WSB furnace inspection. Found system to have cracked heat exchanger, high temp rise, high amp draw on inducer motor, single wall flue pipe, no flood protection and dirty blower. The system has roughly 2 ton of return air and 3 tons of supply air with a 70kbtu furnace on a 2 ton ac. Temp rise to high likely because furnace to large or system short on return air. Heat exchanger is back ordered by manufacturer with no time table for delivery. Recommended replace equipment given age, and parts not being available for repairs anytime in the near future. Informed customer of cracked in heat exchanger, advised due to safety concerns not to operate the heat, left thermostat in off position. Customer getting a quote on Saturday for replacement.