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Re: A Plumbing Problem



Isn't this acting like resistors in parallel? I always get fuzzy over the
electricity/plumbing analogies, but it seems to me that if the pressure
(voltage?) is the same but the flow (current?) is different, we're talking
about parallel. In which case, the smaller resistance would have the largest
current.

The smaller inlet pipe produces a greater impedance to the flow of water
than the larger pipe. Assuming that both tanks are connected together at
the outlet end and are feeding the same system they will act like resistors
in series. On one branch is a tank with small pipe in series = large
resistance. On the other branch is a tank with a large pipe in seres=
smaller resistance. The total pressure drop across both branches is the
same and thus the smaller resistance will have a greater flow of water
through it. Since the tanks are identical the one with the greater flow of
water through it will run out of hot water fastest.

-----Original Message-----
From: Allen Shotwell <rshotwel@ivy.tec.in.us>


A friend of mine called with an argument he is having with his plumber. At
his business (a health club), he has two water heaters (or should I say hot
water heaters?) of equal capacity. Both have an outgoing, hot water pipe
that is 3/4". One has an incoming (cold water supply) pipe that is 1.5"
and
one has an incoming (cold water supply) pipe that is 3/4". He says that
the
water heater with the larger supply line runs out of hot water faster and
claims that it is because of this larger supply line. His plumber says no.

I have monkeyed around with the problem some this morning. What do you
think
gang?


BTW both heaters were installed at the same time. One is not a good deal
older and (by extension) a good deal more crusted up.




R. Allen Shotwell
Chair, Science and Math
Ivy Tech State College
Terre Haute, IN USA








Jim Riley
Department of Physics
Drury College
Springfield Missouri 65802
(417) 873 7233
e-mail: jriley@lib.drury.edu
fax: (417) 873 7432


R. Allen Shotwell
Chair, Science and Math
Ivy Tech State College
Terre Haute, IN USA