We chose this particular model for two reasons: First: our gas line is 1/2" in diameter, and most tankless heaters are 3/4" in size. the second reason is we wanted to free up more space in our garage so we elected to have the outdoor model. We have a 2-bath home and haven't had any issues at all when using both bathrooms at the same time. This was a self-install and was a breeze. The instructions were easy to understand, but if you are not handy, please hire a plumber to install it. Having said that, there are a number of You Tube videos on how to install a Noritz product for reference.. Edgar I. San Diego, CA. Wed Oct 27 2021