One thing to be aware of is that Suburban sells two different anode rods. One is made of magnesium and one is made of aluminum. The version that came installed in your water heater is the mag one. It deteriorates faster then the alum one and Suburban states to use the mag one as long as it lasts at least a year. I think it provides better protection because it breaks down faster. They look about the same and when shopping for a replacement, you have to read the packaging closely to see which one you've got.
I've also seen the ones at CW that have the built-in drain valve. As I recall, the anode itself is made of aluminum and is also fairly short.
I personally will only use the mag ones. I WANT them to deteriorate at a good rate. I'm just a little uncomfortable about using the aluminum version.
FWIW, all the non-Suburban anode rods I've seen at CW seem to be made of aluminum.
My .02
Tim
