Changed Motor and installed Fanhandler; now have annoying noise at slow speed.

[stanhvac1]

Couple of questions. What are you calling a fanhandler? Why is the motor running on slow speed when the heat is off? Did you replace the motor and why?

[homeowners]

Fanhandler as in

? I'd say what you hear is a result of vibration that you would always hear, except that the Fanhandler controller now lowers the speed when heat is not on and so what was too high a frequency to hear before is now audible. Is this a squirrel cage type blower? Did you clean the rotor before putting it back on the new motor? 

Also, not to get too technical about this but the chirping sound that (larger) helicopters make is a result of the blades changing airspeed on each rotation from going faster than the frame on the way forward to slower on the way back (and flapping and turning in the process) - nothing like that can happen in principal with rigid blades of a stationary blower, so it's definitely not air making the sound - it's got to be mechanical.  Something rubs against something. Did you tighten all bolts holding the motor carefully?  A combination of a loose bolt with an unbalanced rotor (due to dirt, dust and hair that tends to accumulate on it) may create a sound like you describe. It would be pretty bad and would need to be fixed ASAP lest the new motor's bearings get ruined, too.

[stanhvac1]

Thanks for the input on this. I was not aware of fanhandler. Thanks for the link. I glanced at it and I will study it throughly. It's getting hard to keep up with all the new technology on the market.

[Dan]

The noise is like a high-pitched helicopter and it's heard from the motor area. Slightly reduced if air filter removed (which is just in front of motor area). What could this noise be? It goes away when motor runs at heating speed.

Thanks, Dan

[homeowners]

 I am always glad to help, Stan! Let's just hope that this is what the original poster actually had in mind. By the way, the manufacturer makes a few claims there that are really hard to verify, and I find it a bit ironic given Dan's experience that one of the benefits touted is "quiet comfort". I mean, it's hard to compare a slower running fan to a stopped fan and still call it quieter, regardless of any unusual mechanical noises it makes. 

I also need some time to wrap my head around the idea that running a PSC motor at half speed uses only 1/8th of power used at full speed. Perhaps I'm just too slow tonight from all the snow shoveling :)

Yet another idea I just can't be completely sold on is that if you keep the air circulating in the ductwork, it is more efficient than if you stop it and let the air that's in the ductwork cool, then spend energy on heating it up again.  You would think that there's quite a bit of extra cooling going on in the ducts that are insulated less than the room (not the least because the air was supposed to spend little time in them). This would be quite unlike advocating keeping the ceiling fans on in winter because the ceiling fans just move the air inside the well-insulated room and no extra cooling occurs.

Anyhow, didn't want to just jump in and start dissing the technology that may have merits in a particular situation, just seems like it needs some consideration before putting it in.

Cheers!

[yahoo-IXMSU4QYSTSOIAFMF7FOKYMAXE]

Yes, it's the Fanhandler as referenced above.  This is the second one I've installed and I love them.  They are an inexpensive little device that solves a big problem for me: running an HRV with a basic furnace--not variable speed--so that the air is always circulating, at lower speed (instead of high / one speed); otherwise the HRV, being fed into the return duct, would obviously blow out unfiltered duct air back into the room when furnace would otherwise be stopped.

My only comment about the literature on their website is the idea that a motor running continuous is better than one "banging on and off" for years; but of course, every time the thermostat calls for heat, the furnace stops the fan to heat up the burners/heat exchanger then turns the fan on again, fanhandler or no.

In my first install at my previous home, I had no noise issue.  The fanhandler also responds to sensors placed in the supply duct and I would say yes, it is overall quieter, as you don't seem to notice the heat speed so much.  My only concern is a lower heat rise, which I have yet to measure.This time around, I changed the motor as the old motor in this furnace was making funny noises.  Fanhandler supplies, at what appear to be cost, a high quality Baldor motor.  Except I can't figure out the noise i've described.  I turned up the minimum speed a bit and the noise is gone, but now I have a bit of a draft.The return duct in this installation seems wrong--there is an empty electronic cleaner box between the furnace and the return plenum but it was installed so that the original 16" wide return opening on the furnace had to be shortened to 14".  I think I need to do static pressure measurements but I don't have a manometer and can't find one to rent.So, now it is quiet but running a bit fast on "circulating" speed.Thanks,Dan

[yahoo-IXMSU4QYSTSOIAFMF7FOKYMAXE]

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