Installed 5-ton two zone, two stage, Carrier R-454B system. Installed new disconnect box and wiring for the condenser. Installed new secondary drain pan. Build and installed new supply plenums set up for the zoning system, reusing the zoning equipment. Built and installed new return plenum with new Aprilaire media filter. Sealed all ductwork connections with mastic/hardcast. Installed new gas pipe and flue pipe connections for the furnace. Rebuilt primary condensation drain and installed new SS2 and SS3 safety switches. Cleared primary drain with CO2 and primed trap with water. Pressure tested system with nitrogen and pulled a vacuum. Installed two Ecobee Pro thermostats, one upstairs and one downstairs. Charged AC with R-454B refrigerant. Tested operation of system. Everything is working at completion of installation.