Marine Air Corrosion

[Marc14857]

Was doing some maintenance on my AC systems today and noticed that the system has started to corrode pretty significantly. See Pics. I have never had problems with galvanic corrosion as anodes show moderate corrosion at the end of the season and I have isolators on the AC side. Obviously operating in a salt water environment. Do marine air systems have anodes that I should be replacing? Can't find anything in owners manual.

 

[Marc14857]

I wonder if this green grounding wire on the control circuit cable bundle which was dangling in the air has anything to do with the problem? My other AC unit shows no sign of corrosion and the green cable is grounded to the frame

 

[thinwater]

Was doing some maintenance on my AC systems today and noticed that the system has started to corrode pretty significantly. See Pics. I have never had problems with galvanic corrosion as anodes show moderate corrosion at the end of the season and I have isolators on the AC side. Obviously operating in a salt water environment. Do marine air systems have anodes that I should be replacing? Can't find anything in owners manual.

Aluminum fins and copper tubes. Very hard to protect against salt.
a. there is nothing anodic to aluminum, unless there is a magnesium alloy available. But it won't help much.
b. A regular rinse with fresh water would probably help as much as anything. It is the chloride that's killing you.

I'm guessing corrosion was slow until the copper became exposed, and then it took off like a race horse.

 

[Stu Jackson]

Aluminum fins on CU tubes is a "basic" least cost standard in the industry, although there are other materials that are offered by manufacturers of HVAC equipment, don't know if so for marine units.

General maintenance instructions call for regular cleaning of the fins for industry equipment.

Something started that, don't know what. Your choices are to keep it clean and live with it, or replace the whole coil. If you keep it, it will only get worse and reduce your cooling.

Sorry to hear about your issue.

 

[kloudie1]

Steel pan with copper tubes and time.. all ya need.. Most of the water that this stuff sees is distilled water from the condensation from the air.. Salt does not get in there much at all.. Yes the green wire should be connected but probably won't make much difference in corrosion. As the paint on the pan degrades, more and more steel is exposed to become active against the aluminum.. Best to try to get the water level down in the pan . Move the drain or use shims to tilt the pan (while still supporting it) so the water goes out of the pan and does not immerse the lower parts of the fins..

 

[petersea]

Marc, reconnect the green wire but use a nut and bolt and lose that self tapping screw. One of my units had a loose ground caused by the sefl tapping screw becoming loose (vibrations ?) Any way not sure you can do anything about the unit now but my suggestion is to clean it, coat the exposed steel to stop more rust, reground it and keep using it until the inevatable. Amazing what we find to do to keep busy when it is raining out ! ! Enjoy the rest of your vacation now that the rain has stopped !