Rebuilding blower fans...

[73blazer]

So I've had issues with the fans in my Heat n. Glo North Star unit (in other forms, Heatilator Constitution or Quad 7100 and I believe they fit many other models of hearth&home fans, and most other units will be extremely similar anyway). They start making some eery noises, but mostly they just start getting loud. It's just the bearings in them, I'm going to surmise.

I had 2 sets of these fan units replaced while it was still under warranty, but now it's out of warranty and they want upwards of $175 which is what you have to buy, the entire fan assembly complete with motor, bearings, housings/squirrel cages etc.

One set was getting loud towards the end of last year, I turned it on just now, yep, it's a noise maker. The fans are kinda a low background noise, while I'd rather not have it, they are necessary for this unit to heat the house, but if they're working right, you mostly don't notice it. But when they start acting up, it's a downright annoyance.

So, I took one apart and will order some new bearings for them. These have 608 metric bearings in them.
8mm Shaft, 22mmO.D and 7mm thick.

The fans come apart fairly easily, small pinch clamp holds the squirrel cages onto the shaft, remove clamp, pry up on cage from bottom and it comes off. 4 small hex screws hold the metal housing onto the motor brackets, and then 2 long hex screws hold the motor brackets onto the motor. Once the motor brackets are off, you can slide the motor axle out with the 2 bearings and the motor rotor. Then simply pull the bearings off the shaft. I have a bearing puller, but they're not on the shaft all that tight, but you'll need to pull the bearings off.

So I ordered some replacement bearings from McMaster-Carr. The ones on the unit are double-sealed, so I ordered those. You can get in either steel ($5) or stainless steel ($13). I suspect due to the harsh environment in which these live, lots of small fly ash, heat....it's the reason they fail fairly quickly. If these new ones fail quickly, I may just try shielded or even open and just clean and lube them periodically. Mabey..we'll see.

Anyone replace these bearings before? Figured I'd try it before I spent $350 on new fans.

 

[Anumber1]

Thanks for the disection.

I love to rebuild stuff instead of replace in kind with the same equipment, especially if the original equipment under performed.

Good luck with the rebuild!

 

[blades]

See if they have bearing rated for high heat. That is generally the culprit as the lube dries out. Re-lubing helps some but generally the little balls have flat spots by then which is what causes the noise (need high magnification to see this) Years back worked on machines that the bearings were subjected to 169 deg C 8-10 hours a day - constantly replacing the OEM s- dug around for some thing better which I found and we could get a couple years out of those vs the couple months of the oem units.

 

[73blazer]

I looked a around quite a bit. The only ones I could find that places stocked were regular steel in two grades , or stainless (type 440) . All had buna-n seals. Buna-N is Supposedly good to 250F. I was hoping to find one with a higher heat rated seal. But I've IR'd that area down there before, it really never gets much above 140 or so. I'm hoping the harder stainless balls will last longer. The only other choice I could find is a full ceramic bearing, but they want $45/piece for those. Would be interesting to try.

THere were some other options, different seals, pick your material, but it was all custom order stuff, aka had to order min. quantities, usually in the 100's.

I popped the seals off of one of these. You can see particles of flyash in the lube. So, it's the seals that are letting them down. Mabey I ought to make a habit of shutting off the fans while I re-load

 

[velvetfoot]

Good work!
I poked around looking for an ECM motor to replace the existing one. I figure the fan is on almost all the time.

 

[Anumber1]

I looked a around quite a bit. The only ones I could find that places stocked were regular steel in two grades , or stainless (type 440) . All had buna-n seals. Buna-N is Supposedly good to 250F. I was hoping to find one with a higher heat rated seal. But I've IR'd that area down there before, it really never gets much above 140 or so. I'm hoping the harder stainless balls will last longer. The only other choice I could find is a full ceramic bearing, but they want $45/piece for those. Would be interesting to try.

THere were some other options, different seals, pick your material, but it was all custom order stuff, aka had to order min. quantities, usually in the 100's.

I popped the seals off of one of these. You can see particles of flyash in the lube. So, it's the seals that are letting them down. Mabey I ought to make a habit of shutting off the fans while I re-load

I doubt the armature of that motor is good for more than 80c or 250f degrees either. I bet those stainless bearings would last a while.

 

[kd460]

I have replaced the bearings in mine...it is a common bearing used in vacuum cleaners, electric motors, and skateboard wheels. Yep, a skateboard shop will have the 608 bearing and in a pinch (like on a weekend when the bearing starts to make noise).

Check online sources and even fleabay. They have exotic bearings like ceramic if you want to give that a try. KD

 

[mminor]

Hello. I will be purchasing the Heat and Glo Northstar fireplace as well, so this is very helpful to me. Thanks for everyone's information!

