Need help with ventalation and duct question

Oh and if at all possible go to a Plumbing or Heating supply house for 1/4 the cost of at Hydro store and 1/2 the cost of at a hardware store

Babalou said:

Guys: I'm in HVAC, if you want quiet, a 4" is the way to go. A 4' duct will flow 100 CFM and stay quiet. and if you have a 10' x 10' room w/ 8' ceilings, that = 800 cu FT, so you will make a COMPLETE change of the air inside in 8 mins. Further more you do not want ANY duct over 25" in length, and any 90 deg turn will add 5' to the legnth. If you do exceed 25 step up a size to 6" (150 cfm) or 8" (250 cfm)

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Thanks! Been looking for a rule of thumb. (didn't feel like getting out the HVAC book, its just a task of my job, far from the main topic)

(just gotta split hairs, I'm in that kinda mood, so pay little attention!
May not be a complete change over, some corners may stay stagnant.)

Also feel a 100cfm 4 inch fan is louder then a 100cfm 6 inch fan.
Hey, what style of fan is the quietest? cage, axial, etc?

++rep

Now, see, that shit should be stickied right there.

And the thread originator should hit the thread with some tags, HVAC, cfm, size, rate, ratio, 4-inch, 6-inch.. whatever anyone thinks could help for doing searches and stuff.

Seamaiden said:

Now, see, that shit should be stickied right there.

And the thread originator should hit the thread with some tags, HVAC, cfm, size, rate, ratio, 4-inch, 6-inch.. whatever anyone thinks could help for doing searches and stuff.

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I cut-n-pasted it into my notebook. gotta compile it into a nice PDF one of these days.

yeah i agree big loss of cfm's

added the tags. Very informative posts.

I can only add a couple. You guys give good thread.