Let's fight about aluminum wire!

[Zwy]

Copper is great for boilers and plumbing.
But is sure is expensive to repair.

I have been on SOOOO many boiler jobs where the copper is eaten with holes throughout.

I've been on many jobs to replace an aluminum tube and fin evaporator with a copper tube and fin.

Copper isn't cheap and it isn't for those who don't demand a higher standard.

And copper coils in hvac was ok in the beginning when thick tubing was used, but when epa started requiring efficient standards, coils were just too thin, and they all failed.

Again, I have replaced many aluminum tube and fin evaporators with copper tube and fin. And copper is more efficient than aluminum on heat transfer, thermal conductivity and co efficient. Aluminum holds the edge on emissivity in the higher infrared range.

Don't believe me? Take to 2 plates of exact same dimensions, one aluminum and one copper. Heat both at the same rate in your hand on the end with a torch. Let me know which one you drop first.

I didn't just fall off the turnip truck. It had nothing to do with the EPA, it was due to the cost of copper.

Every mini split I've installed has copper tube and fin. Every heavy duty application that requires longevity has copper tube and fin. Long term aluminum tube and fin evaporators fail. Copper tube and fin can be missing half the aluminum fins, yet it still has good heat transfer. Same goes for condensers.

The only reason one sees aluminum condensers is due to parallel flow in order to cut weight/size and try to gain efficiency with small passages in each tube. This increases the surface contact area of the tube. Parallel flow has it's problems, but is cheap to manufacture. The small passages plug over time leading to decreased heat transfer as refrigerant is not flowing thru the passages.

Aluminum lasts. It is superior to copper in wet environments. It has points of failure, but better than copper when done right.

I call BS, reasons stated above.

It just has to have more surface area to be as efficient with heat transfer.

You are incorrect. Go check your Machinery's Handbook.
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[bolhuijo]

Every mini split I've installed has copper tube and fin. Every heavy duty application that requires longevity has copper tube and fin. Long term aluminum tube and fin evaporators fail. Copper tube and fin can be missing half the aluminum fins, yet it still has good heat transfer. Same goes for condensers.

The only reason one sees aluminum condensers is due to parallel flow in order to cut weight/size and try to gain efficiency with small passages in each tube. This increases the surface contact area of the tube. Parallel flow has it's problems, but is cheap to manufacture. The small passages plug over time leading to decreased heat transfer as refrigerant is not flowing thru the passages.

Toyota's been putting 100% Aluminum micro channel evaps and condensers in their cars for about 20 years now. They stick those things in the front of the car and let 'em collect dirt, rain, bugs, gravel at 70mph for 10 years and they still work. Not sure why they can't catch on in stationary applications.

 

[Zwy]

Toyota's been putting 100% Aluminum micro channel evaps and condensers in their cars for about 20 years now. They stick those things in the front of the car and let 'em collect dirt, rain, bugs, gravel at 70mph for 10 years and they still work. Not sure why they can't catch on in stationary applications.

That is a parallel flow condenser. It is used in automotive applications because it is cheap to manufacture and can have a higher heat exchange in a smaller package due to the micro passages.

I've installed hundreds in retrofit situations where the original copper tube and fin could not condense the refrigerant on a R134a retrofit. There is a place for a parallel flow condenser.

It doesn't change the fact that copper outperforms aluminum when it comes to heat transfer, co efficient and thermal conductivity.

Part of the reason you won't see this type of condenser adopted in stationary is a stationary system is expected to last longer than the average automotive lifespan. Second, the airflow requirements are completely different and the fan operation is much different. Third, stationary frontal area is really unlimited unlike automotive which has space constraints.. Fourth, the purposes of each system are opposite when it comes to heat pumps compared to automotive air conditioning. A heat pump is used for heating and cooling. The automotive air conditioner is used for only air conditioning. Thus the requirements are very different.

If you saw the automotive condenser failures I see in a season with parallel flow condensers, you would agree with me that stationary is best served with copper. Some of the heavy duty stuff like CAT and other heavy off road are starting to use parallel flow. I keep fast moving truck condensers in inventory as these commonly fail or are damaged by road debris and vibration. The anti icing agents used on highways just eats aluminum parallel flow condensers away between the mounts and end caps. The equipment I service lasts way longer than passenger vehicles, thus I see the longer term failures.

Sure, adopt more aluminum parallel flow condensers, it's very good for my business. Easy money........