Installed 4 ton R-454B 2 stage Carrier system. Gas furnace with propane conversion. Upstairs system. Installed new disconnect box and wiring for the condenser. New gas pipe and flue pipe connections for the furnace. Built and installed new return plenum with new media filter inside. Built and installed new extended supply plenum. Attached existing flex ducting and sealed all connections with mastic / hardcast. Installed new secondary drain pan. Rebuilt primary condensation drain, added SS2 and SS2 safety switches. Cleared primary drain with CO2 and primed trap with water. Installed Ecobee pro thermostat for the upstairs system. Ecobee lite for the downstairs system. Pressure tested system with nitrogen and pulled vacuum. Charged system with R-454B refrigerant. Adjusted gas pressure at the valve for propane. Tested heating and cooling operation. Everything is working at completion of install.