
3) On highboy furnace models, remove the burner access panel. This panel will be the upper access panel on the front of the furnace. On lowboy models, remove the front access panel. On horizontal / counterflow models, the burner is mounted on the front surface of the furnace. 4) Remove the three (3), 5/16 in. brass hex machine screw nuts and the three (3) steel flat washers from the threaded studs protruding through the burner mounting plate on the furnace. Retain this hardware for later reuse.