probably quite expensive. The biggest concern is that if you have to ask how to do it properly on a motor oil web forum, you probably shouldn't be doing it at all.

If I were doing it now, I'd dismantle the motor to get out the bobbin (often quite a task), mount that on a mandrel in the lathe and wind off the existing winding. Count the turns off and note *where* the thermal fuse was. I have a simple hall-effect counter on the mandrel to make that easier. Make a note of any special insulation or layering detail. Calculate the length of wire required from the turns and bobbin diameter (or lay it out on the ground in multiple lengths and measure it), and measure the wire diameter with a micrometer accounting for insulation thickness. Procure replacement wire (usually in minimum order quantities of about 10 times what you actually need) and a replacement thermal fuse. Re-assemble in the reverse order it came apart.

Much easier to re-wind a shaded pole motor with a single bobbin than to re-wind a normal motor stator, although usually the bobbin is held in place by either a welded or riveted section of lamination and can be hard to get out without totally destroying the assembly.

All in all, about a days work. I love a challenge as much as the next guy, but you need to learn to pick your battles. I've re-wound plenty of stators, solenoid coils and transformers where replacements were either prohibitively expensive, or simply unavailable. I don't think I'd bother with a $50 exhaust fan. If its a common enough motor, I pay a re-winder to do it. They are geared up for shaped stators and can do it much faster and cheaper than I can.

Never re-use winding wire. Kapton tape makes a pretty good replacement for ancient insulation, and waxed paper is still available from any place that makes custom transformers.

 

[spasm3]

I would replace it unless its a high end fan. Most builder grades move little air. I would get a nice panasonic high cfm fan. If you have a bathroom in a downstairs setting, say off a living room or garage area, you want a louder fan to cover up sounds when company is over.