Isotherm Fridge - Outlet Anode

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fmoran

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How often does the anode need to be replaced and what are the telling signs to do. What do you need to do to replace, and how easy is it to do. Where can you buy the anode. Mine still looks like new after 2 years, but maybe I am just hopefull.
 
This anode is fitted to protect the DZR brass hull fitting from corrosion as far as I can tell from the website, but I would have liked to have found some more detail about how and where it is fitted.

Actually DZR brass should normally not need an anode to protect it. It is the next best material from which sea-cocks and skin fittings are made after bronze.

There will be no need to replace it until it is substantially corroded away. Anodes in critical locations, such as sail drive legs, are normally changed when they get to half their original size but in this case you can happily allow much more wastage than that, especially as it probably is not really necessary.

It is, however, surprising that in use with a brass fitting it has not wasted faster. Perhaps you should check the bonding, the electrical connection, between it and the hull fitting .

Unless the hull fitting is showing signs of dezincification, a general pink colouration rather than the usual colour of brass I don't think you have anything to worry about.
 
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VicS said:
This anode is fitted to protect the DZR brass hull fitting from corrosion as far as I can tell from the website, but I would have liked to have found some more detail about how and where it is fitted.

Actually DZR brass should normally not need an anode to protect it. It is the next best material from which sea-cocks and skin fittings are made after bronze.
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I believe that early versions of this heat exchanger suffered from galvanic corrosion problems. When my son had his refrigeration business he encountered severe corrosion in several units, giving them a short working life. The problem was then solved by a materials change and he reported far better reliability. However, it could be that the anode is a 'just in case' addition, accounting for the lack of wastage in the OP's case.
 
it could be that the anode is a 'just in case' addition
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Sailorman's link may not have been very useful but it does say "If you have reasons to suspect that there could be a risk of galvanic corrosion aboard, the special sacrificial anode for the SP skin fitting should be fitted"

So it appears to be optional and normally only fitted when a need is anticipated or found.

What surprises me is that "still looks like new after 2 years".
If you bond a bit of zinc (I guess its not large) to a brass through hull then you'd expect it to so some signs of wasteage in that time whether it was doing anything useful or not. Hence my suggestion to check the bonding/contact between the two.
 
Isotherm SP anode

In 10 years I have changed my anode once, the system has been in use while afloat for about 7 years of that period in waters hot and cold. The (bolt on to the fitting) method of attachment appears to ensure good bonding. After 6 further years (since change) it has deteriorated little. So, as Isotherm say, unless there is some kind of problem going on (and there can be stray currents etc etc arising for various reasons) there is probably little need for the anode. I had the opportunity to change mine so I did - I probably will not bother again.
 
Also I have managed to get further in to the Isotherm website and print off some more relevant information
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Congrats on finding that. I didnt find any more than Sailorman did and that was not very helpful :(

All your questions answered then.
I think I'd get my ohms meter on it and make sure there really is a connection between the anode and the through hull.
 
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