All aluminum versus copper/aluminum coils for air conditioner?

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On 4/19/2015 9:10 AM, trader_4 wrote:

Things have probably changes since I worked for a company that made coils. Back then, they were copper and full aluminum was just starting to be made by a couple of companies. The only reason they changed was cost.
We had been making copper coils for many years and it would have been costly to change over with all the equipment involved and we did not make large quantities of a given size like Carrier. We did specialties from 6" x 6" to 4' x 20' For tubing we used copper, brass, cupro-nickle
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replying to trader_4 , mangino wrote:

Yes there is another valid reason for the switch to aluminum (in addition to planned obsolence) and it's called Formicary Corrosion. You can get the FACTS by reading the industry research report containing scientific studies and analysis going into the details of aluminum versus copper. These are details you won't get from your air conditioning company.
Here's the link : http://www.conditionedairsolutions.com/wp-content/uploads/2012/04/01-811-20345-25.pdf
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On 4/19/2015 12:44 PM, mangino wrote:

While I found the link interesting, how do you expect us to continue a discussion when you mess up a lot of good arguments with FACTS?
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On Sunday, April 19, 2015 at 4:21:47 PM UTC-4, Ed Pawlowski wrote:

The facts here would seem to be that the document he just provided is exactly opposite to what he's claiming. He stated that Carrier allegedly switched to copper coils from aluminum so that they would fail faster. Yet the document says Carrier is using aluminum coils because they are corrosion resistant and superior. I don't see them saying they went back to copper..... So, I don't see what all the fuss is about.
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I am sure that there are enough posters here to sustain *any* argument, with or without facts.
When I saw the word formicary (formica means ant in Italian) I decided to go look it up to see if it was related to ants (or Formica - which people tell me stands for "FORmerly MICArta). This is another site that describes the problem and claims it can occur within two months after manufacture.
http://www.microchannelfacts.com/formicary-corrosion
<<Formicary corrosion is a type of corrosion also referred to by HVAC contractors as "ant's nest" corrosion.>>
They say it can't be seen with the naked eye but I assume if any kind of corrosion gets bad enough, it will become visible to normal vision.
Learn something new every day!
--
Bobby G.



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replying to Robert Green , DCB wrote:

http://www.conditionedairsolutions.com/wp-content/uploads/2012/04/01-811-20345-25.pdf

Formicary Corrosion can never been seen, it is the very definition of the pin hole mesh; It is rare and is usually caused internally not externally with the introduction of a acidic contaminant in the system.
Copper is tried an true, lasts for decades, provides 2X the heat exchange. (it is the reason that ALL computer CPU cooling is COPPER)
Aluminum is cheaper and easier to bend; which is important because the MFG's have to come up with creative solutions to make up for the reduced heat transfer.
Additionally, copper is easier to repair and unless the Aluminum system does not have copper anywhere it is more likely to see corrosion where Aluminum touches copper then copper has of Formicary Corrosion
Cheers
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On Thu, 23 Jul 2015 23:44:01 +0000, DCB

You'd be surprized how many CPU heat sinks have absolutely NO copper in them. I've even got a pile of them tat a magnet will stick to - not very well, being stainless steel of all things (very poor thermal conductivity, but goot thermal mass - with heat pipes to stainless steel fins, plus folded fins that appear to be aluminum (definitely not copper) fused to the stainless plate.
These all came from P4 and Core Duo equipped Lenovo desktop units.
Most of the rest of my stask are extruded aliminum -I had a couple copper ones from ancient Dell PCs (Inspiron 2400??)

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On Thu, 23 Jul 2015 21:00:23 -0400, snipped-for-privacy@snyder.on.ca wrote:

I have a huge box of heat sinks from computers that date back to the 60s through P4 class machines and they are all aluminum. The only copper I have ever seen is in a WYSE "thin client" machine and it is a short 6 gauge copper wire that connects the aluminum CPU heat sink to a much larger aluminum heat sink next to it.
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<stuff snipped>

I've got a bunch of heat sinks/cooling fans for CPUs and some of them did have a highly polished copper insert that sat right on the chip (with thermal gunk - amazing how much of a difference that stuff makes!)
But by and large they were mostly huge junks of aluminum. There were also sinks that had a bracket that allowed use of a slower, quieter (and harder to plug with dirt) 80cm cooling fan suspended over the CPU. I bought a lot of spares and then switched almost exclusively to tablet PC's I got from Ebay. )-: Not sure what to do with all those spares and for that matter all the SCSI cards, 10Mb NICs, Archive tape controllers (a whopping 250Mb of backup tape - huge for its time), old modem cards, ISA controllers, EISA controllers, SCSI cables (I, II and III) and a host of other stuff from days gone by. Did I mention my wife says I am a hoarder?
(-:
--
Bobby G.






