Thanks for the recommendation of the chart.
It is hard for me to trust HVAC people on such matters. Last year my
parents got new units for two houses. One has two stories, six
bedrooms, 5.5 baths, and seven other rooms and they sized it at 2
tons. Now the inside of their house is mildewing because it can't
keep it cool or dry. The other house is one small story, three
bedrooms, two baths, 2 other rooms, and they (different person) sized
it at 4 tons. I told my parents that, if anything, they should have
put the 4 ton unit in the big house and the 2 ton unit in the small
If that pump has been running well, it has few more years life left.
B4 you decide to spend for upgrading, how about air
tightness(insulation) of your house? SEER 10.5 is of course outdated to
today's standard but to get real improvement you have to deal with whole
package, not only one component of a system.(like air handler, etc.)
What is your electric rate? I pay 7 cents/KWh.
It varies according to the season and according to how much you use.
It is higher in the summer. The first 1000 kWh are one rate, then it
goes up. Then it goes up again at 2500 or something like that. I
think the top rate is over 10 cents / kWh and we hit that in the
I see. I live up here in Calgary Alberta. For next 5 years my rate is
locked in at 7 cents per KWh. If ever rate drops(most unlikely) I can
cancel the deal any time with two months notice. Right now going rate
is 11 cents.
A real estate agent is in no way, shape, form or fashion qualified to
say if a heat pump is oversized. call a licensed hvac contractor and
have the m do a manual J load calculation. That is the ONLY way you
will know for sure.
I'm not an a/c person, but as a home owner, just had recent
Our 11 year old A/C - heat pump went out and we had it replaced;
the outside unit, the air handler in the attic, and larger return
air vent pipe. (We had 16 inch and the A/C people recommended 18
inch). All in all the whole thing was $7,300. Our next month
electric bill was less by $80.00. There could be other factors
involved in that as well, but no doubt it was cheaper.
It would take a very long time to pay for the new unit with the
savings, so if that is why you are considering it, I doubt it would
One more thing, there are two types of Freon units. (I forget the
numbers). The old type is going to be discontinued in a couple
years and the price will sky rocket like the old style auto Freon.
I'd suggest that if you get a new unit that you get the new Freon
Like old R22 vs R410a something like that? Carrier calls it Puron.
R22 equipment won't be made after 3 years from now and R22 production
will diminish slowly in next 30 years or so I heard. Our a/c runs on
If his total yearly estimated electric bill for his heat pump to heat
and cool his house is only around $1000, I think it's very unlikely
he's going to save enough in electricity to justify getting a new
higher efficiency unit.
This is for cooling only, but you can approximate the heating.
Maybe, need a load study by a qualified HVAC person.
You used nothing in November? where do you live, Key West.
I was faced with the decision about 18 months ago when the compressor
in my 16 year old unit went out. New compressor or new unit. HVAC
guy talked me into new unit. Said savings would be significant. I'm
glad I listened to him. I'm all electric and have a 5 ton packaged
unit and my total usage went down by approximately 20%. I've never
had an August as hot as '07 (20 days over 100F, most lows high 70's
to low 80's) and my bill was $192. The previous five Augusts averaged
about $250. Plus the new unit is far more quiet.
I went from an estimated 7 SEER (I guess that long ago they were not
labeled), to a 13 SEER
If you are in the U. S. and pay taxes, you should also go on the gov.
energy site and look up the potential tax credits. I believe it is
$300 for a heat pump that meets the SEER and EER, and the standard for
the heat side, requirements.
In my case the difference between a new compressor and a new unit was
$3K. I couldn't qualify for the tax credit, because, low and behold,
there was no "packaged" unit in existence that met the Govs standards
on the heat side. But there were plenty of splits which are more
common. You can get a split up to 19 SEER. I figure I'm saving about
$4-500 per year. So six years or so simple payback without the tax
If you read carefully I said "simple" payback, not payback based on
discounted cash flow or present value analysis.
So are you suggesting that at the decision point of whether to sink
$1000 into a sixteen year old, inefficient heat pump that would
require maintenance money put into it each year despite the new
compressor, that I should have considered that a reasonable
alternative? Maintenance money combined with unit inflation till the
time when it would have to be replaced anyway which would be far in
excess of the interest earned on the savings? True discounted cash
flow considers both the timing and amount of both outlays and income.
If you assign risk appropriately and run all the numbers, the decision
is a no brainer
On the facts you presented, you would have had a new compressor.
It's not clear to me why you assume maintenance would be so high.
But my point was just that "simple payback" doesn't tell the
whole picture -- if you actually did the full analysis, then
good for you.
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