Removed old equipment and installed new Rheem 3.5 ton full gas system. Installed 2 new return boxes, new emergency drain pan, new pan water safety switch, new coil water safety switch, new 10” return with new 14x20x1 filter grille, new thermostat, and new composite pad for outdoor unit. Reconnected supply plenum, high voltage, low voltage, drain line, gas line, vent pipe, and return ducts. Tested system operations in heating and cooling, set proper charge.