"Charles Spitzer" wrote in message
...

wrote in message
...
I will be building a 100' long home with water usage at the two ends of
the
house.

At one end will be a mostly over the garage apartment for my daughter
with
kitchen, bath, laundry. Also there will be a bath with on the first
floor
with our kitchen and also laundry and utility tubs in the laundry and
garage.

In the middle will be a 2nd floor guest bath.

On the other end will be a first floor master bath with shower and 72"
jetted tub (Venus II).

A priority is not to have to wait "forever" for hot water to reach a
spigot, especially at the kitchen & lavatory sinks and utility tubs.

I am planning to have a hot water heater in the garage and another under
the master bath (crawl space here will be about 6 feet high due to land
slope).

How large should I make each water heater. Should I have a separate
additional heater for that huge tub and only turn it on when needed?

Many thanks for any knowledgeable help!

some sort of return loop would be easier, and cheaper to run than 2
heaters.

regards,
charlie
http://glassartists.org/chaniarts




A recirculating loop with large primary tank is certainly a good way to do
it (lower up front cost) but if the hot pipes are not very well insulated,
the recirculating line will cause a lot of heat loss and wasted energy
(higher long term cost). An on demand recirculating pump activated when you
push a button as opposed to a pump on a timer or thermostat is more energy
efficient in my opinion (though not as transparent or instant)

Two tanks is acceptable, I would consider plumbing the second tank in series
with the first if located like you say as opposed to two parallel hot
systems aside one cold. The series tank will allow quick delivery of hot
water to distant fixtures and once the hot water from the primary tank
started filling the second one, it would not need to heat as much water
making the system more efficient. You would also effectively have the full
volume of both tanks available to fill a big tub. Hot water branches can
extend from the output of either tank. This configuration may also buffer
the tub/shower supply from other uses like laundry (connected between the
tanks)

A single on demand heater positioned more centrally in the house or two
smaller units plumbed in parallel are also options.

My Guess: A 50gal primary tank and a 30 gal secondary sound like it might
suit your needs. Of course you can go larger but it will effect your energy
bill. The secondary tank only needs to be somewhat larger than the volume
of water in the hot pipe between the two tanks (which isn't much) to work
(prevent any cold water surges at the far end of the house) plus any
additional volume of water you think the attached fixtures need before the
tanks have time to reheat.

There are pros and cons to each configuration. Choose based on price and
performance you feel comfortable with