The outlet pipes would not tee back together under the floor. Otherwise none of the fixtures would stop running if you turned off just one heater (either heater).
(One morning on WRKO Radio) The tub's not clean! Let's remodel the bathroom.
(One afternoon on WRKO Radio) It's time for an oil change. I'm going to trade in the car for next year's model.
having 2 w/h's in series i believe is the most energy efficient.very easy to tell how. c/w in h/w out to c/w in on 2nd w/h then h/w out.The #1 w/h is the work horse it's the one doing the most heating the 2nd w/h is basically a storage tank but will heat if needed.just having a bigger on will help but 2 in series is the way to go.