Would you guys recommend replacing the entire two fan units prior to installing the Northstar into the wall (bump-out configuration)? In other words getting higher grade / industrial grade fans to replace the crappy Northstar fans from the start? I imagine there are better fireplace fans (quieter, more reliable, better built, etc) on the market - can you recommend any brands / models that will work with the Northstar?

Thanks again for everyone's advice!

Matt

 

[73blazer]

Hello. I will be purchasing the Heat and Glo Northstar fireplace as well, so this is very helpful to me. Thanks for everyone's information!

Would you guys recommend replacing the entire two fan units prior to installing the Northstar into the wall (bump-out configuration)? In other words getting higher grade / industrial grade fans to replace the crappy Northstar fans from the start? I imagine there are better fireplace fans (quieter, more reliable, better built, etc) on the market - can you recommend any brands / models that will work with the Northstar?

Thanks again for everyone's advice!

Matt

The fan size and configuration and how they mount are kinda model specific, although at a glance most fireplace and stove fans appear very similar. I wouldn't go out of my way to replace them before you install, it's not any easier, still have to go in thru the access plate in the floor of the firebox. Plus the last fan set that was replaced was replaced with a completely different model of fan motor, and has been in over three years now, so I'm hoping mabey the different manufacturer used better bearings? Hard to say, if your unit is newer, you likely have these newer fans anyway.
I'd leave your fans and use them happily. If they start making high pitch erry noises 2-3-4 years from now, you'll know what to do (warranty!). if they start making noise more than 5 years from now...you'll know what to do as well, replace these bearings!
As a heater, the north star is awesome! Use dry wood though

 

[mminor]

Hi Blazer.

Thanks so much for your detailed response and advice for me before my Northstar gets installed - it's super helpful. I will certainly save this thread for when I need to replace my ball bearings!

I did some general reading on the 608's and people seem to like the ceramic bearings and claim the extra cost is worth it. And I think the stainless steel option has to be better than what the fan originally came with. But like you and others said - it probably has more to do with the high heat sealant than anything else.

Can you please let us know what you ultimately purchase and how it works - this has been really useful!

Thanks again.
Matt

 

[73blazer]

I ordered 4 of the stainless bearings, they arrived and I rebuilt the noisy set, and a set I had on the shelf that was warrantied a while back (they never asked for the old ones back). The bearings in that set were trashed!
They are quiet again! Hope they last! I think the hardest part of the job is getting the blower wheels off shaft, you can't really get under them to pry them off and they're kinda flimsy so you can't put much pressure on them. But...I soaked the shafts and let 'em sit for an hour then just worked them a mm at a time off.
And now I have a spare set all ready to go if one acts up again.

 

[bruce_m]

I've had my HnGlo Northstar installed for 8 years, this is the 8th heating season. We use it continuously to heat our home. 2 years ago both fans started making noise. I ordered one fan (@170.00 IIRC) and put some gun oil on the rod/bearings of the other. seemed to fix the issue at the time although the new HnGlo fan was just noisier overall.

Last year the fans worked quietly and before I started this heating season, I thoroughly cleaned dusted vacuumed the fans, and made sure to oil the rod/bearings of each fan with gun oil.... (i suspect any light oil like sewing machine oil etc would work). The fans were quiet for a month or so.

Now, after they have been off for a while... day or so.. there is a squeal that comes from the fans... (suspect its just ONE fan) but its not bad enough to tear out and investigate because after 3-4 minutes the fans get quiet... I suspect there is just some ash dust that works its way out.

Because the fans are under the fire box where the fresh comes in, I don't think they get that hot overall. It is frustrating though when they get noisy.

Thanks for the posting and pictures of the rebuild... I hadn't figured out how to get the fans apart to replace bearings etc..

 

[rustynut]

hi 73,....I had a blower on my Dutchwest that got loud as well. It ran fine so what i was able to do was build a couple of oil ports out of very small copper tubing from a hobby shop. This allowed me to oil those squeeky bearings when ever they needed it. Just a little dab l do ya !.....haha. It worked great. Once or twice a season and you would know when its time. I used a metal cap off a pencil to cover the tubing. It was easier than tracking down the bearings and changing them. I used an eyedropper to apply the oil into the tubes. Never did have a bearing failure. Have a look......... RN

 

[blades]

If you can find this item "RIG" It is a firearm preservative. It was off the market awhile. Its back now works real well with those permanent lubricated bronze bushings ( that always dry out just after warranty) as well as ball bearings -What I have is the orginal stuff- I do not know if the formulation from Birchwood Casey is the same though.