[A930Rocket]

It's definately a code violation when the flue pipe doesn't go up hill all the way.

Our last house was 5000 SF and had a single propane fueled Rinnai HW heater located on an exterior wall. We never ran out of HW at any time, although our plumber suggest installing two of them during the build. It wasn't a 90%+ efficiency type like Ian's, but it worked great like I said. It came with a wired remote that allowed us to change water temps from the owners bath.

Tankless also takes up less room if that's an issue.