Removed dual 50 gallon gas water heaters that had multiple failures including leaking recirculation pump, leaking relief valves, and failed thermal expansion tanks. Installed new Navien NPE-240A2 tankless water heater. Modified existing water lines to accommodate new water heater configuration, installed ION-6 inline scale filter to protect unit from scale buildup, capped old exhaust vent and modified existing gas line. ran approx 30ft of 2in PVC exhaust piping and intake vent to the exterior of the home. Sealed penetrations with silicone and added condensate discharge pump to new tankless. Tested system for leaks and verified proper function. Also installed and programmed navilink wifi controller. Insulated water lines and dedicated return line to protect from freezing in unconditioned space. Still unable to locate source of water damage that had occurred in the hallway and pantry.