Wiring for a furnace blower motor

[BlueRidgeMark]

I tried to add this to another thread I started, but for some reason I cannot reply to my first post, and can't edit either.  Weird.

 

Anyway, I'm trying to use this blower to move warm air from my woodstove to the other end of the house (via ducts).   I know my way around elecricity, but I have no experience with motors.  Here's what I think I know about it:

 

2. I'm assuming this is a 3 speed motor, or perhaps 4?  
3. 
   
4. I want to take advantage of the multiple speed, so I'll need a multiposition switch.
5. 
   
6. The transformer is probably used to power the original HVAC thermostat system, so not needed for my application.
7. 
   
8. The capacitor is needed for starting.
9. 
   

 

Good so far?  Or do I need some course corrections?

 

Most importantly, what wire does what?  What can I toss, and what do I keep?

 

Thanks!

 

 

 

 

 

 

 

 

 

 

 

[m_west5]

Transformer not needed. Power source is 115VAC. Hot, neutral, ground, and speeds are dependent on how that particular motor is wired. Check the part number and manufacturer and google it for the technical data, if possible.

And you will need to fuse the circuit properly or install a circuit breaker for this fan (by amperage). This MUST be done or you will have a fire hazard. Do not use without a circuit protection device. It should be on its own circuit with nothing else on it.

RUN cap needed. Looks old, but if you have a capacitance tester, it would be a good idea to test it. (Microfarad).

Looks like a 3 speed. Can you get your eyeballs on the motor spec sticker or is beneath the mounting belly-band? It may have the simple wiring schematic on it, most do. Then wire it to a 3 speed switch. An evaporative cooler switch (swamp cooler) should work fine as long as the amps and voltage rating are correct. And make sure you ground the fan motor properly and to NEC specs.

How are you going to secure it in the vent system? These vibrate a good amount.

This is general motor information. Each motor is different, so you need to do the research.

[alamo1718]

First suggestion. Pull the motor.  There is a wiring diagram on the side of the motor. Unscrew the set screw on the other side, use an adjustable wrench to hold the shaft and rotate the squirrel cage to loosen the fan blades. Then loosen the band clamp and persuade the motor out.  You might have to unscrew the three mounts and pull the motor and band clamp out together. 

-If I am seeing correctly, the short wires that are connected to each other make the motor reversible. Orange and purple, I don't know what the wire nuts are covering. 

- It needs a functioning capacitor to start and run. 

-The transformer is not needed to run the motor.

-This looks like a 240 volt motor. Usually, one leg will always be connected and the motor speed will be determined by which other wire is powered. 

_ Please be dry careful. The squirrel cage turns fast enough to cut off fingers. If this isn't grounded properly and the motor shorts, the entire metal shell can become electrically hot and will hurt very bad or make you dead. 

-This slowest of these motors I have ever seen is 875 RPM. If is not secured when you power it, the entire assembly will probably spin like a top. 

- I saw radio loco's reply just before I posted. I might be wrong, but it looks like a 240Volt to me. The tag on the side of the motor will tell you. 

 

Just FYI. Home depot sells in line duct booster fans,6 inch, for under $40. I suspect this motor was free but it might be opening a can of worms. 

[BlueRidgeMark]

Thanks, folks!   Sorry to be so long getting back - there was a glitch with the forum and I could not reply to posts.  The Boss fixed it.

 

 

Thanks to your tips I found the data plate.   They had it well buried.   Odd, the data plate didn't mention the voltage.  I looked it up online using the model number.  It's a 1/2 horse GE.  115 volt, three speed.  I've tested it and it works fine on all three speeds.  That thing blows some serious air!

 

Ducts are mostly in and I plan to finish it up tomorrow.  I've built a box to house the blower and attach the ducts.  It will be fastened to the ceiling joists.   

 

Still need to run power.  That's the easy part.   The panel is in the unfinished basement, so I'll bring a new circuit over, up into the wall to my switch, then up to the attic.    And yes, I know about breakers, etc.   The shell has a ground wire, and I'll be using it.  Wiring is no place for shortcuts.

