Variable Speed Fan

[TimberWolf530]

I have this blower on my Englander NC30 stove. It's the standard blower that comes with the stove. Its located in my fireplace, so I didn't have room to mount it on the back. I built a plenum out of sheet metal with a 90 degree elbow that let me mount it on the side. Anyway, that doesn't have anything to do with my question. I was more explaining the picture. My question is, the way it is set up, it will not do variable speed. Its either on full blast or its off. It does not work with a fan speed control box. Is there anything I can do to modify it so it will work with the control box?

 

[babybart]

If the motor is a variable speed motor then just wire in a rheostat, preferably on the outside of the surround so you can actually use it.

 

[anlrolfe]

There's more to making a motor variable speed than just a rheostat...

 

[anlrolfe]

If the motor is a shaded pole design a simple plug-in, in-line motor speed controlled can be had for not too awful much money.
Don't cheap out and use a dimmer, they won't stand up to the starting current for extended time, get the real deal designed for motors.
https://www.google.com/search?q=plu...W11b7XAhUG7YMKHZNmCPsQsxgIKA&biw=1600&bih=964
just make sure it can handle you motor HP rating
probably only 1/16 to 1/64

 

[TimberWolf530]

If the motor is a shaded pole design a simple plug-in, in-line motor speed controlled can be had for not too awful much money.
Don't cheap out and use a dimmer, they won't stand up to the starting current for extended time, get the real deal designed for motors.
https://www.google.com/search?q=plu...W11b7XAhUG7YMKHZNmCPsQsxgIKA&biw=1600&bih=964
just make sure it can handle you motor HP rating
probably only 1/16 to 1/64

I bought one of those fan controllers, but it doesn't work. What is it about the motor that won't allow it to be slowed? Some of the motors designed for inserts with the square casing say they can, but none like the one I have says it can. I'm not experienced at circuit board work, so I'm not sure I want to tackle that project. If I could find a motor that I could buy that I could use a rheostat on, I would buy it. Every one I see says it cannot do variable control, even at Grainger.

 

[Wood Doctor]

My stove, vintage 1987, has a 2-speed blower switch that seems to still work. But, continuous variable speed controls are notoriously defective, primarily because of rheotstat failure. And, the blower bearings tend to dry out, lock up, and require servicing. That means removing the blower and spending several hours fixing it. I did this several times.

As an alternative, if you are running a stove that has a hot horizontal surface, consider a fan that runs on heat alone, rests on the stove top, and does need need a switch or electricity. After two years, mine is still working. I was surprised at how well it sends out heat to the rest of the room. It's also much quieter.

 

[TimberWolf530]

I actually tried one of those stove top fans, two actually and both stopped working after a month or two. This is not a problem with a defective rheostat, it is that the fan is not designed to be capable of using a rheostat. An earlier post gave me a circuit diagram to add to make it work, but I think it is beyond my abilities to make one, so I guess I'll just deal with it at full blast all the time. It actually has two speeds, but I can't really tell any difference between the two. Maybe I could modify the "low" speed setting to slow it down more????????

 

[Wood Doctor]

I actually tried one of those stove top fans, two actually and both stopped working after a month or two. This is not a problem with a defective rheostat, it is that the fan is not designed to be capable of using a rheostat. An earlier post gave me a circuit diagram to add to make it work, but I think it is beyond my abilities to make one, so I guess I'll just deal with it at full blast all the time. It actually has two speeds, but I can't really tell any difference between the two. Maybe I could modify the "low" speed setting to slow it down more????????

Well, I guess I should knock on wood that my heat-activated fan is still running atop my Federal Airtight stove. It seems that a fan control switch would work for you, wired in a separate control box. This would be similar to a ceiling fan control switch. They usually have three speeds. You may want to place a call to an electric company who could advise you further.

 

[NSMaple1]

On topic but not really : what would be the simplest way to variable or multi speed a 120/240v single phase 1.5hp motor? It is running a fan so might be more on topic than I thought, but has nothing to do with a stove. We have a similar fan, that uses a 3 phase motor and VFD - was hoping there might be a simpler way though, and still use the existing motor. I was pretty sure it wouldn't be so simple as a rheostat.

 

[Wood Doctor]

On topic but not really : what would be the simplest way to variable or multi speed a 120/240v single phase 1.5hp motor? It is running a fan so might be more on topic than I thought, but has nothing to do with a stove. We have a similar fan, that uses a 3 phase motor and VFD - was hoping there might be a simpler way though, and still use the existing motor. I was pretty sure it wouldn't be so simple as a rheostat.

That's really heavy duty and high current compared to a small blower or a fan. Fans are usually less than 100 watts and one amp. You are talking about 15 amps or more. I imagine such a control exists but it's likely to cost about the same or more than the motor itself. You might want to check the Surplus Center:
http://www.surpluscenter.com/