On Aug 7, 11:52*pm, Smitty Two wrote:
In article ,
*"Bob F" wrote:





"Andy Asberry" wrote in message
.. .
On Thu, 07 Aug 2008 09:46:19 -0700, Smitty Two
wrote:

SNIP

This problem is a minor modification of the jacuzzi heating question,
and the same logic applies. Every speck of heat lost through the night
has to be replaced. Do it in small chunks, or do it all at once. Same
amount of energy is expended, disregarding the *very* minor difference
noted (that rate of heat loss decreases as temp. differential decreases.)

I believe you are on the right track. I have nothing to back up my
theory but here goes. It seems to me you only save after the tank
water temp has cooled to incoming water temp. Then the time off would
be the same as never having turned it on. This, assuming you have done
the other things such as insulation and stopping leaks.

How many times in this thread have you made the same, obviously erronious
claim?
You save any time the water in the tank remians cooler than normal. In many
places, the water would NEVER even reach the incoming water temp, which is
lower
than room temp.

You responded to Andy. Are you addressing me?- Hide quoted text -

- Show quoted text -

I don;t know, but I'd say the comment could apply to either of you.
As Bob F states, you save energy anytime you allow the water in the
tank to cool down to a lower temp than it would be at if the heater
was left on. Again, I'm not debating whether the savings are
sufficient to make it practical. But you can't deny the physics
here.

From a physics standpoint, it's the exact same thing as setting back
the temp in a home overnight to save energy. And the DOE clearly says
it is worth doing, but without seeing actual numbers, we don't know
exactly how much anyone is actually going to save.