Actually........
I ran into this last year when a customer bought his Rinnai off the internet auction site from an outfit in New Jersey. They sold him a larger model Rinnai that would give him more water flow than the smaller model. Unfortunately taking our groundwater temp here in PA this "larger model" will deliver the exact same flow as the smaller one, just use more gas to do it. That being said his price on the larger Rinnai was the same as my price for the smaller model number, but he also paid shipping and handling. IF you can find someone to sell you one anyone can BUY a Rinnai. However, and this is directly from Rinnai when I called them, the warranty is void if the unit is installed by anyone who is not a certified installer.