I have a 3 ton evaporator unit that is rated at 1200cfm airflow, but my return air grill is only 14" x 24". Am I correct in thinking that this is too small? I have read many places that I should expect to get about 2cfm/in² from my return air grill, and following this, I expect only to get about
2cfm/in² x 14in x 24in = 672cfm
which is barely over ½ the rated 1200cfm of my evaporator unit. What other considerations should I be making? I have a house with about 1400-1500 ft² living space, and this fairly new unit does WILL NO cool my house in 90° heat (it can only maintain the inside temperature and sometimes not even).
I am wondering if my return air is a bottleneck for my system.
Thanks in advance!