# Electric motor question?



## pjf134 (Aug 4, 2011)

I have a big fan (see pic) it was 1 1/2 HP 3 Phase and I put a 1 HP single phase on it and was wondering if there is a way to slow it down some, since I do not want to suck in the walls while in use. It does move some air quick, it's 24" dia. tube fan with turning vanes inside it. Is there something I can do to make this work for me without getting into a DC motor? I am looking for something simple and cost effective naturally. I do have some smaller motors, but I think it will overwork them.
 Paul


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## Tony Wells (Aug 4, 2011)

The most straightforward approach is to change the drive and or driven pulleys and belt.


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## pjf134 (Aug 4, 2011)

Thanks Tony,
 I would like to put a reostat on it, but that would require a DC motor I think. What size DC motor would work with that beast? How far are you from American Standard HVAC plant in Tyler? A couple of guys from my wife's work went there last week and they said it took them 3 hours from the airport. I know Dallas is closer than that, unless they flew into Houston.
 Paul


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## Tony Wells (Aug 4, 2011)

I can be at that plant in about 20 minutes. It started out General Electric, then Trane, then Ingersol Rand owned American Standard (if I have all the right). I have a cousin working there, as a career. I stupidly passed up a job right out of HS in their model/prototype shop. Still kicking myself for that after all these years. I would be retired, fully, by now.

If the guys flew into DFW Int'l, 3 hours is not too far off. It's on the north side of DFW, and it's probably 130 miles or so to Tyler, and the plant is on the SE side. If they came into Houston, it's 3 1/2 hours just to get to Tyler. Likely DFW.

Well, horsepower is horsepower, so it still would take the same size motor. Sounds like more work to swap motors than pulleys to me. A rheostat would have to be quite large (and rare) to directly control a large DC motor. Got a junk treadmill?


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## Pacer (Aug 4, 2011)

You dont say what the RPM of the replacement motor is - hopefully it isnt 3300? Probably not, I doubt a 1hp 3300 would pull that big boy - or it'd take off and fly!

Looks like you could go down on the motor pulley size a bit


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## pjf134 (Aug 4, 2011)

The motor on it now I think is 1725 rpm, I did have that motor on my SB9A for awhile until I put the drum switch and reversing motor on it, I had to make a adapter for the pulley, 3/4" to 5/8" for it to work. I do know where a motor is that might work, it's on a heavy stationary bike that weighs a ton. I was thinking about getting it and using it for a slitter, but people were telling me that it would be a pain to do. It has a slider speed control on it with I think was a 1/2 HP motor. The bike was used for rehab and not for exercise and it does work great and is like new. It's at my shooting club and free, nobody wanted it for the last few months so I guess I will try it, if it's still there. The fan is well balanced and blades move real easy by hand with very little effort so it might work ok.
Tony,
 Tyler did not look that big on the map it just looked close to DFW airport. I do believe American Standard address is Tyler and is owned by IR. My wife's company is a distributor for AS since may since Comfort Maker put the screws to them. There are also a distributor for Mitsubishi HVAC products.


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## Tony Wells (Aug 4, 2011)

1/2 hp might be a little light. That depends on the speed desired out of the fan. Naturally, the faster you want to spin the fan, the more hp it required. If you do convert to the DC variable motor, keep an eye on the motor temp, and current draw if you can. A clamp type ammeter won't read correctly on a PWM circuit, so you'd have to rig up another method. Probably not worth the effort. Just watch the temp.

Tyler hit right at 100k this last census, so it's not a big city by any means, but it's lost much of it's small town charm, to me anyway. I was born and raised here. I live out in the sticks now, and don't go to town unless I have to.

Comfort Maker....Carrier, right? We have one of their plants here also.


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## Pacer (Aug 4, 2011)

I also would think a 1/2hp is not enough for that fan. If it is a 1750rpm and sucking the paint off the walls, it may have originally had a 1100-1200rpm type motor on it. Ive worked in a couple places that had those big 48" fans and while I never noticed the motor, It was apparent the blades werent turning very fast.

I have adapted some 8 or 10 treadmill motors into different applications with varying results. One, two and three HP on them is kinda like Chinese horses - a bit exaggerated! While a fan wasnt one of my uses, I have reservations about one working in your application. I have one on a small lathe and a drill press that are great, but one on a converted wood band saw to metal, its not so good. Another on a 2x48 belt sander I made wouldnt even begin to drive it. I suspect one will overheat in your fan.


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## pjf134 (Aug 4, 2011)

Tony,
 Carrier bought out Comfort Maker a few years back but up here they dealt with the Tenn. factory, closer I guess. I would like to slow down the fan to a slower speed so my new paint on my lathe does not get sucked in the blades, it moves some air with the 1 HP. I did throw a rag in the air 6 ft. away and it sucked it onto the grill, so a slower speed would be better for me. I do have a 36" industrial fan, but is to big for my window. As you can see in the pic I did a figure 8 on the belt to make it go in the right direction as discussed in a previous post when I had that 1 HP motor on the lathe, the one with the broken cap. I would like to reverse it but rewiring it is not my thing.
 Paul


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## Tony Wells (Aug 4, 2011)

Easiest thing would be to get a smaller motor pulley, and/or a larger fan pulley and longer belt. Probably less than $20.

Or, if you're really adventurous, change the pitch on the blades.


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