Found dirty flame sensor. The furnace would fire off then shortly cut out. I pulled the flame sensor out and cleaned it. Put it back in and the unit fired off and went through the complete sequence of operations. At this time the heating has been restored. The unit is back up and running at this time. Material list for media filter addition Collars-14, 10, 12, 8, 6, 20x25x4 media filter Transition for media cabinet Plenum Duct board and sheet metal to make repair on existing plenum