Help with blower motor identification

I have an old Lennox furnace. By ‘old,’ I mean that it will turn 40 later this year. (I can dimly remember when I turned 40.)

The blower motor seems to be failing, for lack of lubrication. It’s been making inappropriate noises that I believe are indicative of bearing failure. The motor is direct-coupled to a large ‘squirrel cage.’ Much of the motor is actually inside the squirrel cage.

My first goal is to keep this rascal running until the end of the heating season. (I live in southern Wisconsin.)

Lubricating one bearing was easy. I was able to pull a MacGyver that involved small diameter tygon tubing and a fair amount of blood, and I finally got some oil into the inner bearing. The noise seems worse.

My second goal is to replace the motor, at my leisure -- like maybe in June. I have figured out how to R&R the motor. If at all possible, I don’t want to tear into it before the outside temperature gets high enough that I can live without it for a couple of weeks. I know a lot about things that can go wrong with a project like pulling that whole blower assembly and trying to get it apart, and trying to get a new motor into it.

My hope is to buy a new motor and have it on hand, in case the motor seizes or shows signs of imminent catastrophic failure. I think that’s unlikely, but I know that Murphy was an optimist.

My problem is identifying the motor. There’s no way that I can read the nameplate (assuming that it HAS a nameplate) without a major teardown.

Here’s what I think I know about the motor:

¾ hp
110 vac
OAO
5 speed (only 2 used, as far as I know)
direct drive
clockwise rotation

I don’t know the shaft length or diameter.

I’m pretty sure that it’s some flavor of 48 frame. I believe the style is ‘hub mount.’

The furnace is a Lennox G12Q5-165

Is there a fantastic reference somewhere that will point me to the right motor? I’ve had some success in the past with Johnstone Supply; will an outfit like that be able to provide the right motor? I don’t really care who makes the motor; I do care that it not cost a fortune. My concern with buying from Grainger or Johnstone or anybody else, on their recommendation, is that it won't be a PERFECT match. If I could get the 'right' motor -- a perfect drop-in -- I'd really like that!

With gratitude in advance for any advice you can share,

Paul in East Troy

 

Welcome to the forums.

Maybe your second goal should be looking into a new furnace.
With the age of that unit you need to start considering that the heat exchanger may be rusted thru. Another plus would be cost savings on higher efficiency.

So far I've found the prices all over the place.... not sure why.

Midwest HVAC Parts. Blower Motor 28F01

32820 -- P-8-8326 3/4 HP BLOWER MOTOR 1075 RPM 115 VOLT 60 HERTZ 1 PHASE

3/4 H.P. 115 Volt Furnace Blower Motor (5/8quot; Shaft) LENNOX | AmericanHVACParts.com

 

Thanks for your response, PJmax. The best price (and fit) that I've come up with is the same as what you found, at Midwest HVAC Parts. Well, actually, I think I saw one for a few dollars less on Amazon... I think that the highest I saw was 50 bucks either side of $800.

I'm curious about where you got the specs that you posted. I'm confused, because I don't see any mention of the shaft diameter on that website. I'm going to have to get in there with a mirror, a tape, and a light; I thought that the motor had a 1/2 inch shaft, but you mention 5/8.

I certainly expected someone to suggest a new furnace. (And if I were going to have to spend $800 on a 3/4 horse motor, that might put me over the edge!) I'll certainly be looking into that. The heat exchanger seems ok, although only as determined by a lack of CO in the output. I was nearly astounded by a local HVAC / plumbing / well guy -- someone I trust, and who is even older than me -- who told me a few years ago, when I was considering a peremptory replacement, "Why would you replace a furnace that's working perfectly well?" And I get it, that it's time to be thinking that this machine's days are numbered.

Thank you again.

Paul

 

The 28F01 is a 1/2" diameter shaft. This is most likely the correct motor for your furnace.

I don't think the other ones I listed are for your furnace. The price is way too high. May be a variable speed type motor. It also shows as a 5/8" shaft which seems unlikely for your furnace.

When you pull the old one out it should also have a part number on it that can be cross referenced.

 

Thank you for the followup, PJmax.

I have ordered the 28F01, and I have faith that 1) it will fit, and 2) that if it doesn't fit, they will take it back. [I just checked -- they have a 25% restocking fee. Evil.]