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On Fri, 24 Jul 2015 09:56:58 -0400, "Robert Green"

I just got rid of my last few PS/2 machines recently ;-) I still have a Convertible and a 5150.
My computer room was a fairly good sized bedroom and it is stuffed
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On Fri, 24 Jul 2015 09:56:58 -0400, "Robert Green"

ago!!!!!
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On Fri, 24 Jul 2015 13:18:04 -0400, snipped-for-privacy@snyder.on.ca wrote:

I still have a stack of SCSI drives. I should plug them in and see what I was doing way back in the 20th century. A couple date from the day I retired in 1996 and have not spun since. These are the old technology drives and I bet they will still work.
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On Fri, 24 Jul 2015 13:44:11 -0400, snipped-for-privacy@aol.com wrote:

drivers for the current OS, or a compatible SCSI controller for your computer.
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On Fri, 24 Jul 2015 14:54:21 -0400, snipped-for-privacy@snyder.on.ca wrote:

I am running a SCSI scanner on my W98 Fax/print server. Plug and play.
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replying to Robert Green , DCB wrote:

If you cut them open you will find that any decent heat sink for high speed processors all have copper heat tubes and copper exchangers. They can have aluminum fins but the heat exchange is copper, why? because copper has 2x the thermal exchange of aluminum.
Also I find it interesting that the Carrier article is about evaporator coils not condenser coils, yet its the condenser coils that are being changed to aluminum while almost all of the evaporator coils remain copper.
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On Sat, 25 Jul 2015 03:44:01 +0000, DCB

they are a lot easier to braze and solder than aluminum)
I DO have a copper aftermarket heat sink I forgot about - and even IT has a stainless steel thermal mass plate into which the4 heat pipes are fitted. It's a "ZeroTherm" BTF95 (Butterfly) passive unit (no fan) and also has a copper "transfer pad".
These tend to be used by the same geeks that buy "oxygen free" copper speaker cables. The reviews tend to re-enforce my opinion - They dont cool worth squat. (at $60 MSRP it does not outperform the OEM intel aluminum heat sink)

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replying to mangino , DCB wrote:

http://www.conditionedairsolutions.com/wp-content/uploads/2012/04/01-811-20345-25.pdf
So Silly, one it is difficulty to diagnose, two less that 10% of all AC systems have been affected by Formicary Corrosion; and it is usually caused by contaminants in the "sealed" system.
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replying to mangino , DCB wrote:

