Installed 3 ton Carrier R-454b condenser, evap coil and vertical gas furnace. New flue pipe and gas pipe connections for the furnace. Installed new 20x25 filter base. Rebuilt primary drain with new p trap and new insulation. Added SS2 safety switch to secondary drain. Sealed supply plenum with mastic and hardcast. Pressure tested system with nitrogen and pulled vacuum. Cleaned out return chase underneath the furnace. Charged AC with R-454b refrigerant. Tested operation of system. Everything is working at completion of install.