Hi all, My outside AC, compressor unit 3 ton was installed when the house
was built in 1988. It has served me very well for 17 cooling seasons without
any problems. The only maintenance on the unit has been an annual spring
inspection, and it has never needed any parts or freon.
Some say it should have failed three years ago. Others say run it till it
fails. Should I put this machine out to pasture?
Thanks for your input
Vote me for run it till it quits.
There is probably some energy savings to be had but the payback time is not
worth replacing a working system. Just be sure your ductwork is tight and the
system is serviced regularly.
Just imagine how efficient the newer systems will be when yours finally quits
Dunno why some would say it should have failed "three years
ago"; you sure it's not jealousy? <g>
I look at stiff like that a little like a car: Given good
care/maintenance/driving, even years ago it wasn't all that
unusual to get a hund thousand miles on one, and todays
cars, well, I know several who made it real close to two
hundred and the reason they got rid of them didn't have
anyting to do with the mileage - they rusted out, fell
apart, stopped heating, needed a fuel tank, stuff like that.
IMO, I think this way:
-- Will I care if it goes out on a hot day and it takes a
week to get it replaced?
-- If I replace it, is there any assurance the replacement
won't go out during its infant mortality stages and require
a week to fix?
-- How much does it cost to run it per hour of electricity
-- How much does it cost to run a new one per hour of
-- Is the cost of a new unit worth that long a payback
period/the loss of the extra money?
-- Do I care/like/dislike/need/want the neat little bells &
whistles that go with a new unit?
And so on; the list can get longer, but that's my initial
I'm cheap! I don't fix things that ain't broke unless I
have a pressing reason, not because someone else told me I
should. And I'll research the info I need IF I worry about
it giving up soon, rather than take anyone's word for it.
And yes, I'm above average with my preventive maintenance;
saves thousands. Finally retired my 28 year old lawn
tractor two years ago; had to, the mower deck was a sieve
instead of a deck and couldn't be patched anymore, the
battery holder was gone, and the steering was a point 'n'
hope style. Love my new one though! But it ain't gonna
last like the last one, I can see that now. Oh yeah, the
old one's a bird haven; we fill it with cedar in the winter
for the birds.
What is your AC bill , what seer is your unit, they loose apx 2% in
efficiency per year. You could get 14 - 20 seer, depending on where you
live and how much you run it will determine what is best for you. If
your old unit is say a 7 seer a 14 will cut your bill in half. At 14
seer is 1 watt consumed for 14 btu of cooling.
Run the numbers your savings may be worth it, and you will avoid a
Then do you have forced air heat ? consider a 94.5% furnace with VS DC
motor that will save electricity in winter. Now your costs are up and
so are your savings.
Do you have a citation for "loose (sic) 2% in efficiency"? Assuming a
good installation and proper maintenance, what causes the efficiency
loss? If your thinking is that it is leaking compressor valves, then
would this same premise apply to scrolls?
I have a 20 year old Carrier Round (recip) that was originally rated -
with it's oversized evaporator and TXV -at 8.3 SEER. I just measured
the power consumption (including air handler) at 3.6 kw, which for 30K
BTU would be a SEER of 8.29.
Admittedly, I don't have an accurate way to measure the total BTU output
of the system, but temperatures and pressures are spot on relative to
the day it was installed. If the 2% efficiency decline were correct
then I'd expect the performance change and or electrical consumption
difference to be significant, and therefore noticeable.
Also, I recently replaced a second, identical Carrier system with a 29K
BTU 13.0 SEER unit, and received exactly the cost reduction I expected
to see by going from 8.3 SEER to 13.0 - power consumption went from 3.6
kw to 2.2 kw and my power consumption (adjusted for degree days) dropped
accordingly. Again, no sign that the old system performance was
degraded 40% by "age".
The average lifespan of a 1980's split system air conditioner is about
15 years. Yours is just at the average point, which means it could
easily run longer. However, it is remarkable that you've never needed
any service. Usually you'd have replaced at least the condenser fan
motor by now, and maybe a capacitor or two. Both these are minor
I would let the system run, and even consider repairing it a couple of
times (assuming you don't spring a refrigerant leak or have something
else happen that requires opening the system). Installed in 1988, your
current system is probably a minimum of 9.0 SEER even if it was a
"builder's model". Although new systems will be more energy efficient,
you'll never pay back the investment required to replace a functioning
system with energy cost reductions.
| Hi all, My outside AC, compressor unit 3 ton was installed when the house
| was built in 1988. It has served me very well for 17 cooling seasons
| any problems. The only maintenance on the unit has been an annual spring
| inspection, and it has never needed any parts or freon.
| Some say it should have failed three years ago. Others say run it till it
| fails. Should I put this machine out to pasture?
| Thanks for your input
When I moved into my current home I had the furnace and AC checked by a
"professional" and he strongly suggested I replace them as he assured me
they were old and couldn't possibly last much longer. That was 15
heating&cooling seasons ago and they're still going strong. If it ain't
broke don't fix it.
It is not possible to say how much longer it may continue to function.
It is easy to say that you will save operating cost using a new one. The
question is will it be worth the cost to get the savings. In some parts of
the world you may have cheap power and only run it a few weeks a year. In
other parts power is far more expensive and you may run it all but a few
This is Turtle.
I'm sorry to tell you that by a accident or on purpose some hvac installer
installed your system correctly. If by accident a installer installed it
correctly. you are faced with the problem of it running the next 30 to 40 years.
Now you will have to change the condenser and furnace blower motors before the
40 years is up but You will be doing a good deed by letting a hvac service
company make a little money.
30 to 40 years is not out of the question if installed correctly and oil the
blower and condenser motors every 20 years weither they need it or not.
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