On 18 Dec 2004 10:57:16 GMT, otforme (Charlie Self)
wrote:
[snip]

And maybe I'm getting screwed. Hard to tell. I was told that when the air is
much below freezing, heat pump efficiency drops dramatically. I'll have to dig
out some information on the thing, as we seldom get down to 10 degrees here, so
a setting of, say, 20 or so if it is reasonably efficient, might prove a money
saver when the guy in the rolling propane bottle pops down the drive.

Charlie, I did a temp plot last night of the heat pump. It started to
lose ground at about 10 deg. About 30 minutes later it switched over
to the propane furnace. We had 9 below last night. At 20 degrees
your pump should be happy. The manual for mine specs down to 0 for
outside operating temp. Also the measured power on ours is about
2200 watts. So it only costs about 7 cents per hour of run time.
--
John, in Minnesota