"Joseph Meehan" wrote in message
...
Larry Sue wrote:
It's just above 0 F and my heat pump is working almost non-stop. Is
it more economical to turn electric heat strips and leave the outside
unit off? I'd appreciate any advice.

Thanks.

It will decide for you. When it can not provide enough total heat
the
resistance heat will kick in. I would assume, which is always a bad thing
to
do, any well designed system would shut down the heat pump part when the
temperature was so low as to be come less than 100% efficient. Sorry I
really don't know if they do or not. If not, they need better engineers.


Only if its a programmable ( smart ) thermostat will it will fire the aux
heat strips automatically, otherwise this same terminal on the air handler
will also ( usually ) be tied in with a signal from the heat pump condensor
in order to activate the aux heat strips whenever the heat pump goes into a
defrost cycle.

Some systems will also ( but not always, by any means ) have an outdoor
thermostat (as an option ) that will lock out the heat pump altogether once
the outdoor temp gets below some set point so that on a call for condensor
startup the signal will be bypassed and will instead energize the aux heat
strips .

It all depends on the unit and the installer and the decisions that were
made by both when it was purchased and placed into service.

Doubtful anyone is likely to go through the tedium to determine which might
be the actual case over the internet--especially when we dont even know if
the OP owns a meter or knows how to read the schematics for the unit in
question.

Suffice it to say if the unit runs constantly, letting it run is probly the
most energy efficient thing to do, and then if the house still gets too
cold, turn on the aux heat also--but do realize this will make for a rather
largish utility bill.

--

SVL