Anode rod replacement on AO Smith Heater

**ktvaughan** · 08-29-2010, 01:43 PM

I have a AO Smith KGA-40-916 heater that is about 20 years old.
It has been reliable and I keep it flushed.
We have softened well water and there is never much sediment.
I have not touched the anode rod (I've lived here 13 years).
The anode plug has a raised "U" on the top.
Is that the magnesium or aluminun rod?
What are the consequences of not replacing it (it could be original).

**jimbo** · 08-29-2010, 03:49 PM

I can't see any point in trying to replace the anode in a 20 year old heater. Way too late, and messing with it may cause damage. How many more years do you think you should get on that ?

**ktvaughan** · 08-29-2010, 05:27 PM

Point taken.
Just interested in doing anything I can to keep it going.
Maybe I should count my blessings and plan for failure.

**Redwood** · 08-29-2010, 06:02 PM

Originally Posted by ktvaughan

Point taken.
Just interested in doing anything I can to keep it going.
Maybe I should count my blessings and plan for failure.

Yep! That's what I would recommend.

**ktvaughan** · 08-30-2010, 05:18 PM

It looks like the anode rod has been replaced by a square-head galvanized plug anyway.
Are there any consequences of having no anode rod outside of the lifespan of the tank?
It seems to be doing OK after ~20-23 years.
Water is softened well water.

**jadnashua** · 08-30-2010, 06:53 PM

Water is sometimes called the universal solvent...eventually, it can disolve anything. The basic tank is steel. It is coated with a layer of glass. It isn't perfect, and depending on how it is actually manufactuered, and transported, it is likely to have some defects. Water that can get to the steel will cause it to rust. An anode is correctly called a sacrificial anode...it is preferentially getting used up in preference to turning the steel to iron oxide (rust). So, no anode, shorter life, since it attacks the steel (iron) rather than the (missing) anode. You only get just so much 'reaction' as the water passes through, so if you can keep using up the anode, those defects don't get bigger and eventually create holes so the tank leaks and then fails.

**ktvaughan** · 08-31-2010, 05:48 AM

Why would the previous owner have removed the anode rod and replaced with a cap?
Is it because of odor in the water (water is softener well water).
Trying to determine what the best options are for the replacement..........

**Redwood** · 08-31-2010, 09:07 AM

The removal may have been odor related.
If when you install a new water heater you have an odor problem use an aluminum/zinc/tin anode rod.
I wouldn't touch a thing on this water heater with it being the difference of buying a new one today vs. next week.

**jadnashua** · 08-31-2010, 11:21 AM

Yes, I think you are on borrowed time. As noted, they do make alternate material anode rods if you have a problem with your water reacting with the stock one. A few companies make SS tanks and a few out of plastic, and those may not have an anode in them. The vast majority of those installed, do have an anode. FWIW, metal hulled boats, buoys, bridges, etc. all generally have sacrificial anodes installed, and they must be monitored and replaced periodically or the stuff will rust away. Ever wonder how a steel ship in salt water didn't rust away to nothing quickly? The paint helps, but the anodes are as big if not a bigger factor.