I have a gas heater in my 1 level apartment. It is in the corner of a room blowing down and straigt out. I would like it to blow more into the center of the room, so I would like to use foam board to do so to make a triangular box. Is this a good idea? I read on the back that its "combustable". Did I buy the wrong stuff? It is "Super Tuff-R Polisocyanurate Insulation". "A polyisocyanurate foam board insulation with reinforced poly/aluminum foam facers on both sides." Any help would be appreciated.