Heat pump in question has no emergency heat installed. Location is
Phoenix, AZ.

Is it better to turn it down at night or not. User is on a time of
use plan from Salt River Project. Peak time in winter starts at 5am
but user gets up at 4am and can turn it on then.

Saw this in another group, is it true?

If one has an electric heat pump and is on a time of usage plan with
the power company there are two more considerations.

The power rate goes up at 5am so you are likely to be re-heating with
more expensive power. Also, a heat pump is less efficient as the
outside temperature drops. As it is usually coldest just at dawn,
kickiing the systm on then to re-heat is making it try to work when it
is at it's least efficient state

On Mon, 27 Dec 2004 06:43:09 GMT, someone wrote:

Depends. The typical frame house has relatively little thermal mass
and would save more money being lower for long hours, than it would
cost to heat back up using the incrementally more costly power.

But if you lived in a massive adobe structure and the day rate was 2X
or 3X as high, the answer would be different.

-v.


Reply to NG only - this e.mail address goes to a kill file.

a heat pump is less efficient as the
outside temperature drops. As it is usually coldest just at dawn,
kickiing the systm on then to re-heat is making it try to work when it
is at it's least efficient state

This I know to be true. A heat pump can't cut the musterd at temps
below 40 to 45 degrees. ther just isn't enough heat outside to bring
indoors. This is why emergency heat is installed with an outdoor
tempstat to bring it on uunder those conditions. As to your 1st ? it
well depend on your home constuction and the heat loss of it.