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Default All aluminum versus copper/aluminum coils for air conditioner?

On Saturday, March 31, 2012 at 5:47:00 AM UTC-7, Smarty wrote:
I have spoken with several HVAC contractors regarding replacement of my
old Lennox central air conditioning system. All of them are Lennox
dealers except one who also carries Trane products.

The dealer who also carries Trane was trying to switch me from my
original Lennox preference, stating that the Trane coils, which are 100%
aluminum, rather than the Lennox coils, which use aluminum fins and
copper tubing, provide a better, longer lasting design.

He felt that Trane was superior in other ways also, since they used
"composite plastics" in the outdoor condensing unit case rather than
steel to ensure that no corrosion or rusting would occur.

The basic claim was that Trane, using aluminum for all of the
refrigeration loop, had a longer life expectancy that Lennox, given the
newer Puron refrigerant.

Does anyone have any experience with Trane, and is there any science to
support this type of claim or any other prior experience to say that
Trane is somehow better?

Thanks for any advice.


I've worked in the HVAC trade and would like to share some up-to-date facts about copper

versus aluminum condensing units and evaporator coils.

First, let me separate all A/C coils with fins from coils with all-aluminum spines known as

'Spine-Fin' made by Trane and sold by Trane and related companies, used in outdoor condensing

units and heat pumps. I recommend against products the use the spine-fin design. This design is notorious for plugging up, loading up with cottonwood fluff, spider silk, leaf litter, insect debris etc. Regular visits from the service man are necessary to burn the debris out of the coil with a torch since washing with the powerful spray cleaners normally employed in coil cleaning are ineffective on spine-fin coils.



Copper tube coils with aluminum fins versus all-aluminum tube coils with aluminum fins...


1a) Money - Copper prices went out of control high when the Chinese economy boomed prior to the Great Recession of 2008. It only reasonable for U.S. manufacturers to anticipate future copper metal price spikes in considering potential future cost and potential copper shortages. Aluminum metal is plentiful, but uses a great deal of electrical energy to refine the ore.

Advantage aluminum.


1b) Aside from the cost of copper metal, aluminum coils are more difficult and costly to manufacture. This is in large measure because it is difficult to join aluminum tubes because of the thin layer of oxide that forms on aluminum. Copper is much easier to join and repair. New aluminum soldering alloys were developed over recent years that have improved the process of producing all-aluminum coils, although it is still remains difficult to repair an aluminum coil in the field.

Advantage copper.


2) Higher refrigerant pressures - New EPA mandated chlorine-free refrigerants replaced long time standard HCFC refrigerant R-22 in 2012. An example of a new refrigerant is Carrier's Puron (which is known in the trade as R-410a) which operates at higher pressure than R-22, so the tubing used in making new condensing and evaporator coils must have thicker walls to resist the higher pressure.

The new refrigerants heat-carrying ability, known as its enthalpy, fluid ounce for ounce, is less than that of R-22. Combined with other physical properties, greater mass flow is needed to move the same quantity of heat, thus larger coils are needed. Larger coils mean more metal used. A-coils in evaporators (at the furnace end) become N-coils to absorb the heat from the air stream, and condensers (found outdoors to move the heat into the air) must be much larger to handle double the flow of refrigerant. EPA also mandated higher Seasonal Energy Efficiency Ratios (SEER) for air conditioners and heat pumps, requiring these coils to be made larger still.

Advantage aluminum.


4) Corrosion - Copper coils are made with aluminum fins mounted in galvanized steel frames, which is a recipe for galvanic corrosion over time. Aluminum metal reacts with the oxygen in the air to produce a thin, but tough oxide coating that protects the underlying metal from corrosion. If the aluminum metal is scratched or scuffed, the protective oxide layer reforms almost immediately. Aluminum coils are all aluminum, and being homogeneous, do not suffer from galvanic corrosion the way three-metal copper coils do. But the protection afforded by the oxide layer is not absolute; Aluminum is very sensitive to chloride corrosion from animal urine, like dogs sent marking or male cats spraying, sea salt spray, etc. While chloride will destroy both copper and aluminum coils, chloride attacks aluminum coils much more aggressively.

