Quote:
Originally Posted by Casita Greg
My HWH is a porcelain lined steel tank, as are the majority of them. I can't recall seeing any with aluminum tanks, but I'll take your word for it that they exist.
I guess my question would be is whether the whole aluminum HWH tank becomes an anode then? After all, the two main "noble metals" primarily used for sacrificial anodes are Magnesium and Aluminum. Just wondering?
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Atwood's PDF says...
"The Atwood water heater is constructed of a core of high strength aluminum. the interior of the tank consists of a 15% thickness of 7072 aluminum (pure aluminum and zinc) which is fused to the core during the rolling process."
I assume you are technically correct in saying that the whole tank interior acts an anode.
Atwood prohibits the use of aftermarket anodes.
Suburban uses a sprayed ceramic liner as you described. Without an anode the corrosion seeks pinholes in the ceramic just like most home hot water heaters. The anode is an important component.
I don't have any data to back this up, but my guess from experience is that internal electric heating elements contribute more to internal corrosion than an external flame. So I think that aftermarket "hotrods" which go in the drain hole and replace the anode may not be such a good idea for a Suburban water heater and it might be best to get the electric heat as a factory option.
At any rate, both types generally last for decades unless they are allowed to freeze when full of water. I have seen this more than once!