Picture comes no where close to justice. The verticle object on the left is of course the h20 heater; 15 inches away from the furnace with a 18" long blower housing, not including the rails. I guess it could be rotated and finagled out. However what you really can't see from the picture is that the furnace is installed sideways in a closet, two feet down from the floor of an office area that used to be a garage. Right behind the camera is a wall, the closet doors are off to the right a foot or so. You would literally have to lie outside the closet, 2 feet up along side of the furnace and somehow hook your upper body into a U turn to do any significant work on this thing. If I ran into this after hours with calls backing up I believe I would say you'll have to wait for regular hours and a special quote for the PITA factor.
It ended up being a half *ss PM with a prayer that it would cycle correctly when I was done.