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Posted by dadiOH on September 15, 2007, 8:56 am
Lacustral wrote:
> I'm planning to use an inline fan for a range hood - I'm going to
> have the canopy made by a metal fabricator. I'm putting the fan in
> the attic.
> I'm looking for something
>
> - about 300 CFM max
> - can be speed controlled about all the way to 0.
> - doesn't make a hum or whatever when speed controlled.
> - Absolutely as quiet as possible.
>
> I've heard that if you compare a small fan with a large fan that's
> turned
> down with a speed control to move the same CFM as the small fan,
> the large
> fan will be quieter.
>
> Somebody at Fantech told me this wasn't true, that the noise just
> depends
> on the CFM the fan is moving. I don't believe this (she said other
> very dubious things), because I've heard elsewhere that a larger
> fan will be moving with a lower RPM when it's moving the same
> amount of air, so it would be quieter.
>
> So, I figure I'd get about a 300 CFM fan and turn it down with a
> speed control. My range is very small and it doesn't need a big
> fan.
>
> Some fans make a low-voltage hum when you use a speed control on
> them.
> Fantech said their fans do. Someone at Broan told me their inline
> duct
> fan doesn't have a low-voltage hum when speed controlled. I don't
> know how big of a deal the low-voltage hum is, compared to the
> noise from the fan
> motor.
>
> What inline fans are quietest? They don't have a standard way of
> testing
> the noise from them, unfortunately.
>
> I know stuff about reducing the noise that's moving through the
> duct -
> duct silencer, liquid soundproofing you can spray inside the duct.
> Etc.
> etc. My question though is about the quietest *fan*.
I have no idea which is quietest; however...
1. I have a Broan. Don't recall the CFM but it is maybe 10-12". No
speed control
2. It is about 25' from cooktop
3. The only way we can tell it is running is by looking at the
switch...I used a switch that lights an LED when the switch is on.
Be sure your hood fabricator includes a grease trap - that's just
coarse wire mesh - that is easily removed for cleaning.
--
dadiOH
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