Sorry for the confusion but the units work out. I have seen a couple different versions of the motor heat equation. The one I have takes the brake horsepower and divides it by the motor efficiency. I have seen others that just use the motor nameplate horsepower and convert it to BTUH, but that gives you the highest possible value. It would seem that brake horsepower would be more accurate.
I have ten 15-HP motors in the air stream, so a straight conversion would be (150 HP)(2,545) = 381,750 BTUH. With both motor and driven equipment in the airstream, motor efficiency should not matter.
My other equation is the sensible heat transfer for air. The 1.08 converts mass to volume, specific heat, etc. The units all work out.
So if I use the number above: BTUH = (CFM)(1.08)(Delta-T). I would get a delta-T of 7.85 degs with this calculation.
The reason I question this is because the "rule of thumb" is usually around 2 degrees of temperature change added by the fan. I think it is the high static pressure that is driving this delta-T way above the "rule of thumb." I just needed a reality check on my calculation.