OT - electric motor question

[whateg0]

Dad has an old attic fan that he took out of the house a few years ago when they had central air installed. He wants to use it in the shop to move "a little" air, but said he was having trouble getting it to run right. So, he sent it home with me to have a look at it. I, too, am not sure about this thing. I forgot to get a pic of the electrical connections when I was outside tonight, but I did remember to write down the motor's model number, and drew a diagram. Maybe somebody who has a ref for motors can look this up. The motor is a GE 5kh3qpa0358x. It's 110V, 1750 or 1000 RPM, 1/3 or 1/9 HP, I suppose depending on the speed chosen. When it was taken out of the house, it had two speeds, hi and lo. It also had a timer, but that's not relevant. When I picked it up, there were three wires coming out of the motor, that each went to a screw terminal.

I've attached a diagram of the connections. Now here's the issue. The motor turns backward. The fan should be pulling air in from the front, but instead rotates the wrong way. I suspect this could be as simple as switching the blue and brown wires which are on spade terminals, which I believe are the start winding, but I'm not positive. The three wires in place when I picked it up were attached to terminals 1, 4, and 2. All of the wires in the drawing are internal to the motor. (I removed all three white wires from the motor when I started to work on it.)

http://www.hobartwelders.com/weldtalk/attachment.php?attachmentid=29489&stc=1&d=1250058253

Any help is appreciated.

Dave

[vicegrip]

Dad has an old attic fan that he took out of the house a few years ago when they had central air installed. He wants to use it in the shop to move "a little" air, but said he was having trouble getting it to run right. ..............
............. Now here's the issue. The motor turns backward. The fan should be pulling air in from the front, but instead rotates the wrong way. I suspect this could be as simple as switching the blue and brown wires which are on spade terminals, which I believe are the start winding, but I'm not positive. The three wires in place when I picked it up were attached to terminals 1, 4, and 2. All of the wires in the drawing are internal to the motor. (I removed all three white wires from the motor when I started to work on it.)

http://www.hobartwelders.com/weldtalk/attachment.php?attachmentid=29489&stc=1&d=1250058253

Any help is appreciated.

Dave

The motor turns backward.
Not necessarilly Dave!
Backward? relative to the pitch of the blading?

These were not allways installed correctly.....blade may have been reversed.
Some are unaware that a blade pulls better one way then the other.

VG

[whateg0]

Phil,

The issue was that the blade was turning backward. You are correct that any non-symmetrical blade will work more effectively turning the right way. That's what was wrong here. The starter winding was wired backward, so it started the wrong direction. I switched the windings around and it works great. I never did get two speeds out of it though. Dad was happy it worked at all, so I left it at that.

Dave

[Thurman]

A couple of questions here: Was the fan mounted in the ceiling of maybe the hallway of the house, or actually in the attic? Is the unit belt driven or direct shaft driven? The reason I ask is that a lot of "whole house" or "attic" fans, whether belt driven or direct driven are made to run backwards. When you say the fan has two speeds this makes me feel that it is a whole house fan, and a lot of these had the speed selector mounted on the wall near the fan. This allows the motor to be above the fan blades when installed in a ceiling, or in towards the attic space if mounted in a gable application. Turning a fan blade around will not make air move the other way. As stated, fan blades are designed to move air efficiently in one direction. IF the above happens to be true in the case of your fan, then I am surprised that you got the motor to run in the opposite case, although it may IF the windings happen to be wound a certain way. BUT-I'm thinking that you will now burn out the motor, soon!