Return air on new air conditioner/furnace
We are adding on to our house and the air conditioning and furnace install has been stressing me out! I feel like I don't know enough about this stuff to see if it's done right so any help would be greatly appreciated! I apologize in advance if I'm using the wrong terms for anything.
The air handler is installed in the attic on its side and the return is directly connected the bottom of the air handler. There really isn't a return box, just the bottom of the air handler is mounted to some 2x6 studs (covered with sheet metal) which is where the return grill is. So I guess the 2x6 cavity is the box. The filter size is 14x24x1.
Does this seem right? Here is what bothers me:
1. The opening in the air handler for the return is about 24x20, but about a 1/3 of the intake is blocked by a large 6x6 (to which the air handler is mounted). So effective, the opening is only about 16x20. Is this normal? Seems like the air handler intake should be unobstructed. I'm attaching a picture of the air handler looking out the bottom. You can see the large 6x6 (with the yellow wire) blocking the intake.
2. This is the only return air. Doesn't it seem like there should be more? I'm in CA and it seems like many of the tract homes here only have one return??
The furnace is a Rheem 5-ton, RGPS-10NBRJR
The A/C is a Rheem, 13AJN60A01
Thank you VERY much for any help!