How can I reverse this fan?

DaleB said:
AC motor, no permanent magnet, it will neither generate electricity nor impose much in the way of drag. Ever notice what a window fan does in the breeze? It freewheels.
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True
 
Put a planetary gear with a brake on the shaft.
 
Buy two fans. Mount them up facing opposite directions. Turn on only the one that rotates as desired. The other will windmill.
 
Salty said:
Is there a way to set up this type of fan to reverse it's rotation without disassembling every time. Disassembly to modify it is fine, but I want to be able to flip a switch or something and have it rotate the other way.

Alternatively, a different fan that is belt drive (quiet) no more than 36" (30 is ideal) that can be reversed would be even better. It does not have to be mobile because I will be mounting it permanently anyway, but so far, these are the cheapest I can find. But I've not found any that reverse yet at any cost.

1220312
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Not that it helps. But we use this fan in our gym to dry the floors after cleaning and cool
Off in the summer. Does really move
The air and is relatively quiet.
 
We had a turntable in our EMC lab at Intel in Dupont. Started out as a reversible direction single phase motor. Burned it out more than once, and the control circuits for reversing the starting windings were a pain. I suggested to the vendor that he replace it with a 3 phase motor. Made the control circuits much simpler. As noted above, all you have to do to reverse a 3 phase motor is swap any two phases. If you have 3 phase power available (and we had plenty) this is the easiest way to reverse a motor.
 
Ravioli said:
Buy two fans. Mount them up facing opposite directions. Turn on only the one that rotates as desired. The other will windmill.
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I considered that. Also unwieldy, but sadly probably the cheapest route for a quick implementation. I’ll probably just live with one direction before doing that.
 
There's a lot of Rube Goldberg style solutions here. Click Sac's link (well...just Google "reversing a single phase motor"). Follow some instructions relevant to your motor/situation. You'll end up adding some wire and a switch in most cases.

My neighbor has a bunch of single phase electric motors on oyster tumbling and conveyance equipment. He was going down a similar path trying to figure out how to make things reversible via mechanical means, and it literally took a light switch and some basic understanding of motors to get what he wanted. (Just have to flip the switch before you start... Once it's spinning, motor doesn't care).
 
I will probably end up putting a fan in both windows, one exhaust and one supply and just run the one pointing the direction I want. It doubles my costs, but it also lets me circulate with fresh air without opening the door.
 
Motor on my jointer, previously repurposed on something I needed the ability to reverse rotation.

Ignore the rigged up nature of the (re)install...but do note the two leads that are pulled up and wire nutted/taped off. Those previously went to a switch for reversing rotation.IMG_20190216_095359917.jpg

It's literally that simple. (ETA: looking at picture on my phone, can't see it as clearly as real life. It's two black taped wire nuts just left of capacitor...)
 
Salty said:
I will probably end up putting a fan in both windows, one exhaust and one supply and just run the one pointing the direction I want. It doubles my costs, but it also lets me circulate with fresh air without opening the door.
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I was about to suggest mounting two side by side, with a sliding door to block off the one you're not using. If your windows aren't right next to each other, your way might be better.
 
Turning the fan backwards is horribly inefficient and noisy. The blades are cambered and will be half-stalled in reverse. You're better off building your own fan with flat blades and a single-phase motor with a reversing switch.
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Can you access the connections to the windings without destroying the motor? Industrial motors often have a terminal block where you can configure the motor to run either way. If so you just need to wire in a switch to flip the polarity of either the start or run winding (not both!)
 
Half Fast said:
Can you access the connections to the windings without destroying the motor? Industrial motors often have a terminal block where you can configure the motor to run either way. If so you just need to wire in a switch to flip the polarity of either the start or run winding (not both!)
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These fans are typically made in Asia and they use the cheapest motor they can get away with, which would mean that it's unlikely to have any provision for reversing the start winding connections. That motor might even be welded shut, with two wires coming out through a grommet.
 
Dan Thomas said:
These fans are typically made in Asia and they use the cheapest motor they can get away with, which would mean that it's unlikely to have any provision for reversing the start winding connections. That motor might even be welded shut, with two wires coming out through a grommet.
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Maybe, but the fan I installed in our barn last year has screw terminals on the motor.
 
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