In the attached picture, the bottom proposed return header traverses a chimney alcove of 5'-6' in length. Would it be poor practice to route the pipe across the opening say 2 feet or so above the floor? It'd be 4 elbows and much more pipe if it went up top. The only access required in there would be to sweep the chimney. Might put an expansion tank in there. I imagine I would have to support the pipe in the middle off the floor somehow. Thanks.