Hi, My Son has a CG-5 Series 12 Gas fired furnace. He plans to run a horizontal single pipe and vent it out a window. He plans to use insulated pipe in an area exiting the window where clearance is about 6 inches from wood frame. The pipe will have a 4 inch slope for the 15 feet it will run. Will this work safely? He wants to free up his chimney for a wood stove that he is putting in his living room. Please respond to deslauri@comcast.net