Based on our findings today, it might be time to think about getting a brand new system. Today we came out for the only system not heating properly 2001 ICP 75k natural gas furnace located in the attic. Cycled equipment from attic found high limit switch opening. Inspected heat exchanger with digital camera found crack on second eye lid on right side of cell. Brought client into attic and showed them findings and tagged equipment unsafe to operate in heating mode due to carbon monoxide fumes. System has minimal flood protection and gas line is not up to current code sediment trap was installed wrong. Scheduled install supervisor to give options on updating equipment.