Not normally a review writer but... After having a prior Rinnai propane outdoor unit running heating and domestic water, then in my most recent house I replaced two 60 gal CNG standups with this unit. It is tied in with a 30 gal reservoir/storage tank and a recirc pump to maintain tank temp (not a domestic hot water loop). I have gas experience and previous mechanical/ building cert. so install was fairly straight forward. Planning and design are important. It condensed down a massive setup into a small compact space saving design. Ultra quiet and as advertised, unlimited hot water. Had a plumber I talked to give me a spiel about another no name brand he uses, having to upgrade my water pump and pressure tank etc. Be sure your installer knows what they are doing or it will definitely be a bad experience. Done properly you will be pleased.Update: Over one year later, no problems or issues with my heater. Still love this unit.