Fan - suddenly full speed only

[SculptureOfSound]

So i was watching the fire tonight in my Montpelier when i heard a slight popping sound and then my fan speed suddenly increased from medium to full blast, and now the fan speed knob has no effect. i can still turn the fan off, but if it is on it is full speed in any position.

for someone not electrically versed, what can i check or replace to fix this? i assume its the rheostat but not sure if it can just be replaced with something off the shelf or would i need a VC part or what?

 

[MTY]

It most likely is an off the shelf part, but you will have to tear it apart to be certain. Do you have an owner's manual with the part listed?

 

[ShawnLiNY]

Remove and clean fan shafts and reoil bearings while changing speed control ( blower controls will burn out and fail faster when debris slows fan resulting in more electrical load at slower speeds ) the high speed is a failsafe ( automotive heater blowers are the same ) chances are the fan is not proprietary to Vermont castings so after removal you can cross reference the manufacturer or part #

 

[jetsam]

It could be a variable speed motor or a motor with four legs on the coil. Different controls are used for the two types.

I'd start by taking the speed selector out of circuit and seeing what it is and how it ohms out.

Might just be a rheostat or a four-position switch.

If you don't have a multimeter, you could try just replacing it, but it is not certain to be the problem.

You can just call the manufacturer for the part number and then google the part number to see what it is, and we can help you test it from there.

 

[SculptureOfSound]

Thanks guys. Not sure when I'll have time to take the fan out. It isn't hard to do, per see, but a pain as you have to lower the leveling screws (by hand with an Allen wrenches, a very slow process), then sort of wiggle/fight it out. Would be more inclined to do it but our dishwasher went on the fritz same day (ugh) so that needs to be addressed first.

Is there a way to control fan speed at the outlet end? Like a rheostat outlet or programmable rheostat? I'd love to be able to regulate fan speed either based on a programmable time setting (i.e. run on high for 2 hours after reload, then medium for 4 hours, then low after that) or based on external input (like the output of an auber stove thermocouple)

 

[SculptureOfSound]

Remove and clean fan shafts and reoil bearings while changing speed control ( blower controls will burn out and fail faster when debris slows fan resulting in more electrical load at slower speeds ) the high speed is a failsafe ( automotive heater blowers are the same ) chances are the fan is not proprietary to Vermont castings so after removal you can cross reference the manufacturer or part #

Will do. Had just cleaned it before this season but I don't know how old this is as I got the insert used.

Probably a basic question but what kind of oil do you use on the bearings?