On Mon, 18 Feb 2008 10:55:41 -0800 (PST), N8N wrote:
I think it needs to be *at least* 6 inches above the floor, you don't
want it to be too high though in case you are in the room when it goes
off. I assume you have a floor drain in this room?

Hi Nate,
It's a garage that drains down the driveway.

This reference also says "at least" six inches off the floor.
http://www.high-performance-hvac.com...ance-tips.html

This one says "within" six inches of the floor:
http://www.friendlyplumber.com/plumb...er_heater.html

I'm going to tell Bill to decide to put it at the 18 inch mark above the
elevated step; otherwise it would need a horizontal length which would be
bad.

Thanks,
Donna