Advantage aluminum, except by the ocean.


4a) Chinese Drywall, More Corrosion - References are made in this thread to Formicary Corrosion a.k.a. Ant Nest Corrosion. Formic acid is an organic acid produced by ants to signal each other, but many organic acids can cause this deep pitting corrosion in copper. Some thread entries blame ants, but not one entry has named the actual cause behind most of the recent spate of damage to U.S. HVAC equipment - hydrogen sulfide off-gassed by impurities in imported Chinese drywall. Because of its protective oxide layer, aluminum does not react with hydrogen sulfide the way copper does.

Advantage aluminum.


5) Field serviceability - Repairing aluminum refrigeration tubing is much more challenging than repairing copper tubing. Copper can be heated all the way to cherry red glow without damage. It can be both brazed (temperature over 800 degrees F) or soldered (temperature below 800 degrees F). Aluminum heats up and as the temperature rises, without warning, melts onto a puddle.. When the temperature is tightly controlled, because of that thin, but tenacious layer of aluminum oxide mentioned earlier, solder or braze filler metal alloys have difficulty bonding to aluminum. Recently developed exotic and expensive fluxes are making field repair easier, but some technicians still refuse to even attempt a field repair on an aluminum coil, insisting on replacing it instead.

Advantage copper.


Conclusion.

I think it is fair to say the future is all aluminum coils, both because of the cost savings in the less expensive metal, and continuing improvements in aluminum joining and repair techniques.

Aluminum or copper, to stretch the life of your investment in A/C equipment, consider this: if you would like your new A/C or heat pump to last as long as possible, for a few hundred dollars extra, ask your contractor if the brand and model they are offering is available with a 'Coastal' or 'Sea-Side' option. Units with this option are made with their coils coated with a very thin, but
completely corrosion resistant polymer; they are assembled using stainless steel screws and bolts, and are painted with an extra durable paint. Coastal option units are intended for use near the bodies of salt water, but are equally good at resisting corrosion caused by a range urban threats from acid raid to cat pee and many other chemical insults I can't name.


I hope all the above has proven useful at shedding light on the advantages and disadvantages of aluminum and copper coils.
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Default All aluminum versus copper/aluminum coils for air conditioner?

On Saturday, March 31, 2012 at 5:47:00 AM UTC-7, Smarty wrote:
I have spoken with several HVAC contractors regarding replacement of my
old Lennox central air conditioning system. All of them are Lennox
dealers except one who also carries Trane products.

The dealer who also carries Trane was trying to switch me from my
original Lennox preference, stating that the Trane coils, which are 100%
aluminum, rather than the Lennox coils, which use aluminum fins and
copper tubing, provide a better, longer lasting design.

He felt that Trane was superior in other ways also, since they used
"composite plastics" in the outdoor condensing unit case rather than
steel to ensure that no corrosion or rusting would occur.

The basic claim was that Trane, using aluminum for all of the
refrigeration loop, had a longer life expectancy that Lennox, given the
newer Puron refrigerant.

Does anyone have any experience with Trane, and is there any science to
support this type of claim or any other prior experience to say that
Trane is somehow better?

Thanks for any advice.



I've worked in the HVAC trade and would like to share some up-to-date facts about copper versus aluminum condensing units and evaporator coils.

First, let me separate all A/C coils with fins from coils with all-aluminum spines known as 'Spine-Fin' made by Trane and sold by Trane and related companies, used in outdoor condensing units and heat pumps. I recommend against products that use the spine-fin design. This design is notorious for plugging up; loading up with cottonwood fluff, spider silk, leaf litter, insect debris etc. Regular visits from the service man are a necessity to burn the debris out of the coil with a torch since washing with the powerful spray cleaners normally employed in coil cleaning is ineffective on spine-fin coils.



Copper tube coils with aluminum fins versus all-aluminum tube coils with aluminum fins...


1a) Money - Copper prices went out of control high when the Chinese economy boomed prior to the Great Recession of 2008. It only reasonable for U.S. manufacturers to anticipate future copper metal price spikes in considering potential future cost and potential copper shortages. Aluminum metal is plentiful, but uses a great deal of electrical energy to refine the ore.

