Homeowner Forum / Construction / February 2006

With a run that long a tankless is a good choice.  Go with 3/4" risers.

R

with pressure drop you are addressing an insignificant issue
for the most part unless you have some kind of 15 nozzel
shower ... in that case you would simply run larger pipe
(3/4") not a big deal  at all.

the actual issue is heat loss through long lines from the
water heater to bathroom sink faucet so you have to run the
faucett a long time to get hot water to wash your hands...
then all the hot water in left in the line cools down, wastes
heat.

the solution for that is an instantaneous water heater under
the sink...   for a bath its not the same issue because you
use so much hot water for a bath that whats left in the lines
to cool later is not significant.

on the pressure issues though... your city water pressure is
probably between 40 and 60 psig...   loss in 1/2" line at
usual flow rates required for a bath would not exeed 5
psig..insignificant.   If you want virtually no pressure loss
go to 3/4" lines...most homes do that for the mains, then
branch with 1/2" to the fixtures, bath tubs and showers will
have 3/4 to the fixtures in virtually all cases.

Phil Scott

If you want to flush and shower at the same time, install the larger
dia lines.  Cost 2X but worth it.

Rock