|What are the chances that you will get galvanic corrosion with your
copper tube, aluminum fin collector?
The Copper/Aluminum Collector uses copper riser tubes and aluminum fins. Since copper and aluminum are fairly widely separated in the galvanic series, there is the possibility of galvanic corrosion of the aluminum.
To get galvanic corrosion, you need 1) dissimilar metals, 2) electrical contact between the metals, and 3) a fluid path for the metal ions to travel along. If any of these three factors are not present, galvanic corrosion will not occur. The steps below are intended to keep the last two items from happening.
I recommend that the following steps be taken to reduce any chance of galvanic corrosion:
On the other hand, if you just take bare aluminum and form it around bare copper with nothing in the interface to separate the two or to prevent water (condensation) entry, then I'd guess its pretty likely you will get corrosion.
There is a bit of "track record" data out there on similar collectors indicating that with some precautions corrosion has not been a problem:
If a small amount of corrosion should occur, the aluminum is the sacrificial metal in this pair, so it would be the one that would be "eaten", which would not cause leaks in the collector.
So, I think that with reasonable precautions galvanic corrosion is not likely to be a problem -- but, no guarantees :)
Gary July 12, 2009