"JimmySchmittsLovesChocolateMilk" wrote in message
...
Okay, I'm new to this heat pump stuff,
always lived in the land of the cold where we used gas to make heat!
FIRE!
grunt grunt!!!

so, now I have a nambie pambie heat pump on the house, and today for the
first time or, last night really, it got below freezing,
26 to be precise, well, the heat pump has been running almost
constantly,
and from time to time, the AUX heat has been kicking in too.
is that normal? The air temp outside is 34 right now, and the air comming
out of the vents is 80
About 2 weeks back I had a "disk" replaced, (some type of stat they
said)
temp outside was probably in the 45 -55 range then, but the air comming
out
of the vents was closer to 90,

is this normal??
can the heatpump only give me 80 degrees on days were the temp is at or
below freezing?
the pump is only 5 years old, and at the time the disk was replaced the
pressure was checked and it read high.

thanks for any input


Sounds about right, pnly thing leaves me wondering is the reference to this
"disc"--Oh well, Im not an hvac pro, just that Im fairly familiar with many
aspects of their operation.

As outside temps drop to near freezing, a typical heat pump loses capacity,
quite a bit--though my numbers are off somewhat, think of it kinda like a
42,000btu unit capacity unit only has 21,000 capacity when operating in
these temps. They are still more effecient than straight electric heat as
far as overall energy cost / heat produced, because the compressor amperage
draw drops also--if you cant provide the heat into the outside coils then
the compressor pump runs only partially mechanically loaded.

..PDF document showing performance data for a typical heat pump, the heating
capacities start at around page 12 :

http://www.luxaire.com/PDFFiles/036-...002-A-0104.pdf

Now, If the outside temps never dropped below about 45 degrees where you
live, likely the aux electric heating strips would never come on at
all.......generally, they are optional equipment and arent always even
installed into a unit from the factory.........

Where you will notice the coldest air being discharged from the registers is
probably when the unit goes into "defrost mode"--under cold conditions, ice
will form on the outside coil which blocks airflow........to melt this ice,
the unit automatically temporarily reverses operation and turns itself into
an A/C unit when icing of the coils is sensed, rejecting some heat to the
outside from inside of the house--you can tell when this happens, because
the compressor on the outside unit will be running but the fan outside will
be off......

After a few minutes, the reversing valve click and you will hear the
refrigerant go psssttt as internal pressures reverse, and also the outside
fan will start up again---wah lah, you are back into heating mode
again.......

So, if it werent for them aux electric strips coming on, the air coming out
of your registers would be VERY cold indeed during a defrost cycle

--


SVL