squirrel cage fan

bookman51 · Jul 5, 2010

Only slightly off topic, but I have wired up a squirrel cage fan off an old furnace to use in my shop. I shut it off Friday and then it would not start on Saturday. I did not see any wires loose going into the fan, and I am getting electricity to the fan.

Anybody want to help guide me to the problem. I figured it would run forever...more or less. Kicks out lots of air and is nice to keep some air in motion in a warm shop.

I do not recall how I wired it...been maybe 8-9 years ago...but there are lots of wires coming out of the fan. It is 110 volt.

Thanks in advance

Bookman

lilredex · Jul 5, 2010

First thing I'd look at is the "re-set" button on that motor. If you worked it really hard it could have tripped it.

If OK, take off the belt and see if the motor will start on its own. Twist the shaft to get it going, maybe. If nothing, get a test light on that motor to see that it actually has power, then work back from there.

If the red button tripped out, you may want to slow down the fan a bit. Most of those motor pulleys are adjustable, ie, one side is locked with a set screw and unscrews to make it wider or thinner depending upon your need.........wider a turn or so in your case.

ddawg16 · Jul 5, 2010

Pulley? I'm willing to bet that it's direct drive.....but as lilredex said....see if it has a reset button....

Double check your wire nuts....I assume you already made sure that it was turning freely?

Is there any hum when you apply power?

Does it have a thermal OL switch?

And....how did you verify you have power going to it? Did you measure it with a meter?

If you do have power...then ohm out the windings...if it's open....new motor time.

And just in case anyone is wondering....squirrel cage fans are great for moving air....they have the advantage over a typical bladed fan in that they can create a lot more static pressure....a bladed fan can move a lot of air over a large area....but they have poor static pressure....(excluding airplane props) Squirrel cage fans are really good at moving air through ducts....

If you want to regulate the air flow....just put a restriction at the inlet....the motor will just speed up a little and draw less amps...won't hurt it.

lilredex · Jul 5, 2010

ddawg16 said:
Pulley?

Made that assumption because he said old furnace.

If you want to regulate the air flow....just put a restriction at the inlet....the motor will just speed up a little and draw less amps...won't hurt it.

Actually the prefered way is a gate on the outlet.

Elroy · Jul 5, 2010

Could be the starting capacitor has gone bad.

Is this a multiple speed motor??

bookman51 · Jul 5, 2010

Hey, great help. I have been gone for most of the day. Need to do some checking. It is one speed....and no hum when plugged. I think direct drive with no belt but I need to check.

I enclosed it maybe 8-9 years ago with a wood box. I have a filter furnace at inlet and then a screen over the outlet. I wanted to make sure no little (or big) fingers got in the wrong spot.

Yep, does move some air. A heat/air conditioning place I used to do business with just gave it to me (I probably paid for it somehow--I did purchase a new heat pump from the fellow). The owner hated to toss stuff, and I had a use. In fact, he gave me an old trailer house furnace for which the air conditioner part had gone bad, and I put in my shop I had at the time. I think the fellow even shaped the tin for free. Wished I had not moved 4 states away from him.

I will do some checking on the fan and get back with folks.

Thanks again.

Bookman

Torque1st · Jul 6, 2010

lilredex said:
Actually the prefered way is a gate on the outlet.

I always used the inlet restriction because it lowered the amp draw. An outlet restriction will raise the amp draw as static pressure increases.

In a normal furnace the inlet is restricted due to duct work and filters. The restriction allowed the manufacturer to use a slightly larger blower or faster blower speeds for a given size motor. In free air the motors in that type of application will overheat and pop the reset or burn up without some inlet restriction or mechanical speed reduction as in a belt drive.

bookman51 · Jul 6, 2010

Torque1st, My squirrel cage has the motor in the middle of the fan. I wonder from what you wrote (see below) if I did something wrong. The only retriction is a filter furnace on one side that ***** the air into the filter. I need to take the top off the wooden box I have it in to find a reset button (that would be the easy fix!!).

Thanks

Bookman

"In a normal furnace the inlet is restricted due to duct work and filters. The restriction allowed the manufacturer to use a slightly larger blower or faster blower speeds for a given size motor. In free air the motors in that type of application will overheat and pop the reset or burn up without some inlet restriction or mechanical speed reduction as in a belt drive."

Freejack · Jul 6, 2010

To the OP, check the capacitor, I'd be willing that it has gone bad.

Torque1st said:
I always used the inlet restriction because it lowered the amp draw. An outlet restriction will raise the amp draw as static pressure increases.

In a direct drive blower with an induction motor restricting either the inlet or the outlet will decrease amperage, as both reduce the amount of work the blower wheel is able to do.

For the OP, there is probably enough restriction in just the filter to ensure the motor is operating within it's rated zone. It's easy to check with an amp meter, the measured amperage should no more than 10% above nameplate. If it is too high, and this is a multispeed motor, just step down a speed tap and it will work just fine.

Jake

bookman51 · Jul 7, 2010

The capacitor is good. Had an electric shop check it. They said probably just a short somewhere. I am in the process of trading out the motor and get a used one from a local heating/plumbing shop. They have a bunch of motors taken out of old fans. Maybe I will get another 10 years from a used motor.

Thanks for the help.

Bookman

Torque1st · Jul 7, 2010

Make sure you check the current when you reinstall the motor. Keep it at or below nameplate.

The last time I tried restricting the outlet it increased the amperage. I will try it again sometime. Maybe the OP can test his setup while he is at it.

lilredex · Jul 7, 2010

Torque1st said:
Make sure you check the current when you reinstall the motor. Keep it at or below nameplate.

The last time I tried restricting the outlet it increased the amperage. I will try it again sometime. Maybe the OP can test his setup while he is at it.

Are you referring to me? If so, I just happen to have a belt drive fan ready to go, with I think, a two speed 1/2 HP motor on in. I don't have an ammeter that will measure current that high, but I can measure the motor's temperature with my trusty thermometer...my hand. Maybe do it tomorrow if it cools down here a bit. Get back to you with my findings.

Torque1st · Jul 7, 2010

Nope, Bookman the OP. Post just above mine.

squirrel cage fan

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