You mentioned that I'll probably find a number when I pull the motor. But I want to have the motor on hand BEFORE I tear into it. Removing the motor is no mean feat. The wiring of this furnace has obviously been worked on a few times, by guys who wanted to getting it running the fastest possible way -- probably with the parts that were in the van. The phrase 'cobbled together' comes to mind... Anyway, all that interesting wiring has to be physically moved to get the blower assembly out. Then, once the entire blower assembly is out, comes the challenge of getting the squirrel cage off the shaft. So I don't want to do this more than once -- and I need the furnace to be 'down' for as short a time as possible. (Over the next few days, temperatures here will range from 19 to -16.)

Trying to confirm the shaft size was interesting. Looking at it, with a mirror and flashlight, I say that it's 1/2 inch. But, using a crescent wrench for a caliper, I get 5/8. (There's no room to get an actual caliper onto the short -- I don't own a stubby caliper.)

The existing motor has a flat on the shaft. I suspect that the 28F01 does not (but I don't know how to confirm that before it gets here.) I wonder if I can get the squirrel cage tight enough to not slip...

The motor won't be here for a couple of days. In the meantime, I'm thinking about trying to loosen the setscrew on the squirrel cage. It's a square head, probably 1/4 inch. I'm hoping that I won't need a puller to get the squirrel cage off the shaft. Any opinion on that?? In fact, I don't know how I could get a puller in there. A ball joint separator comes to mind -- the old, simple wedge type -- but there's no way to get that in, either. I can't imagine trying to drill it out.

Thank you again for the gift of your support!

Paul
(What part of Jersey are you in? I lived in Landing for 10 years.)

 

I have the new motor, I have the new cap, and tomorrow is the big day, when I pull the blower and replace the motor. I have tried to move the squirrel cage on the shaft, by banging it from the motor side (with the wooden handle of my favorite ball peen hammer), while rotating it by hand. No joy, so I figured I'd better get a puller. (The setscrew came out of the hub so easily that I thought maybe the squirrel cage would just jump off the shaft. No such luck. 40 years is a long time for a hub to be on a shaft.) So my wife drove into Milwaukee this morning and got me a UP-1. And now I'm wondering if it will work. She measured the puller, and it has an ID of 1-3/4. Any thoughts about whether the hub on that blower (3/4 hp, 1/2 inch shaft, 165 kbtu unit) might be bigger than 1-5/8? It's not so easy to measure with it all still in place. I have this ugly vision of running the blower and reaching inside with some sort of abrasive to take a few thousandths off of the hub. Sounds like a good way to end up with a bloody stump dangling from a broken wrist. Have I bought a $60 tool for naught, or is going to work perfectly?

I'm supposed to swap the motor out tomorrow, but I may not be able to wait, and jump on it tonight. If it goes well, I can put the water softener back together tomorrow!

Thanks for any insights,

Paul in East Troy

 

Heat it up with a torch, it should just fall out.

 

Heating it is a good idea.

Sanding off the shaft is useless. You need PB Blaster, Liquid Wrench or some type of rust remover to shoot in the hub and setscrew hole.

What's holding the blower to the shaft is the burr that the setscrew puts in the shaft. If there is room between the blower and the motor..... you can use a piece of pipe just larger than the motor shaft to tap the blower down to loosen it. Sometimes it will slide down far enough to enable you to file the burr off.

 

The Sensible Products UP-1 'Ultimate Puller,' sold by Johnstone supply as H85-404, is too small for my hub. I am SO disappointed.

The next step is to get the whole thing apart as quickly as possible. It's almost 7:00 AM; there's a place in Milwaukee that's open until noon. If I need a puller, maybe they'll have one that's big enough. Or maybe it's going to come apart easily.

I'm not at all convince that the issue is a burr on the shaft from the setscrew. The motor has a flat on the shaft, and the bore of the hub is round. The setscrew meets the shaft on the flat. So I don't think it can be a burr -- there's way too much clearance for a burr to cause any trouble. And, so far, the cage has not moved on the shaft at all. I would think that, with a burr, there'd be SOME movement -- a little bit of twist, a small jog of the shaft...

The idea of driving the hub farther onto the shaft is intriguing. Once it has moved, broken loose, it should come off. Well, that's the theory. And heating the hub might work, either by expanding the rub or just breaking the 'seal' between the two parts. I'm partial to using two torches on opposite sides, to heat the rub as fast as possible while the shaft temperature lags behind.

