Installed new straight electric upflow mobile home air handler with heat kit. Built and installed new supply plenum. Sealed connections with mastic and hardcast. Installed 2.5 ton R-454B Payne condenser. Installed new disconnect box and wiring for the condenser. Pressure tested system with nitrogen and pulled vacuum. Poured water down condensation drain to test flow. Charged the system with R-454B refrigerant. Tested heating and cooling operation. Everything is working at completion of install.