I started the 2 package cleaning with the furnace side of both systems. The master bedroom furnace: I removed the burners and inspected the heat exchanger, there’s a decent amount of rust which isn’t uncommon for a 20 year old unit. I smoke tested the heat exchanger and have some blow back in the left cell, this is indicating that there’s a crack in the heat exchanger or the metal has split apart at one of the seams. Tested the igniter, tested good. The pressure tubing running from the collector box to the drain trap is cracked, this will start to cause problems come fall/winter. I checked the exhaust readings. The carbon monoxide is in normal range at 26ppm in the exhaust. But the excess air readings is at 120, this goes along with the failed smoke test and the heat exchanger not being fully closed up. The temperature rise is normal at 48*. Due to the age of the furnace and issues found, I recommend having my supervisor stop by to go over options on the system. The master bedroo