Restrictions in return duct?

[pm4589]

Originally posted by dash

So we need 229 cfm per space for 1600 cfm,which would be a Friction Rate of .15 per hundred

I agree with what your saying here but was just wondering why you use .15 per 100FT? Is that due to the wall material?

[dash]

Originally posted by pm4589

Originally posted by dash

So we need 229 cfm per space for 1600 cfm,which would be a Friction Rate of .15 per hundred

I agree with what your saying here but was just wondering why you use .15 per 100FT? Is that due to the wall material?

Using the ductolator to determine FR,14"X3.5",wall space,looking at it as a 14X3.5 duct,if we had 229 cfm,it would be .15 FR per 100' of duct.

Since the original poster has stated they are high wall returns,then 10 ft of wall space/duct,would be .015 Friction Rate.

[pm4589]

Right after I posted I figured it out.....
Couldn't delete in time.

So were looking at about 620 CFM @ 700FPM

[Edited by pm4589 on 03-04-2005 at 02:46 PM]

[dash]

Originally posted by pm4589
Right after I posted I figured it out.....
Couldn't delete in time.

No problem,since you understand ,please post on this site more often,we can all use the expertise.