Removed existing tankless unit, sealed vent holes on the exterior with hydraulic cement, removed all venting underneath back porch. Installed new dual 80 gallon Rheem Pro Terra units, Ion 6 filters on each cold side to units, leak guards on each, isolation valves for cold, hot, and recirculation pump. Installed Halo 5 whole home filtration system with a bypass and drain discharge ran to the exterior. Everything is working properly but will return Monday for additional work and to touch up a few things on units.