On Sun, 13 Feb 2005 08:43:45 -0700, Dick LeadWinger wrote:
On Sat, 12 Feb 2005 23:40:44 GMT, Nick
wrote:
Hi,
I'm just about to bite the bullet and fit whole house A/C.
I already have gas powered water filled radiators but since the cost
of a heat pump is only $250 more than straight A/C I was thinking for
spring/Fall heating (in DC) it might be a good idea.
Never owned a heat pump but the sales guy claims they are just as
efficient at making cold as regular A/C.
Anyone wish to share the pros/cons?
Thanks
Nick..
If you compare SEER to SEER there is no difference in cooling
efficiency. The heat pump is just an air conditioner that can be
reversed to take heat out of the air instead of the opposite.
If you intend to keep your existing heat system, there may be no
compelling reason to get a heat pump until you examine the costs of
electricity and NG where you live. In our case, we heat and cool with
the same unit. Called a gaspack. Electrical A/C combined with NG
forced air heat. We have on order a dual-fuel heat pump which
switches over to natural gas at about 38F. This gives us the best of
both worlds. We can use electricity to heat until it is less
efficient than NG, then it switches over. If I had a separate heat
system as you do, I would have to do a completely different
evaluation.
Dick
Another thought too. In my home, I have oil fired baseboard hot water and
replaced my conventional A/C with a heat pump this winter. Since the HP
becomes my primary heating, I qualify for an electricity discount in my
area (Philly region). The discount is such that after paying for the
electricity for running the heat pump, my total electric bill is barely
higher than it was without the heat pump but paying full electric rates.
So in essence, I get very low cost heating for ~75% of my winter.
One additional piece of information - my heat pump is a geothermal unit.
BUT it was installed in such a (crappy) manner that the efficiency of a
good air source heat pump (2.5) is better any time the temp is ~30 out.
So if you do get electric discounts and your KWh usage is pretty high (my
daily usage runs 60-120KWh), then you'll probably find your total utility
bill to be very favorable when using a HP as much as possible when the
temps are above freezing.
Here's an example. Numbers are based on my typical usage patterns when
temps are in the mid 30's.
non-discounted electric: $0.142/KWh
discounted electric: $0.11/KWh
daily usage before heat pump: 56KWh
usage with HP, 6 hours/day: 80KWh
electric cost, non-discounted: $239
HP cost, discounted: $264
actual cost to heat house using HP: $25.
If I were using oil as my primary heat, I'd still be paying the $239 for
electricity then add on top of that the oil costs and electricity to run
the circulators and burner. For me at current oil costs, this adds
$100+/month under the above conditions (i.e. 30+ degree weather). So,
roughly speaking, I would save $75/month during the winter.
|