"ATP*" wrote in message
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"Ed Huntress" wrote in message
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"Lewis Hartswick" wrote in message
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Stormin Mormon wrote:
Please forgive me while I troll for a moment.....

Is it energy saving to turn the thermostat down, when leaving the
house? I mean, the furnace has to run to catch up when I get home. I
have a way of looking at the matter. I'll explain my point of view
after the argument is underway.

That is another one of those, " It Depends".
In this case on how long you will be gone.
...lew...

You start saving energy as soon at the house temperature stabilizes at
the lower temperature. Except for very short times, when you let the
temperature drop and then immediately ramp it up again, you always save
energy by lowering your house temperature.

Here's what the DOE says about it:

"A common misconception associated with thermostats is that a furnace
works harder than normal to warm the space back to a comfortable
temperature after the thermostat has been set back, resulting in little
or no savings. This misconception has been dispelled by years of research
and numerous studies. The fuel required to reheat a building to a
comfortable temperature is roughly equal to the fuel saved as the
building drops to the lower temperature. You save fuel between the time
that the temperature stabilizes at the lower level and the next time heat
is needed. So, the longer your house remains at the lower temperature,
the more energy you save."

--
Ed Huntress


True. Yet I still hear this type of "reasoning" all the time. Should be a
simple concept even for the technically challenged, for example, people
who argued here that you can compress air and allow it to expand (while
doing no useful work) with no loss of energy.

It's not as simple as a lab experiment in a vacuum jar, though, unless you
put a big rock in the jar to represent thermal mass. g

--
Ed Huntress