Discussion:
Dealing with an old AC unit
(too old to reply)
bob prohaska
2021-04-16 02:38:40 UTC
Permalink
Pondering what to do about a little-used HVAC unit dating from
the mid-1980's. It worked when I bought the house in 2008,
quietly stopped cooling in about 2015 and even when it worked
was used only a couple times per year, max. I do use the heat
a few months per year and that was successfully fixed for $600
recently. The compressor still runs and draws rated power.

A replacement of the whole thing was quoted at around $9k, in
part (I think) because of mandated duct insulation and sealing
work that's required. Given the sporadic use, I'm not sure the
extra work will pay for itself and access is lousy, so doing a
good job on the ducts will be difficult.

My gut reaction is to start by having the AC system recharged
after leak-checking. There's no reason to think the compressor
is faulty, though of course it's a risk. I'm thinking the leak
check will give some chance to test the compressor.

It's an R22 system, a Rheem/Ruud 4-ton plant on a 1600 sf house.
There are "drop in" R22 replacements, and reclaimed R22 is said
to be available. There's no hint about the quality of either.

I'm a little spooked by folks I know who have been having repeated
evaporator failures on brand-new installations. Thus my instinct
to preserve the existing system even though it's a bit inefficient.
At low usage, efficiency won't pay for many service calls. Annual
heat cost is around $500, cooling will probably be worth about the
same if I use it.

Thanks for reading, and any thoughts.

bob prohaska
Tekkie©
2021-04-16 19:20:06 UTC
Permalink
On Fri, 16 Apr 2021 02:38:40 -0000 (UTC), bob prohaska posted for all of us to
digest...
Post by bob prohaska
Pondering what to do about a little-used HVAC unit dating from
the mid-1980's. It worked when I bought the house in 2008,
quietly stopped cooling in about 2015 and even when it worked
was used only a couple times per year, max. I do use the heat
a few months per year and that was successfully fixed for $600
recently. The compressor still runs and draws rated power.
A replacement of the whole thing was quoted at around $9k, in
part (I think) because of mandated duct insulation and sealing
work that's required. Given the sporadic use, I'm not sure the
extra work will pay for itself and access is lousy, so doing a
good job on the ducts will be difficult.
My gut reaction is to start by having the AC system recharged
after leak-checking. There's no reason to think the compressor
is faulty, though of course it's a risk. I'm thinking the leak
check will give some chance to test the compressor.
It's an R22 system, a Rheem/Ruud 4-ton plant on a 1600 sf house.
There are "drop in" R22 replacements, and reclaimed R22 is said
to be available. There's no hint about the quality of either.
I'm a little spooked by folks I know who have been having repeated
evaporator failures on brand-new installations. Thus my instinct
to preserve the existing system even though it's a bit inefficient.
At low usage, efficiency won't pay for many service calls. Annual
heat cost is around $500, cooling will probably be worth about the
same if I use it.
Thanks for reading, and any thoughts.
bob prohaska
A 40 year old system is past end of life. You could try the leak check but if
it's fixed you are still on borrowed time. IDK what R-22 is going for now but
probably over $125/lb. Fix it this week and it blows again next week. Ask the
neighbors for referrals and get at three quotes. Do not expect a new system to
last 40 years. Good luck and let us know what's happening.
--
Tekkie
bob prohaska
2021-04-18 04:48:34 UTC
Permalink
Post by Tekkie©
A 40 year old system is past end of life.
What!!? I'm shocked 8-)
Post by Tekkie©
You could try the leak check but if
it's fixed you are still on borrowed time.
That much I know...
Post by Tekkie©
IDK what R-22 is going for now but probably over $125/lb. Fix it this
week and it blows again next week.
Or, maybe it runs another ten years..... If I can get another year
for $800 that's the annual cost of a new system, by conventional
wisdom.

What about the "drop in" R22 replacements? I gather new systems come
with refrigerant blends anyway, so I might as well get used to them.
Far as I can tell none are azeotropic.

My hope is that technology will improve in the next few years. Mostly
I'm trying to stall.

Thanks for writing!

bob prohaska
bob prohaska
2021-06-06 01:56:55 UTC
Permalink
Post by bob prohaska
Post by Tekkie©
A 40 year old system is past end of life.
What!!? I'm shocked 8-)
Post by Tekkie©
You could try the leak check but if
it's fixed you are still on borrowed time.
With the move toward non-HFC refrigerants, borrowing some time looks
like a good idea. AFAIK, none of the currently-popular refrigerants
and/or blends meet the new requirements. The leading substitutes
are ammonia and carbon dioxide. Both are established for industrial scale
systems and I gather CO2 is used on some smaller standalaone food service
applications.

Any ideas when we'll know what's happening with the home HVAC market?

Thanks for reading,

bob prohaska
Post by bob prohaska
That much I know...
Post by Tekkie©
IDK what R-22 is going for now but probably over $125/lb. Fix it this
week and it blows again next week.
Or, maybe it runs another ten years..... If I can get another year
for $800 that's the annual cost of a new system, by conventional
wisdom.
What about the "drop in" R22 replacements? I gather new systems come
with refrigerant blends anyway, so I might as well get used to them.
Far as I can tell none are azeotropic.
My hope is that technology will improve in the next few years. Mostly
I'm trying to stall.
Thanks for writing!
bob prohaska
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