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!
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
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
A heat pump runs most efficiently when the output is as cold as possible
while still heating the house, so the air coming out of the registers
should feel cold. If you measure its temp, it's warmer than the room.
That's what you need.
The airflow is kept very high to achieve this - essentially cooling
the indoor coil with indoor air so it never gets hot.
As the outdoor air temp drops, the heat pump does less and less work,
and achieves less and less heating; at the same time, the cost to
run it drops, so in effect you fall back on resistive heating without
any loss of money. In the circumstance where the heat pump no longer
holds the house, it will run continuously (not achieving much) while
the resistive strips kick in and out.
If the heat pump is broken in some way, say constant defrosting,
then this continuous running costs you money. If not, then it's
just the way heat pumps are.
Women like warm toasty air coming out of the ducts. Heat pumps
don't do that. Guys see the method in it and put up with it.
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 :
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
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
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
I challenge the concept of an heat pump where it gets below freezing. Heat
pump reverses the indoor coil and outdoor coil for heating. It is trying to
get heat from the outdoors and put it in the home. Not much latent heat at
26 degrees, so that tells me your aux heat, probably an electric element is
running. Picture a big toaster in the air handler. Lots of them are
installed all over. Gonna cost ya big time if it stays cold like that very
Rest of the operation described seems ok to me.
On Thu, 2 Dec 2004 10:02:20 -0500, "JimmySchmittsLovesChocolateMilk"
Sure sounds like it. We used to have a heat pump; got tired of
listening to it run all the time for little effect, so after it broke
a second time in two years, went with Propane (all we can get out
here). I love the peace and quiet.
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