I have a bryant 353BAV 92.5eff 80K furnace and 116BNA/CNPV AC codenser coil being installed in my attic. The prior installation was incorrect as the installer pointed out because the supply of the plenum were taking off the height of the coil. Now with an encased coil, how high should the plenum be.

I have 12", 10" and 7'' duct takeoffs from the plenum. Currently the 12" and 10" takeoffs will sit 2" above the coil case.

Thank you,