Installed Carrier 5 ton 2 stage R-454B system. Gas furnace and evaporator coil in attic. New disconnect box and pad for the condenser. New gas pipe and flue pipe connections for the furnace. Installed propane conversion kit and set gas pressures. Ran new thermostat wire and installed Ecobee pro thermostat. Built and installed new supply and return plenums. Installed new secondary drain pain. Rebuilt primary condensation drain, added SS2 and SS3 safety switches. Cleared primary drain with CO2 and primed trap with water. Connecting existing flex duct to new plenums. Sealed all connections with mastic/hardcast. Pressure tested system with nitrogen and pulled vacuum. Charged AC with R-454B refrigerant. Tested heating and cooling operation of new system. Everything is working completion of installation.