I'm planning on installing a portable spa in a small 12' x 12' sunroom (which is now unconditioned). I will be using screened double hung low-e windows and doors in the room.

Obviously, I need an exhaust vent, and makeup air if I want to keep the windows closed. I don't feel heating the room will be needed as much as cooling in the summer. (located in the mid-atlantic region)

I could open the sliding patio door between the sunroom and conditioned house for some heating and cooling. But I also have a spare Aprilaire fresh air exchanger that I could incorporate in the vent system.

So what are some setup and control options for exhausting spa moisture, making up with cooler air using existing HVAC and in turn making that air up with the Perfectaire unit? Looking for a way to switch from either conditioned air or outside air easily.

PS. I'm a retired HVAC-R commercial service tech, so will be doing the work myself.