Balanced fan = quieter stove

My dealer gave me a new fan and motor to replace the noisy combustion fan in my Afton Bay. I'm thinking this is some aftermarket thing, since it doesn't have the St Croix part number on it, and lacks the isolation bushings that seem to be OEM. I bench tested the new one, and it vibrated as badly as the old one. Having nothing to lose, I decided to see if I could balance the fan by removing some metal from the heavy side.
It seems to have worked. There is negligible vibration now on the bench, so I expect it will run smoothly in the stove.
I used my trusty Dremel and a milling bit to chew at the fan base:





It does have a Fasco motor, sealed bearings. Now that I have the old one quieted down, I'll just wait to install this one - although my curiosity may overcome my inertia and force me to put this one in the stove to see what happens.

Nice job......I'll be interested to see the difference when you finally put the new one in.

Thanks! I'll update when it happens.

Did you remove the fan to check the balance? I have a magnetic wall mounted blade balancer that might work for just this.
I love the ingenuity that I read about here, it just makes you think...Why the hell didn't the OEM think of this?
Now, I want to order spare blower assemblies to balance and see how quiet I can get my stove.

Bill

I had a similar experience with the convection blower. I used a zip-tie to add weight to the light end of the squirrel cage.

http://www.hearth.com/econtent/index.php/forums/viewthread/86900/

They didn't think of it because they rather make things in China and make money. :-S

hm....not at all uncommon to see balanced fans these days......check out a harman distribution fan sometime, particularly in the P series units. Very common to see a weight clamped to the fan.....

Sounds like a great idea, Could you explain in detail the method you used to check the balance?
Thanks

I didn't remove the fan, although I could have, and used a lawn mower blade balancer - but I didn't think of that in time, and I wanted more immediate feedback to see if it made any difference. I ran the blower every so often to check for improvement in the vibration, and the results were encouraging, so I continued. This was as much for a fun little project as for improving my stove's performance.

Gio -

I held the unit so that the blade assembly was in a vertical plane. In an ideal world, the heavy side would just have ended up at the low point. To overcome the bearing friction, I turned the motor itself back and forth an inch or two. That kept the bearings moving and negated most of the "stiction" in them, so the blade was freer to turn. I put the blades in various positions to start, and the same spot kept ending up at the bottom, so I was convinced I was on the right track. The Dremel couldn't quite reach where I wanted to remove metal due to the blades themselves, but I got close enough. That explains the uneven metal removal. It was trial and error, take a little off, try it, take a little more off. I eventually got to the point where the same spot on the fan didn't always go to the low side. I quit at that point, and the improvement in vibration was very evident.
The whole process took maybe ½ hour. I would assume (yeah, dangerous, I know) that the bearings might last longer without the imbalance, but heat and other factors may be more important factors in bearing life.

I did a similar process with my cage fan. I just used a zip-tie to add weight to the light side of the wheel. Here's what it looks like.

Excellent idea! My room blower seems to be original, and seems well balanced. I don't know if it has weights or not, didn't think to look when I cleaned it last spring. I do know the two squirrel cages are longer with a smaller diameter, so maybe a little out-of-balance doesn't matter so much.

The convection fan on my 10-cpm has a balance weight, and my '05 Astoria had one also. Never seen one on the comb. blowers, though.

I dont think theres much point in trying to balance that fan because its just going to get caked with soot and ash anyway?

Hopefully it would be a nice even coating, and the ash probably has next to no weight. Just a WAG on my part.

Yes, but as Heat Seeker mentions, the coating will be even on all the vanes. If one side is too heavy while it's clean, it STILL will be out of balance with the soot.