Turn on flow rates differ but are around 1/2 - 1 gpm so it will not
trickle out hot. I have a small 117000 Bosch and the savings are worth
it , it needs a 1/2" gas line to 10- ft. then 3/4 if further away.
Larger 2 shower units need 3/4 line. Bosch Takagi and Rinnai are the
main names and most are made in Japan. My unit will heat easily 34f
incomming to a hot shower without being set on high. The larger more
efficient units will really handle 3 showers. Ratings are key, the gpm
and temp rise. Takagi has a new unit that is the highest efficiency made
at 92% Ng