LOL Copper does not RUST.... Hilarious
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Avoid Trane as their outdoor condensing unit coils are made using a unique design called 'Spine-Fin' and are notorious for loading up with cottonwood fluff, spider silk, etc.
I have worked in the HVAC trade and would like to share some up-to-date fac ts about copper versus aluminum condensing units and evaporator coils.
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. m anufacturers to anticipate future copper metal price spikes in considering potential future cost and potential copper shortages. Aluminum metal is ple ntiful, 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 al uminum. Copper is much easier to join and repair. New aluminum soldering al loys were developed over recent years that have improved the process of pro ducing 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 refrigeran ts 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-410 a) which operates at higher pressure than R-22, so the tubing used in makin g 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 ou nce for ounce, is about half that of R-22. Since about twice the mass flow is needed to move the same quantity of heat, larger coils are needed. Large r coils mean more metal used. A-coils in evaporators (at the furnace end) b ecome 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 doub le the flow of refrigerant. EPA also mandated higher Seasonal Energy Efficiency Ratios for air conditioners and heat pumps, requiring these coils to be made large r still.
Advantage aluminum.
4) Corrosion - Copper coils are made with aluminum fins mounted in galvaniz ed steel frames, which is a recipe for galvanic corrosion over time. Alumin um metal reacts with the oxygen in the air to produce a thin, but tough oxi de coating that protects the underlying metal from corrosion. If the alumin um metal is scratched or scuffed, the protective oxide layer reforms immedi ately. Aluminum coils are all aluminum, and being homogeneous, do not suffe r from galvanic corrosion the way three-metal copper coils do. The protecti on afforded by the oxide layer is not absolute; animal urine, like dogs sen t marking or male cats spraying, and sea salt spray will destroy both coppe r and aluminum coils.
Advantage aluminum.
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 a cid produced by ants to signal each other, but many organic acids will caus e this deep pitting corrosion in copper. Some thread entries blame ants, bu t not one entry has named the actual cause of most of the recent spate of d amage 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 m ore challenging than repairing copper tubing. Copper can be heated all the way to cherry red glow without damage. It can be both brazed (temperature o ver 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 ten acious layer of aluminum oxide mentioned earlier, solder or braze filler me tal alloys have difficulty bonding to aluminum. Recently developed exotic a nd expensive fluxes are making field repair easier, but some technicians st ill refuse to even attempt a field repair on an aluminum coil, insisting on replacing it instead.
Advantage copper.
I think it is fair to say the future is all aluminum coils, both because of the cost savings in the cheaper metal, and continuing improvements in alum inum joining and repair techniques.
If you want your new A/C or heat pump investment to last as long as possibl e, for a few hundred dollars extra, ask you contractor if the make and mode l they are offering is available with a 'Coastal' or 'Sea-Side' option. Uni ts with this option are made with their coils coated with a very thin, but completely corrosion resistant polymer, and are assembled using stainless s teel screws and bolts. They are intended for use near the ocean, but are eq ually good at resisting corrosion caused by a range urban threats from acid raid to cat pee.
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On Saturday, March 31, 2012 at 5:47:00 AM UTC-7, Smarty wrote:

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 de sign. 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 cl eaning are ineffective on spine-fin coils.
Copper tube coils with aluminum fins versus all-aluminum tube coils with al uminum 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. m anufacturers to anticipate future copper metal price spikes in considering potential future cost and potential copper shortages. Aluminum metal is ple ntiful, 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 al uminum. Copper is much easier to join and repair. New aluminum soldering al loys were developed over recent years that have improved the process of pro ducing 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 refrigeran ts 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-410 a) which operates at higher pressure than R-22, so the tubing used in makin g 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 ou nce for ounce, is less than that of R-22. Combined with other physical prop erties, 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 eva porators (at the furnace end) become N-coils to absorb the heat from the ai r stream, and condensers (found outdoors to move the heat into the air) mus t be much larger to handle double the flow of refrigerant. EPA also mandate d 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 galvaniz ed steel frames, which is a recipe for galvanic corrosion over time. Alumin um metal reacts with the oxygen in the air to produce a thin, but tough oxi de coating that protects the underlying metal from corrosion. If the alumin um metal is scratched or scuffed, the protective oxide layer reforms almost immediately. Aluminum coils are all aluminum, and being homogeneous, do no t suffer from galvanic corrosion the way three-metal copper coils do. But t he 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 bot h copper and aluminum coils, chloride attacks aluminum coils much more aggr essively.
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 a cid 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 o f damage to U.S. HVAC equipment - hydrogen sulfide off-gassed by impurities in imported Chinese drywall. Because of its protective oxide layer, alumin um does not react with hydrogen sulfide the way copper does.
Advantage aluminum.
5) Field serviceability - Repairing aluminum refrigeration tubing is much m ore challenging than repairing copper tubing. Copper can be heated all the way to cherry red glow without damage. It can be both brazed (temperature o ver 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 ten acious layer of aluminum oxide mentioned earlier, solder or braze filler me tal alloys have difficulty bonding to aluminum. Recently developed exotic a nd expensive fluxes are making field repair easier, but some technicians st ill 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 lon g 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-Sid e' option. Units with this option are made with their coils coated with a v ery thin, but completely corrosion resistant polymer; they are assembled using stainless steel screws and bolts, and are painted with an extra durable paint. Coasta l 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 ac id 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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