Original message
| critterdoc
 |  "Ideal cross sectional area for return air on"
, posted Sun 2 Nov 19:12  
I would greatly appreciate advice on the ideal cross sectional area of a wall mounted air intake grill/duct which will be is feeding directly through a wall into a Lennox 16-28 or 20-28 PureAir unit which will be attached directly to the inside components of a Lennox Signature collection" furnace and 4 ton Elite Series XC16 system.
Wall space is no problem for the intake grill and filter, but shortly after penetrating the wall the intake air will all be delivered into either the 17.5" x 28.5" (499 square inch I.D.) or 21.125" x 28.5" (602 square inch) I.D. of either one of two PureAir Air Purification systems. I must assume that more is better but do not understand HVAC theory enough to be sure.
The previous 20" x 30" intake grill produced a lot of noise on the old 4 ton system, and I'd like to try to mute that noise and increase efficiency of this reportedly "smart" system. I've had several different local opinions on this issue and am more than a little confused about something that I would guess is more a question of physics than anything else.
I must assume that larger cross sectional area is better but no matter the size of the intake grill, all of the air intake air will enter the restricted area of the Purifier after traveling no more than 12 inches.
Thanks for your advice.
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Replies:
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| Hube
| "Re(1):Ideal cross sectional area for return a" , posted Mon 3 Nov 09:29:
If it's 600 sq. in. right at the unit, it will be best with a minimum of 800 sq. in.right at the return grille. Also the main cause of the noise is not only because of the smaller restricted grille, but it's because the unit is TOO CLOSE to the return grille. Some 'acoustic' (internal) lining would be sure to quiet it somewhat.If using the lining, make sure you further increase the grille size accordingly.
[this message was edited by Hube on Mon 3 Nov 09:31] |
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