In article , dpb wrote:
Doug Miller wrote:
In article , Wayne Whitney
wrote:
....

Now if you initially set the thermostat to 80 degrees, and then reset
it to 70 degrees, you will initially overshoot your target temperature
by 10 degrees as far as air temperature. But at this point the
average temperature of the materials in the house will be closer to 70
degrees. You will reach equilibrium with everything at 70 degrees
sooner.

No, you won't. Not unless you've discovered some new laws of thermodynamics.

Well, that's a different question -- if the bulk mass were sufficiently
large, that is at least theoretically possible owing to the higher heat
transfer rate potentially possible when the temperature rises past the
previous setpoint.

Won't be much higher -- heat transfer rate is proportional to absolute
temperature. 70F = 294K; 80F = 299.6K; so the difference between heat transfer
rate at 70F and 80F is less than two percent.

However, it would, I think, be unlikely to actually work that way in
real life to a significant extent as the interior surface temperatures
of the objects being heated are still rising the along the same path as
before until air temperature passes the previous setpoint shutoff point
so there still is only a small (if any) increased delta-T to drive the
supposed increased rate at which the bulk material is going to be
warmed--for most cases, that will be limited by the conduction path into
the material.

Exactly.

Overall, think it would still lose on the efficiency side, might in some
particular instances improve personal comfort slightly although it would
still take the same time to reach the initial setpoint anyway, so by
that time a sweater in the interim would probably be far preferable and
cheaper...

:-)

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.