Sacrificial anodes on water heaters?

[ChasB]

I've just found out that my water heater came with a sacrificial anode which should have been checked annually.

So a heads up to folks here to read their manuals.

And a question - if I have a galvanic isolator fitted, do I need to worry about the anode on the water heater? Seems to me I don't.

 

[tillergirl]

Good question. I have read the manual and even have a spare anode - there's posh. But do I need to bother to change it annually? I think the isolator question is easier. Surely the isolator protects 'the boat' whereas this anode is merely protecting the calorifier. But having seen the size of the anode for the calorifier, annually? Seems a lot of zinc to have gone into the fresh water but then I suppose if you have a stray current it will zap away very quickly. I suppose I ought to withdraw the old one and have a look.

 

[oldsaltoz]

You have answered your own question successfully.

<<<I suppose I ought to withdraw the old one and have a look>>>

By the way, you have the same arrangement in your hot water system in most homes, that big nut on top holds the anode, and it runs from the top and is just short of the bottom regardless of total height. The small rapid recovery systems last about 3 to 5 years and the larger ones up to 8 years, after that it starts eating the steel tank if the glass coating has failed inside.

Avagoodweekend......

 

[tillergirl]

But that's not what II wanted to hear!

 

[VicS]

[ QUOTE ]
if I have a galvanic isolator fitted, do I need to worry about the anode on the water heater

[/ QUOTE ] As already indicated they are separate issues.

If you have shore power connected (connected, not necessarily in use) A GI is a sensible item to fit, maybe essential but you wont know that until its too late. It will protect all your underwater fittings (at least those such as stern gear and anodes that are connected also to the shorepower earth) from corrosion by stray currents that can arise from dodgy installations on other boats also connected to the shorepower system.

A GI is located in the incoming shorepower earth wire. It allows small currents from mains voltage sources to pass thus ensuring continued protection that earths give and reliable operation of your RCD but blocks currents from low voltage sources that cause the galvanic or electrolytic corrosion of the underwater bits.

The water heater anode will specifically protect your water heater. It should be checked and replaced as advised by the manufacturers. It will be just as important even if you do not normally leave your shore power connected.

 

[Piers]

I have a Torrid water heater with an anode fitted. Unfortunately, the way the heater is installed makes it impossible to check the anode, and I mean impossible. Fleming has said they have never had a problem with them, and have given a life-time warranty on it for me!