 

Thanks again! 

[BlueRidgeMark]

Well, it's in, working fine, and moving plenty of air.  How much hot air is hard to say at this point, because it's been a warmish day anyway, and we had the fire dialed way down. 

 

I plan to get a few thermometers placed around the house and do some controlled tests to see how much it's actually helping.  Should be interesting....

[m_west5]

I believe on high speed that fan will move around 400 cfm of air. And you should consider the integrity and insulation factor of your vent system, insulation factor of your exterior walls and roof, and the number of stories of your home.

Did you run the ground wire from the fan motor case to the basement service panel? This motor pulls a large amount of current at start-up.

Good job and thanks for keeping us posted.

Edited January 26, 2015 by Radio Loco

[BlueRidgeMark]

The vent system is new, installed for this purpose.  Right now, I just have elbows poked through the ceieling.  Now that I know it really does move warm air, I'm going to get some proper filtered registers for the intake, and a diffuser for the output in the living room. 

 

 

Yes, I grounded the case all the way back to the panel.  I ran a new circuit for it.  Currently, I have it run thrrough an ordinary light switch becaxue I forgot to source a 3 speed switch for it.  I just connected the middle speed lead through the light switch for now.

 

Found a good one online today, so I'll replace the light switch probably this weekend.

 

[alamo1718]

Reference the switch. It has to be one that "shifts' the voltage between wires. Said another way, the motor always gets 120V, it just changes speed depending on which wire feeds power. Some variable speed switches vary the voltage. If you use one of these and vary the voltage, the motor will burn out from under voltage. 

 

Sounds like a cool project. (sorry about the horrible pun) 

[BlueRidgeMark]

Yep.  Like I said, I'm familiar with electricity, just no experience with motors.  I know the theory, just not industry practices.

 

I'm looking for one like this, but I don't like going from "Off" to "High".  I'd rather start with Off then Low, Med, High, but nobody seems to make them that way.

[alamo1718]

I've never seen that switch before. However, you might be able to hook the low speed wire from the motor to the high speed terminal on the switch and the low speed wire from the motor to the high speed terminal on the new switch. 

 

Maybe some one else can comment, it's just a thought. 

[BlueRidgeMark]

Yeah, I  thought of that.  It's all the same inside, so it would work fine, but I don't like having a label that is backwards.

 

 

Now that we've had it running a few days, we're getting used to the living room being warmer than down by the stove.  I was pretty sure this would help, but I had no idea how well it would work!

 

And I haven't even insulated the intake and output elbows yet! 

[applianceman18007260692]

You can get a fan Klixon with 3 poles that allows for low speed to start then when the temp gets up there it kicks in to high or vice versa. They make em for williams wall heaters with 2 speed motors. The motor you have there is a capacitor driven 3 speed black high, blue medium, and red low. If you should tie any of them speeds together the motor will be destroyed. Most heaters use red and white to 120 volts. Heaters run on slow speeds while high speed is used for AC. The blower must also be mounted inside a duct so that proper static pressure can bring it up to full speed or else it will get hot and quit.

Edited January 28, 2015 by Dan Webster

[BlueRidgeMark]

No need for automatic controls.  Right now, it's wired for medium, and it's doing just fine.  I don't think we'd want to run it on high.   It would be too windy.

 

I think I'll just keep looking until I find a switch that works the way I want it to, or doesn't have the positions labeled. That way I can wire it the way I want it.

 

For the summer, I want to interrupt the supply duct with a diverter that can be controlled by a switch downstairs.  Let it blow into the attic and act as a whole-house fan.

 

That's for later. 

 

For now, the next step is to get a diffuser on the outlet and a couple of filtered grills on the intake.  Using the two intakes has worked out well to keep the wind noise to a minimum.  It's really quiet at that end.   I'll oversize the grills for the same reason.