[RP TownTalk] on-demand hot water systems

[Sarah Wayland]

We have one - a Bosch "Tankless Hot Water System". We've had it for
nearly 10 years.

Advantages:

(1) The tank never rusts out. Indeed the only maintenance we've had to
do is replace a filter on the intake line that collects silt before
sending the water through the heater unit.

(2) We never run out of hot water!

Disadvantages:

(1) Requires a larger diameter vent pipe. Our vent pipe runs half the
length of the house before it gets to our chimney, so replacing it was
a Big Deal.

(2) The electrical wiring in our house was not adequate to support the
higher current the electric unit draws, so we got a gas unit. The gas
unit is less efficient than the electric unit.

Differences (neither good nor bad, just different):

(1) The way you adjust the temperature of the water is very different.
The water must flow at a certain rate for the heater to turn on. So
you start by turning on the water until the flow is high enough for
the heater to turn on. Then you add cold water to adjust the
temperature to the correct set point.

(2) The water coming into your house is warmer in the summer than in
the winter. The unit heats the water a constant amount - so if your
water is 40 degrees, you can set it to heat it by 60 degrees, so that
the "hot" water is 100 degrees. But in the summer, if you leave it at
+60 degrees, the water coming into the house is closer to 65, and you
get hot water that is 125 degrees. That's a lot hotter than 100
degrees! This means you need to adjust the amount of heating you want
with the seasons.

There are probably a lot more issues I haven't mentioned above, but
others can chime in with things they've discovered. Overall I'm
extremely happy with the unit, and in particular with it's durability.

-Sarah