Rinnai Sunmaster tank installed as part of Hills evacuated tube solar hotwater system. Tank failed due to corrosion at cold water inlet and was replaced under warranty. Replacement tank has failed within warranty period due to corrosion at hot water inlet in the same manner as before. No advice on first warranty that our water quality was an issue. They are fitted i believe with sacrificial anodes. Warranty only covers one purchase not the quality of the product. Suspect poor quality metals being used at connection points.
Not worth wasting your money on, by something that's quality and compare warranty to purchase price.

I’ve reported that the pump on our Sunmaster 26 has been running all night 3 times since we moved into our new house 18 months ago. Rinnai tell me there’s nothing wrong when there clearly is. The pump whines all night. And you can hear it from our bedroom upstairs. It’s infuriating! Our guest room is downstairs on the adjoining wall and guests complain about the noise too. I do not recommend this system at all!!!!!!

I also fail to understand why the pump runs in the middle of the night. The electricity bill probably negates the benefit of having the panel in the first place.

Rinnai please take this seriously for once and do something about it!!