Removed old equipment and installed new Rheem 4 ton full gas system. Installed new return plenum with 20x25x4 filter, new emergency drain pan, new pan safety switch, new coil safety switch, new thermostat and new composite pad for outdoor unit. Reconnected supply plenum, high voltage, low voltage, drain line, gas line, vent pipe and all return ducts. Tested system operations in heating and cooling, set proper refrigerant charge.