Which Dayton (or other) small blowers are quietest?

[EddyKilowatt]

I am ready, mostly for the fun of it, to mess around a bit with a blower on my Avalon Pendelton freestanding stove. This stove has an insert-like design including air shrouding on 5 sides of the firebox. I am curious to see how much heat output increases with a blower -- contrasted with nuisance factors like noise and blowing dust. I guess I should admit up front that I have no problem with the heat output from the stove, I am just looking to tinker a bit... and who wouldn't mind getting a little more heat out of their wood, if it comes to that?

Anyway, one can buy small centrifugal blowers all day long at places like this:

http://www.drillspot.com/category/958/Small_Centrifugal_Blowers

and of course at surplus places and on fleaBay you can find similar stuff for a half the cost. Shouldn't be hard to find something that will bolt up to the air inlet port on my Pendleton. But the manufacturers (Dayton at least) don't seem to have heard of the dBA or anything else related to noise output.

Question is, which blowers are the quiet ones? Silence is one of my very favorite features of wood heat, and I don't want to hear more than a whisper from a blower if I do use one. The substation-like hum from my father's Buck Stove insert blower is completely out of the question.

I am thinking that slow speed (like 1500-1800 rpm) is better than high speed (3000-4000 rpm), and that a big blower slowed down and working lazily will be quieter than a small one spinning furiously. A 12 VDC motor would be easier to slow down (I can handle the power supply), plus wouldn't be humming at 60 or 120 Hz like a shaded-pole motor.

So, does anyone have experience with blower noise and/or advice on silently pumping air through a woodstove or insert? I am thinking that starting with a quiet blower will be half the battle, the other half will be softly mounting it (think engine mounts in a car) to the stove sheet metal so as not to transmit vibration.

Comments anyone?

regards,
Eddy

 

[Corey]

I think you're on the right track. Look for a relatively big blower turning slowly, more blades (ie 5 vs 3), and with minimal struts or bars, or guards near the blades. If you're looking for DC speed control, some PWM circuit would be the most efficient, just make sure the PWM frequency is high enough that you don't get an audible whine from that. Lastly, when I mounted my fan, I used some spare sections of door gasket material to avoid metal-to-metal contact and help reduce vibration transmission.

It shouldn't be too hard to design it so all you really hear is the 'whoosh' of the air - then you can control that 'whoosh' with how fast the motor is turning.

 

[DiscoInferno]

A blower with a speed control is very convenient for adjusting the loudness. I have 2 standard shaded-pole blowers in my Ultima, and at full speed they are quite loud. So I dial the speed down when I'm in there, and turn it up when I leave. The 60Hz hum and the sheet-metal vibration I've had mixed success with. The Ultima, despite having an official blower option, has no apparent mounting point. So I just have them set back near/against the back wall, and then wiggle them around to try to limit humming and buzzing. Mixed results at best; if you don't want any hum I agree to avoid standard AC blowers. On the other hand, I have a larger AC blower in the basement that pulls from the fireplace via a duct; it has proper rubber mounting feet and makes little more than a whoosh.

 

[rhetoric]

(this post is also on the "generic blowers" thread)

"Well, I think you're in luck -- I've been your guinea pig. I think our stoves sound similar, too. I have a Lopi Endeavor and most of the Lopi and Avalon models use the same blower (both owned by Travis I believe) so the holes are probably the same size.

My obsession is not quiet, but cheap. I wasn't about to pay $250 clams for a OEM blower that some of you say craps out too fast, so I finally went to Grainger and bought a 4C745 single speed by Dayton (listed on your website). It's a "transflow." It is a really well built fan. I don't know anything about evaluating the quality of electrical components, but a buddy who teaches at RIT said it seems like a really good one. Extruded aluminum casing, built in fan to cool the motor -- they even balanced the blades (making a very small cut out one one of the blades to even it up). You'll have to wire a plug to it.

I liked the enclosed nature of the dual type blowers, but mounting didn't seem as easy. My blower opening is on the bottom and is almost exactly 12 inches long (about an inch or so wide). The Dayton is a little smaller than the hole (a 1/2 inch on either side) but I guessed that that might be a bit less noisy than a blower that was a little bigger than the hole (avoiding the turbulance of blowing on the stove instead of in the stove). I still look to "plug" the openings on the side w/ a magnetic plate or some such. The holes on the fan line up perfectly w/ two of the predrilled holes so it only took two metal deck straps to hang the fan under the stove. Couldn't have been easier.

As it happens, I hung the fan just a hair under the stove so except for the straps which are bolted tightly, there is no vibration on the stove. I might be getting a bit of turbulance noise, I suppose, but I haven't gotten around to redoing the straps so it can hang tighter. I, too, was worried that the contact between the blower and stove might amplify the vibrations. My straps are also a bit thin -- the blower hangs at an angle because the straps have a slight flex. It's a very slight angle, but the housing is not touching the stove. It's not the prettiest fan, but bolted underneath the stove you have to be on the floor to see it.

Performance? Whoa! I have been ready to give up on the Lopi. Just wasn't warming the house in bitter cold weather. But our stoves were DESIGNED to use blowers. With all those chambers around the stove if you don't use a blower it's like heating inside an insulated box. I saw enough testimony on this site that it made a difference, so I decided to spend some loot.
The fan really pumps out the heat. W/ the blower on low, we have massive hot air and the whole house is now comfortable. I still haven't tested it in bitter cold.

Noise? Not bad. Short of putting the fan in the basement and "ducting" it somehow, I think fans and noise just go together. However, I am using a variable speed plug-in rheostat so I can lower speed and noise. If the house is cold (in the am) I build a hot fire, turn up the fan, warm the house fast, then back the fan off to a whisper. Once at temp, the stove/fan doesn't need to work nearly so hard so I can turn the fan down. I think the Dayton specs at 300cfm, but I'm sure I haven't used it on full blast yet. In any case, while there is a bit of noise, turned to where I need it it doesn't mask conversations. I might have to run it a bit higher in the bitter cold, but it's not nearly as noisy as some fans I've heard.

Most importantly, I'm only out $100 clams total and I had the satisfaction of tinkering.