I just got delivered a Takagi T-H3-DV with 0.95 energy factor. This is a condensing unit so it just vents with 3” PVC pipe.
http://www.takagi.com/products/tankl...ters/t-h3-dv-n
I am moving my tank from the attic to the garage. I have copper pipe now but I think I will try my hand at installing Pex. I am going to add a ½ return line for the recirculation pump. I have an aquastat and a trimmer for the recirculation pump. I am going to put contact switches on the bathroom doors and use my home automation to turn on the recirculation pump 10 min when the bathroom door closes.