Vapor barrier location question
I have an air handler in my attic space. The attic is out of the envelope and I would like to build a rigid foamboard box around it to maintain a more even temperature. Should I vapor barrier (Fypar) the inside of the box, the outside, or neither?
It blows heat in the winter and AC in the summer. Of course, its surroundings are just the opposite. Any input would be appreciated.