[smagown]

When I pulled my basement airs from my first two bays, I uncovered the return air plenum running from the front wall of the front bay to the rear of the steps. The front heat exchanger for the Aqua hot sits on top of the return air box and you can see the intake in the pic. I removed the return air box so I would have a pass thru front bay after discarding my basement airs in lieu of roof airs. I'm now remounting the heat exchanger on the bay wall and running a smaller return for it back to the air filter behind the mid entry steps.