In 1978 my new home included a GE (now Trane) high (for those days)
efficiency heat pump. The home was located 8 miles west of Atlantic
City. NJ had a moratorium on new connections for gas as was in short
supply.

At the time I was taking a job as a generation performance engineer for
the local electric utility. I confirmed (I'm a mechanical engineer
(PE)) the capacity rating of the heat pump vs the heating load
calculation. I also had the company's heat pump engineer check it
also. The heat pump could carry the house down to 15 degrees without
backup heat.

18 years later we moved and sold the house. The original heat pump was
still running well. Total repairs during that 18 year period was
NOTHING.

I suggest that you just confirm what the manufacturer suggests is the
appropriate balance point setting and leave the controls to do their
job.

Low outside temperatures do reduce the COP (coeefficient of
performance) and do reduce the temperature of the air handler output.
Those two items may cause some people to want to use backup heat, but
why try and second guess the manufacturer?



twfsa wrote:
My heat pump run at 17 degs, and then the Natural gas furnace takes over, I
do get a reduced electric rate in the winter because of the heat pump, so I
let it run till it can't keep up. The installer should of set the outside
unit to run down below 30 degs, or to where its not keep you comfortable.

Tom
\

"Home owner" wrote in message
oups.com...
I live in Southern Maryland. This year we had a heat pump installed
with propane backup heat. Early on we were using a lot of propane
because I was turning the heat down to 55 at night. I have rectified
this by setting the heat to 68 when we are home and 66 when we are away
or asleep. Is 2 degrees the most I should fluctuate it on a daily
basis?

Secondly and this is my main question... I have heard that heat pumps
are no longer efficient at 30 degrees. So when I see a stretch of a few
days that are going to be cold, below 30 degrees, should I just turn on
emergency heat? Thus turning off the heat pump for these cold days when
it would be inefficient? Currently it tries until it can't keep up. I
am thinking this time when it trying it is just burning my electricity
and cash. Would this be the most efficient way to heat?