You know, you guys are really helping. Just having somebody say, 'Aw, you can do it, just dive in" is really supportive. Forums like this, where people are willing to share their experience with rubes like me, are a great gift. 'Virtually community' is a good thing!

Thank you,

Paul

 

I thought that it was bad that the puller doesn't fit the hub. That's not so bad, now that I've gotten in deeper.

The motor I bought, the one that's recommended, is 2-1/2 inches shorter than the original. It's a 'hub mount' motor -- the motor bracket supports the motor with clamps at each end. So the bracket is 2-1/2 inches too long.

I'm trying to think creatively about how to piece this together. One thought is to put it all back together (I was VERY careful to not destroy anything taking it apart), return to motor to MidwestHVAC (who will keep $61.25 for their trouble), and walking into Johnstone Supply on Monday morning with the old motor and saying, "gimme one of these." Other ideas involve a plasma cutter and a welder, and I'd rather not. The geometry of the bracket is such that it would not be trivial to shorten it, I think.

And, of course, the cage is still on the shaft. And if I go for another motor, it means putting it back together now (4 degrees tonight, -7 tomorrow night), and then taking it apart again Monday morning.

Seems like it's never easy.

Frustrated,

Paul in East Troy

 

The setscrew doesn't only put a burr in the shaft it slightly egg shapes the shaft. In your case it's probably more due to rust.

Things don't always go as they should.... been there done that.

You should be able to see the motor number now.

 

Would it be possible for you to post some clear pictures of the old motor in the bracket, the new motor, and the bracket? Would like to see what you are seeing.

 

My guess is he's working with a motor like this.

 

I can't post any photos of the old motor -- it's back in and running.

The photo that you posted, PJmax, is very similar to what I bought from Midwest HVAC. The actual mount in the furnace is quite different, but the type of clamping mount is the same.

There is almost no similarity in the motors. The one I bought is a 48Y frame with a 1/2 inch shaft. The one in the furnace is a 56Z frame, with a 5/8 shaft. Feeling pretty stupid right about now...

Getting the cage off of the shaft wasn't too bad. Penetrating oil and maple blocks. Once we got it apart, I cleaned up the shaft so that it would go back together easily. I also figure out why I couldn't see a nameplate on the motor: it was behind one leg of of the mount.

The motor is a GE 5KCP43SG1008S. I haven't shopped for it yet, but I did see one: $681 and change.

As depressing as it is, things went pretty smoothly. The shaft is cleaned up, and it will come apart easier next time. The motor is lubed, and seems to have enjoyed the TLC -- it's running quietly, for the moment.

My wife is trying to convince me to run it this way for 3 weeks. That would be an interesting crap shoot. We've got out-of-town company coming for a couple of weeks, and a lot of other stuff going on. If I can get my hands on the motor and cap, I might be willing to risk it -- I should now be able to swap it out in 2-3 hours.

Thank you for all of your help! I feel as though I've wasted your time. But I know a lot more now, and I'm well positioned to make the 'real' repair when I find the motor. And, if the motor is really going to cost $600-$700, I'm going to have to seriously consider a new furnace.

Thanks again,

Paul
"I'll be back."

 

I agree Ron53. Pics would help. One time I'm thinking belt drive situation based on the mount, to direct drive because the motor shaft is stuck on the blower wheel.

 

As I said, the motor is a GE 5KCP49SG1008S. It seems as though nobody knows that exact number except GE. But there's another number on the nameplate: P-8-8326. I get more hits on that, and it crosses to Lennox 32820. Those numbers lead me to Fasco D2861. Searching for all these numbers, I find prices from $221 to $1456. I'll have to wait until Monday morning to get Johnstone's price. If it's reasonable, I'll send my wife to get one. At the same time, she can try to get them to take back the too-small puller. Then she can go to Grainger and exchange the 40 mike capacitor for a 20. Then I can call Midwest HVAC and see if I can sweet talk them into waiving the 25% restocking fee.

This Fasco motor is actually a 1 horse instead of 3/4. I have no problem with that. It's a 3-speed, where the original was 5. I'll just have to decide between high and medium or high and low.