Advantage aluminum.


1b) Aside from the cost of copper metal, aluminum coils are more difficult and costly to manufacture. This is in large measure because it is difficult to join aluminum tubes because of the thin layer of oxide that forms on aluminum. Copper is much easier to join and repair. New aluminum soldering alloys were developed over recent years that have improved the process of producing all-aluminum coils, although it is still remains difficult to repair an aluminum coil in the field.

Advantage copper.


2) Higher refrigerant pressures - New EPA mandated chlorine-free refrigerants replaced long time standard HCFC refrigerant R-22 in 2012. An example of a new refrigerant is Carrier's Puron (which is known in the trade as R-410a) which operates at higher pressure than R-22, so the tubing used in making new condensing and evaporator coils must have thicker walls to resist the higher pressure.

The new refrigerants heat-carrying ability, known as its enthalpy, fluid ounce for ounce, is less than that of R-22. Combined with other physical properties, greater mass flow is needed to move the same quantity of heat, thus larger coils are needed. Larger coils mean more metal used. A-coils in evaporators (at the furnace end) become N-coils to absorb the heat from the air stream, and condensers (found outdoors to move the heat into the air) must be much larger to handle double the flow of refrigerant. EPA also mandated higher Seasonal Energy Efficiency Ratios (SEER) for air conditioners and heat pumps, requiring these coils to be made larger still.

Advantage aluminum.


4) Corrosion - Copper coils are made with aluminum fins mounted in galvanized steel frames, which is a recipe for galvanic corrosion over time. Aluminum metal reacts with the oxygen in the air to produce a thin, but tough oxide coating that protects the underlying metal from corrosion. If the aluminum metal is scratched or scuffed, the protective oxide layer reforms almost immediately. Aluminum coils are all aluminum, and being homogeneous, do not suffer from galvanic corrosion the way three-metal copper coils do. But the protection afforded by the oxide layer is not absolute; Aluminum is very sensitive to chloride corrosion from animal urine, like dogs sent marking or male cats spraying, sea salt spray, etc. While chloride will destroy both copper and aluminum coils, chloride attacks aluminum coils much more aggressively.

Advantage aluminum, except by the ocean.


4a) Chinese Drywall, More Corrosion - References are made in this thread to Formicary Corrosion a.k.a. Ant Nest Corrosion. Formic acid is an organic acid produced by ants to signal each other, but many organic acids can cause this deep pitting corrosion in copper. Some thread entries blame ants, but not one entry has named the actual cause behind most of the recent spate of damage to U.S. HVAC equipment - hydrogen sulfide off-gassed by impurities in imported Chinese drywall. Because of its protective oxide layer, aluminum does not react with hydrogen sulfide the way copper does.

Advantage aluminum.


5) Field serviceability - Repairing aluminum refrigeration tubing is much more challenging than repairing copper tubing. Copper can be heated all the way to cherry red glow without damage. It can be both brazed (temperature over 800 degrees F) or soldered (temperature below 800 degrees F). Aluminum heats up and as the temperature rises, without warning, melts onto a puddle.. When the temperature is tightly controlled, because of that thin, but tenacious layer of aluminum oxide mentioned earlier, solder or braze filler metal alloys have difficulty bonding to aluminum. Recently developed exotic and expensive fluxes are making field repair easier, but some technicians still refuse to even attempt a field repair on an aluminum coil, insisting on replacing it instead.

Advantage copper.


Conclusion.

I think it is fair to say the future is all aluminum coils, both because of the cost savings in the less expensive metal, and continuing improvements in aluminum joining and repair techniques.

Aluminum or copper, to stretch the life of your investment in A/C equipment, consider this: if you would like your new A/C or heat pump to last as long as possible, for a few hundred dollars extra, ask your contractor if the brand and model they are offering is available with a 'Coastal' or 'Sea-Side' option. Units with this option are made with their coils coated with a very thin, but
completely corrosion resistant polymer; they are assembled using stainless steel screws and bolts, and are painted with an extra durable paint. Coastal option units are intended for use near the bodies of salt water, but are equally good at resisting corrosion caused by a range urban threats from acid raid to cat pee and many other chemical insults I can't name.


