cfm ratings

[sundancer245]

was in lowes today looking at inline duct fans, they had 2, a 6" and an 8", the 6" was rated at 250cfm and the 8" at 500cfm ...this seems kinda high to me from what ive seen looking around the net for fans, can i expect that to be acurate? my room is about 1000 cf, can i expect that 8" fan would exhaust my room in 2mins? :confused2:

 

[Tater]

http://lmgtfy.com/?q=cfm+calculator

 

[sundancer245]

ah thats pretty cool thanks tater matches what i figured up, just have to wonder if a 30 dollar 8" duct fan is really gonna move 500cfm

 

[sundancer245]

upon further research it looks like the rating of 500cfm is what it will boost to with a free air cfm of more like 210

 

[greenfriend]

I wouldnt buy fans from Lowes or home depot. the cfm forinline fans ive bought at hydro shops are as follows.

4" - 140 cfm
6" - 440 cfm
8" - 760 cfm
12" - 1060

(can fan cfms are a bit higher with the 12" maxing out at 1300 cfm

 

[StoneyBud]

ah thats pretty cool thanks tater matches what i figured up, just have to wonder if a 30 dollar 8" duct fan is really gonna move 500cfm

Hey sundancer, the pitch and blade size and turn speed are what determine the amount of air moved by any fan. With the right fan, you can have a monkey walk a geared treadmill and it will move the same air the $1000 fan will.

The "cheap" or poorly made motors are the limiting factor in purchasing a fan.

The more expensive fan motors use heavier gauge wire, better motor bodies, stronger magnets, better grades of everything. That results in a more expensive product due to the costs of the materials.

Basically, the less expensive a motor, the less quality it has. This isn't always true, but mostly.

If you look at the range of costs in the size you want, stick to the non-china, European or USA made products in the mid-range of costs and more than likely you'll have a decent product.

This isn't always the case, as I've proven with various products myself, but it's a good guideline.

Good luck!

 

[meds4me]

The short answer to this question is : Yes. IF and i repeaat IF youre application fits that of the fan design in question. Personally I'm cheap and dont believe in buying a Mercedes just cause its German made. I always look at the application and fit my wallet to my needs. Sometimes buying "cheap" is just as good if not better ~

 

[meds4me]

I have a 8" inline for a "range hood" that flows 180 cfm at .08 static. Plenty of flexibility in using something like this 'cause the addition of duct work has already be "designed" into its useage.

 

[sundancer245]

hey greenfriend, StoneyBud, and meds4me, thanks for the advice! for now im gonna run the 8" duct fan connected right to the heat vent in the floor of the bedroom, and exhaust it into the basement below...its all i can afford to get started and should work for now, its an easy hook up and i can modify it later :hubba: