In this video, I talk about return duct, you need 200 square inches per ton in order to keep the noise down across you return grill. you air conditioning and heat pump system has to breath. the math is 200sq in X 3= 600sq in
always size return duct work at .5 static pressure
use a duct calculator the more grill space, the quieter the system will operate more efficient

Thanks for watching!
- David

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