The time has come to replace our existing tankless water heater, And I'm about to pull the trigger on a Rinnai 5.6 gpm gas unit. My only reservation is that it sells for about 700 bucks, very low for a tankless water heater. When I was asking around, most plumbers said the units are around $2,500 bucks for a quality one, so I am just wondering why this one is so cheap. It's definitely got no frills but I don't need any of that as long as it works and it's reliable. This particular unit has pretty good reviews And I hear Rinnai is a quality brand, but I just want to make sure before buying it. I'm also a bit confused on condensing vs non condensing models, and what the mbh number means.