Onan electrolysis

John and Anne on Bali Hai <hollamby@...>

Hi Ian,

I had a problem after 30 months. I had overlooked replacing the anode
in the heat exchanger and it had disintegrated.My unit was grounded
when I got delivery in January 2001. The electrolysis had not damaged
the unit itself so far as I could see BUT the bronze end plates had
become dezincified and the outboard one had cracked right across. Only
the neoprene gasket had saved me from a potentially disastrous
leak.Also the paint was peeling off the unit. I repainted it and
fitted new endplates from Onan.

Strangely enough I have recently replaced the anode after a further 18
months and found it to be in good shape being only about 30-40 percent
wasted and the paint was also perfect. The easiest way to check the
condition of the unit is to take it off completely, also the remains
of the old zinc can be unscrewed from the holder and replaced with a
new zinc at much less cost.

I have no idea why the elecrolysis appears to have stopped. It might
have something to do with the fact that I replaced the magnesium anode
in the hot water heater a year ago and this resulted in the hot water
being 'fizzy' for a couple of months during which time I assume the
new anode disolved. Earlier on the mild steel 5 litre pressure vessel
behind the gen set failed becausse of electrolysis and when I replaced
it I used plastic fittings to connect it and that seems to have solved
that problem (at least the tap water has not started looking rusty red

Best wishes from Malta, Anne and John Hollamby, Bali Hai No 319

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