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How to reverse the direction of a 110v box fan

Lutiana

Lutiana

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I figure some of you guys out there may have an answer for me on this.

I have a box fan in my bedroom window. It is a pain in the ass to take out and reverse when it is hot outside so I want to be able to change the fan directions with a simply switch.

So here are my questions:

1. Is this possible?
2. How does one do this with AC? I know with DC you would simply flip the two wires, but I have no idea how to do this with an AC fan.
 
AC induction motors are manufactured to run in one direction. In small motors, such as window and desk fans, the shading (shunting) of a pole determines the direction.
 
Hmm, so I'd have to replace the motor. What type would you recommend that would allow me to switch direction and have maybe 3 or 4 speed in either direction?

I browsed through the wiki you sent me to and I have to admit I am a bit overwhelmed by it. Motors are not quite as simple as I had thought.
 
Surely you're not considering replacing the motor in a $15 - $20 fan with another that will probably cost you $50 to $75 or more for just the motor alone? And then you'd have to redesign the fittings on the new motor's mounts as well as the propeller fitting to the motor shaft. If you're looking for work... why not come over here and you can test some of these vintage parts I'm looking to sell. I'll even pay you. :)
 
I had a window fan at one point that had forward and reverse settings. I would think you might want to just replace your fan with one that is electrically reversible, like this one..
http://www.amazon.com/gp/product/B0001O2OKO/ref=s9_simh_gw_p201_d0_g201_i2?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=0FCZ4MRSVG53ERCF42H6&pf_rd_t=101&pf_rd_p=470938631&pf_rd_i=507846

Granted, that's not as fun as replacing the motor yourself..
Of course, if you're looking for a portable AC unit, I've got one I can sell you fairly cheap, and I live pretty close to you. :) I never needed it since moving to San Francisco, where it is cold and foggy all the time.
 
I'd probably just buy two identical window fans, mount them face to face and stick them in the window. Based on where you found them, it might be the cheapest way to go.

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This reminds me of the time my dad decided to experiment with building his own window fan. He had a half-horse (real, not peak or locked-rotor the way the fudge ratings now) motor kicking around, so he bought some fan blades and built a wooden box for the whole thing. He turned it on and then off, and it never saw power again--I think he got scared.

On the other hand, when I lived in Sunnyvale, I installed the largest attic fan I could find in my house. When you turned it on, your ears would pop. It was worth the money--it would change the air in the whole house every 30 seconds or so.
 
I think I'll just stick with flipping the thing around when I need to. This was mostly just flushing out the idea in my mind.

Ultimately what I was thinking was using an audrino or something like it to automatically switch on the fan and set the direction under certain conditions. But the more I think about it the less I think it would be worth it. I mean, it only gets hot enough out here maybe a dozen days in a year for this to really be of use.

A portable AC is not a bad idea, but it will have to wait till I get a job before I can truly justify spending the money. For now it will be cool showers and shorts in my 85F apartment and the window fans blowing the cool air in once it cools off outside.
 
lutiana said:
I think I'll just stick with flipping the thing around when I need to. This was mostly just flushing out the idea in my mind.

Ultimately what I was thinking was using an audrino or something like it to automatically switch on the fan and set the direction under certain conditions. But the more I think about it the less I think it would be worth it. I mean, it only gets hot enough out here maybe a dozen days in a year for this to really be of use.

A portable AC is not a bad idea, but it will have to wait till I get a job before I can truly justify spending the money. For now it will be cool showers and shorts in my 85F apartment and the window fans blowing the cool air in once it cools off outside.
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Check this out - http://www.homedepot.com/webapp/wcs...31234-2&srccode=cii_10043468&locStoreNum=2728
 
Chuck(G) said:
No, not really. One pays a premium for a capacitor start motor, as they're a bit more complicated. If you can see a starting capacitor, then I'm wrong--but I'm betting that there's not one there.
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You'd probably win that bet. I've had quite a few fans apart to unseize and oil the bearings and/or replace the thermal fuses that go when they seize; in my experience all box fans except one had six-pole shaded-pole motors, not easily reversible unless you turn the stator (or rotor) around).

But one of them and all the table-top and pedestal fans (that need extra torque for the oscillating gearbox) that I've run across did have start/run capacitors, so they should be reversible (although it'd probably take more than a simple SPDT switch if you want more than one speed). I've got a couple waiting for new fuses; I'll have to try reversing them when I get a round tuit.

AFAIK motors meant to be easily reversed like those in ceiling fans have two completely separate windings.
 
MikeS said:
AFAIK motors meant to be easily reversed like those in ceiling fans have two completely separate windings.
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I think you're right. It's probably cheaper that way.

Remember the old clocks with synchronous motors and the little shaft you gave a spin to get the motor started? You could spin those backwards and they'd work just fine.
 
Try an air conditioner. Then a flip of the switch will work, lol.

How about a cheap ceiling fan. They have a switch you can flip to make it rotate the other way. Just need to box it in and mount it somehow. Nothing is easy these days. Gotta spend $$$ or suffer.
 
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