It was kind of a fun day, even though the project isn't done. Now all the required tools are in one place, the cage is broken free of the shaft, and I know what it takes to get it in and out. If I ever get the right motor, it should be a cinch to finish.

Thanks to all of you who walked with me as I stumbled through this one. I want you to know that when I can, I help people, and when I can, I teach them.

Paul in East Troy

 

No co output doesn't mean the heat exchanger is still good.

I really wouldn't spend a dime on something that old even if it's not leaking co:

1. It's only around 60% efficient on average. The pilot burns gas continuously and the draft hood continuously vents air you paid to heat up the chimney

2. It lacks the safety features of a modern furnace - blower compartment safety switch, rollout switches, sealed combustion, and more.

Replacing a blower motor on something that old is frankly a total waste, unless you don't have the funds for replacement.

 

Thanks, Muggle.

I think that it's a pretty safe bet that a new furnace -- furnace and a/c, I suppose -- is not far off. But it's winter, it's Wisconsin, the blower is failing NOW, and I don't want to buy a whole new unit without a lot of research and shopping.

Paul

 

You didn't waste our time. There are others reading and learning from this thread right now and more will in the future.


So your furnace did require the second motor I had listed. That's the expensive one. I didn't think they even used that type of motor 40 years ago. Hopefully the lubrication you used will get you thru the cold season.

 

I have to agree with Muggle that putting that kind of money into this old a furnace is sending good money down a rat hole.

The furnace in my home was about 17 years old when it started to light off with a bang. I determined it was due to the sheet-metal burners having lost quite a few of the "louvers" and then delayed ignition. After an extensive Internet search I found I could replace the burners for about $200 each or $600 for the set. That would have made it a $600 repair on a furnace that I could replace (myself) for around $750 or $800 with absolutely no guarantee that something else might not go bad the next week. It just didn't make economical sense.

So I cobbled up a temporary fix to get me through the next few months of cold weather and then had a new furnace installed. Yeah, it cost almost three grand for the new furnace but I got a whole lot of return for that money as well as a new furnace.

 

This story just won't quit!

PJmax, I was able to find a Fasco motor that should do the job for $245, at CSH Inc in Michigan. It's a Fasco D2816. The Lennox 32820 is obscenely expensive, but the Fasco is utterly reasonable.

Johnstone wouldn't sell me their motor. Probably I just got the wrong guy on the phone. I've purchased other motors there (e.g. condenser last year), and my wife just bought a useless Ultimate Puller there, but when I called this morning, the guy wouldn't talk to me unless I gave him an account number or business name.

I'm waiting to see whether Midwest HVAC is going to hit me for a restocking charge (25%). I guess I won't bother to complain, but $62.50 seems steep.

Furd, I think I'm doing the same thing you did -- cobbling together something that will get me through the season. Unfortunately, its ending up costing over $300. But some things just can't be fixed with bubble gum and bailing wire.

In the late 70's I pulled an old oil-fired 'gravity furnace' out of my house in New Jersey, and installed hydronic -- 3 or 4 zones, as I recall. That was fun! But I was 40 years younger. I wish I could do it where I am now, but the house I'm in doesn't lend itself hot water -- at least, not by an amateur.

Well, since I won't have the motor until Wednesday, I guess I can go to salsa class tonight! And I can stew for 48 hours about what I may have done wrong THIS time...

Paul in East Troy

 

I would have sworn I put a closing note in here...

The new Fasco motor is in. R&R was easy, taking just over two hours. The new motor runs quietly and smoothly.

Thanks for all the good information and encouragement!

I'm going to close out this thread and start a new one on blower motor speed.

Thanks for all your help!

Paul in East Troy

 

You already did that last week...... http://www.doityourself.com/forum/ga...tml?highlight=

 

As I recall I used baling wire and a tin can. No, I used sheet metal and bent it so it would snap on to the burner tube. It worked for the few months necessary but I never left the house with the thermostat turned up.

I was 49 when I bought this house and still in reasonable shape so working in the attic and crawlspace was fairly easy. I thought about going hydronic but it would have cost about three times what a furnace replacement was going to be. Now that I am pushing 64 (next June) the mere thought of going into either the crawlspace or the attic is enough to cause me to ache. It isn't so bad once I actually do it but the psyching up is the hard part. So much easier to sit at the computer and offer my advice.