Fresh Water Exchanger Pencil Zinc Issues

[ArtJ]

A while back I posted about Pencil Zincs for the MMI Exchanger issues.

The zinc would not come out and plated itself to the threads

I bought different Zincs from MMI, hoping they would be different.
This spring when I went to replace the zinc I found that it separated
from the cap and had replated itself to the threads.
I had West Marine sort thru their zincs from Marytr (sp?)
Later found that those zincs were also made of Aluminum.

WHAT DO we NOW do to protect our heat exchangers and how
will we clean out the residue of these aluminum zincs?

Best Regards ArtJ

[edwardc]

Remove the HX and pull the end plates. The spent zinc debris will be easy to clean out. Also, get a wire coat hanger and rod out the tubes.

Use a tap to clean out the threads and test fit with a new zinc before reassembly.

Reassemble the HX with new rubber disc and washer seals (available in the MMI store) and a new zinc.

Change the zinc more often, so it will come out in one piece. Twice a season is not unreasonable.

[ndutton]

Several questions for you Art:

1. Are your anodes zinc or aluminum? From the post I'm not sure.
2. Is your boat in salt or fresh water?
3. How long between zinc changes?
4. How long does does your shaft zinc last?
5. Is it zinc or aluminum (or magnesium)?
6. Is your boat in a marina?
7. Do you have shore power?
8. If yes, do you have a DC negative to AC ground bond wire?
9. If yes again, do you have a galvanic isolator?

[Golfdad75]

No zinc?

I have a Sen Dure heat exchanger. Is is it possible that I have no zinc?

[ndutton]

There should be one or two small threaded plugs near the bottom (mine has two). That's where the zinc goes.

[Golfdad75]

Zinc size

How long a zinc? I know it is 1/4

[ndutton]

My HX uses a 1/4" x 2" zinc but yours may not be the same. Put a pencil in the open port and measure the available depth.