I have since determined that 440 CFM is more capacity than I (or anybody would) need. The blower was silly cheap sold as a scratch and dent, without any scratch or dents visible. My suspicion is that a 440 CFM bathroom fan would suck henry homeowner out the vent.
The ducts don't arrive until mid next week and the blower running unloaded is more like a dull roar than a whisper. I will wait until I get it properly loaded with ducts, but JIC I started thinking about how to slow it down.
A simple folded paper air filter sucked up against the inlet port quiets that end down a bunch. I do not expect the whisper line branding is some big lie so it will quiet down with ducting, but running it slower will be even quieter.
440CFM will suck the air out of my back bedroom completely in about 4-5 minutes...
The instructions (yes I read those) advise against using solid state controllers (basically light dimmers). I suspect they are worried about mechanical hum being generated by the dimmer period.
Since I try to hug the planet as much as the next guy, a series cap could drop the fan speed without resistive losses, or hum. A quick calculation suggests the blower motor load looks like 24uF... not a cheap film capacitor...
I think I have some 22uF polypropylene caps (only 63V) that I could experiment with..for a half speed test. If they short out the worst case is the fan speeds up again.
Right now I am putting the cart ahead of the horse since I need to wait for the duct work to determine if I actually have a noise problem.
Always fun around the casa el juan. Life keeps giving me tests.
JR
PS: Still waiting for rain.... Tropical storm barry (oh what a scary name) has dropped less than 1/2" but that about equals the last two weeks of rainfall so all good. I may regret saying this but let it rain. (my apologies to baton Rouge and nawlins who don't need the rain, or the entire MS valley).