I hope all the above has proven useful at shedding light on the advantages and disadvantages of aluminum and copper coils.






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Default All aluminum versus copper/aluminum coils for air conditioner?

replying to Smarty, BobsYourUncle wrote:
Consumer Reports seems to be silent on the whole matter of central A/C

reliability.
This may have been true in 2012 but no longer is:
http://web.consumerreports.org/airco...FQEpaQodqHQFSQ

--
for full context, visit https://www.homeownershub.com/mainte...ne-690615-.htm


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Default All aluminum versus copper/aluminum coils for air conditioner?

replying to makolber, BobsYourUncle wrote:
This will dry your evaporator coils all right, but it will also increase the
humidity inside the house by as much as 10% as well as increase your energy
usage. The evaporator coils that produce water condensation are inside the
house, and are designed to both withstand and shed water, so water on them is
not an issue. What we're talking about here are the condenser coils in the
*outside* unit, which despite the name do not form water condensation, they
condense the refrigerant in the lines back to a liquid which then makes the
coils hot. The only water on the condenser coils comes in externally;
rain/snow, sprinklers, etc.

So from a water perspective, the inside evaporator condenses water and the
outside condenser evaporates it.


--
for full context, visit https://www.homeownershub.com/mainte...ne-690615-.htm


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Default All aluminum versus copper/aluminum coils for air conditioner?

replying to mangino, BobsYourUncle wrote:
He said that Carrier knows that there are issues with the coils rusting out

prematurely. Carrier use to have all aluminum coils and aluminum never rusts.
Carrier and other manufacturers realized if they switched to copper coils their
customers would have to replace their coils approximately every 6 to 8 years (10
years if you were lucky)
Well, it's too late for mangino at this point, but his a/c guy was at least
woefully uninformed on the topic, and nearly everything he said about copper
applies to aluminum as well; in some cases more so. For one, aluminum most
definitely oxidizes as does copper. Your aluminum coils have to be mated at
some point to the copper supply lines, and this is where most of the failures
occur due to the galvanic action of the two disparate metals. Also, the only
good all-aluminum coils were made by GE until they got out of the HVAC
business. The rest are much thinner and consequently cheaper than the copper.
But wait, if you get a leak in that aluminum line (a good possibility, since
aluminum is thinner, weaker, harder to clean, and easier to damage, not to
mention having worse heat transfer characteristics) good luck finding anyone
who can repair it. "Be better to just replace it" is what an honest totally
trustworthy A/C guy would tell you in that situation. Sounds like planned
obsolescence to me...

--
for full context, visit https://www.homeownershub.com/mainte...ne-690615-.htm




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Default All aluminum versus copper/aluminum coils for air conditioner?

replying to bob haller, BobsYourUncle wrote:
Also Amana which is basically a fancy Goodman, much as Lexus is to Toyota;
same manufacturer, just more bells and whistles (but without the extreme price
delta that the autos have).


--
for full context, visit https://www.homeownershub.com/mainte...ne-690615-.htm


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Default All aluminum versus copper/aluminum coils for air conditioner?

replying to mangino, BobsYourUncle wrote:
These are details you won't get from your air conditioning company.

I love that your post makes this claim, then to support it you post a link to
document from Carrier, the very company that your air conditioning guy whom
you totally trust said was going back to copper so it would fail faster.

--
for full context, visit https://www.homeownershub.com/mainte...ne-690615-.htm


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Default All aluminum versus copper/aluminum coils for air conditioner?

replying to DCB, BobsYourUncle wrote:
Neither metal technically rusts; only iron does, but they all oxidize. We just
call ferrous oxide "rust."

--
for full context, visit https://www.homeownershub.com/mainte...ne-690615-.htm


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Default All aluminum versus copper/aluminum coils for air conditioner?

I read this article on www.copperindia.org/thinkcopper
..i found it very interesting on they explained the difference between copper and aluminum ac. I feel this website should solve yr problem


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