For this job I replaced a leaking old tankless water heater. I installed a new Navien tankless with recirculating tee cross over. I installed the cross over tee in the master bath right side sink. Will help water be more instant upon opening hot water side. I ran 2 pvc vents to exterior of home and capped off old flu vent. I also ran condensation and tmp lines outside. I make all new gas connections and installed 2 cut offs for the water heater. I also installed a check valve on the cold side at the water heater. I installed new expansion tank and pressurized to 70 psi. I set temperature to 120 degrees and tested everything. Left work area clean.