Once we made the decision to install a tankless water heater in the home we were building, we had to decide which brand.   On the advice of a friend who has a tankless,  we began to research the Rinnai tankless water heater.  After comparing it to other models such as Bosch and Rheem, we decided to go with Rinnai. They offer several models based upon your needs.  We went with the RL75eP model, which met our criteria.     One nice feature,  is that if you need to, you can connect two units together.  However, one unit has been sufficient for our  2 1/2 bathroom house.  We have yet to run out of hot water (which can be a bad thing, when filling up a deep tub).    Another choice, you will have to make is whether to install a outdoor unit or indoor unit.  The positives of the outdoor unit is that it’s less costly to install (you don’t have to vent it outside)  and it frees up space inside.   If you live in a colder climate, then you might have to go with a indoor unit.   We went with a outdoor unit but I wish we had installed a indoor unit in a more central location.  This would of lessen the time it takes to get hot water to some of the outlets.   So far, we have been pleased with our tankless water heater.   

FYI: The  default maximum temperature is 120 degrees.  If you would like to increase the maximum temperature,  there is a simple work around.  

About Rinnai:  
Rinnai is the 2010 Builders’ Brand Leader as chosen by home builders in Builder Magazine. The Alliance to Save Energy awarded Rinnai their prestigious Super Nova Star Award for energy efficiency and Bestcovery.com chose Rinnai as The Best Tankless Whole-House Water Heater.