I have had a heat pump (16 seer) 3 years now, and am very satified with
winter utility cost, I live in the midwest and the winters can be brutal. I
have the outside thermostate on the unit set to operate down to 17 degs.
So far this winter the elecrtic bill has been no higher than $75, the n/gas
bill $68. Maybe $5-$10 in past years higher.
I have a set back thermostate, set back to 67 at night, 69 during the day
and 73 in the evening till 10:00 PM.
I received a notice from the electric utility to set it and forget it to
save more $$$.
My house is a ranch, 12 yrs old, 2K sq ft.
Whats your opinion?
I have never understood that philosophy. Following that guideline,
you would also set your air conditioner at one temp and never change
it. Heat pumps and air conditioners are basically the same animal.
The heat pump just has the ability to reverse itself to extract heat
from the air. Our new Trane heat pump came from the factory with a
set-back thermostat. And that's exactly how we use it.
The notice you received was intended for owners of heat pumps with backup
electric resistance heat. With that type, it usually costs more to warm the
house back up in the morning than a person saved the previous night.
Did the notice actually say natural gas backup on it, or was it a generic
type notice that could have been sent to all heat pump owners? Does your
electric utility also deliver natural gas, or do you get that from another
That doesn't make any sense at all. Our heat pump has natural gas for
backup (Dual-fuel, 100K BTUH gas heat.) When it comes on in the
morning, it takes only a few minutes to get the house up to 72 from
65. If we let the heat pump do it by itself when it is 18-degrees F
outside, it would take all morning. I will take a few minutes over a
few hours any time from a cost standpoint for either gas or
electricity. I might understand the suggestion if heat strips were
used for backup, and the cost of electricity per KWH is high in that
location. But surely not for natural gas.
On Sat, 04 Feb 2006 14:41:56 -0700, Dick <LeadWinger> wrote:
If your furnace only takes a few minutes to raise the temperature from
65 to 72 when it is 18 degrees outside then your furnace is grossly
oversized! How do you feel burning all that extra fuel you never
needed and getting those hot and cold blasts of air?
I really doubt that. We don't have hot and cold blasts of air. Our
system performs beautifully. The sizing of the heatpump was done by
an engineer with a masters degree in refrigeration. He is also a West
Point graduate. The dealer he works for has the best reputation in
town. The furnace part of the heat pump and the a/c part are exactly
the same size as we had before in a Day-Night gas pack. 100K heat,
48K cooling. The heat pump just runs far more efficiently than the
old gaspack, and even with the huge increase in energy costs, our
total energy cost is running about $100 less per month than it did
last winter with similar degree days. We live at 5,000 feet where it
snows in the winter and gets over 100F in the summer.
If you have electric resistance heat backup, setback with a properly
sized system will increase your electric bill. This is because you
shut off your cheap heat, the heat pump, at night. Then you do
recovery with the expensive heat in the morning (The resistance heat).
The resistance heat only gives you 1/3 to 1/2 the BTUs per watt that
you get from the heat pump.
If you have gas backup, setback makes much more sense. However, if you
are recovering quickly, your system is oversized. Sounds like your
Master used the 500 Sq. Ft. per ton rule. This is the national average
installed sizing for the last 50 years. They use it from Maine to
Florida. Your "Master in refrigeration" sounds like a hack. If he did
a true load calculation, most likely the size of your equipment would
have been smaller. My 2000 sq ft house in hot humid Myrtle Beach SC
only needs a 2 ton heat pump with 4 KW connected backup resistance heat
to maintain year round comfort. Of course it depends on your
insulation, exposure, weather conditions and amount of glass, but your
system would perform even better if it were sized properly, which I
doubt it is, from the information you provided. Did The "Master Of
Refrigeration" actually show you a degree from a REAL University? The
salesmen around here tell all sorts of lies, which no one ever checks
I would call West Point a "real" university. He was also a Major in
special forces. I didn't see his sheepskin for his master's degree,
but I remember it was a major university, and in my discussion with
him there was no doubt as to his credentials. I think he has been in
HVAC for about 12 years. He is not their salesman, per se, he designs
the systems for their customers.
In that case, either someone at your electric company is seriously
misinformed, or they are deliberately misinforming the public so they can
sell more electric. In the majority of cases, it's definitely cheaper to set
a heat pump back at night if the fuel used to raise the temperature the next
morning is natural gas. You might even try to find a better 'economic
balance point'. Did the installer do a Manual J heat loss calculation and
come up with the 17 degree balance point? If he didn't, then try moving the
balance point up to 30 degrees and see if you save more money.
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