Downstairs system : Installed 3.5 ton R-454B condenser and evaporator coil. Installed Carrier gas furnace with new gas pipe and flue pipe connections. Installed new secondary drain pan. Rebuilt primary drain with SS2 and SS3 safety switches. Built and installed new return plenum and extended supply plenum. Removed master bedroom duct from triangle and spliced into home run into supply plenum. Attached all existing flex duct to new plenums. Sealed all connections with mastic/hardcast. Installed new disconnect and wiring for the condenser. Leveled on new pad. Pressure tested system with nitrogen and pulled vacuum. Cleared primary drain with CO2 and primed trap with water. Charged AC with R-454B refrigerant. Tested heating and cooling operation. Everything is working at completion of install.