I just replaced a water heater that I put in in 1984! Finally gave up the ghost. The two keys to a long life are:
1. Clean out the curd at the bottom of the tank. Hook up a hose to the bottom and run some water out. If you do it in a driveway area, you should be able to see the "sand" like sediment around the discharge. This is partially the inside tank flaking off.
2. Every 3 to 5 years replace the anode rod. At the top of the tank you will see what looks like the nut end to a bolt. That connects to a dielectric rod that runs down into the tank. It is a sacrificial rod, intended to be eaten away you the corrosive items in our water supply. Better for a cheap rod to be eaten away, rather than the sides of the water heater tank.
Replacing the rod is fairly straight forward.
Turn off the water.
Drain some of the water out to relieve pressure (open a hot water spigot in the house)
Someone hang onto the water heater, because getting the old rod out will take some oomph!
Put a socket wrench on the nut at the top of the tank, grunt terribly and get it loose. You will need a 1 1/16" socket and a 1/2" socket wrench. I also slipped a piece of pipe over the end of the wrench to give be a longer lever (I love Archimedes, he helps me all the time).
This pictures show you what to expect when you remove the rod. Notice the one on the right is just a wire, i.e. the rod is totally gone.
You can get a new rod (and the wrench if you need it ) at Amazon.com http://www.amazon.com/Reliance-9001829005-32-Inch-Magnesium-Heater/dp/B003110YN8/ref=sr_1_1?ie=UTF8&qid=1376150407&sr=8-1&keywords=anode+rod
Just search for anode rod. The one at Amazon is probably shorter than what it is replacing, but that makes installing much easier. Sometimes there is not much room above the tank to put a longer rod up over the heater and down through the hole.
Tighten up the new rod into the tank (Do not use teflon tape). Snug it down, it is tapered so leaking is unlikely. Turn the water back on. Write a note on the water heater recording when you changed the rod.
Voila you have added years to the life of your tank by spending 1/2 hour cleaning it up.
This year my temperature control also went out on my gas water heater. $120 for a new one and again, 1/2 hour of work. Better than $500 for a new heater. The temp control looked a bit like the well eaten anode rod. There is a "finger" that sticks into the tank to read the temperature. It was pretty well eaten away. I got tired of 90° water when it was set on high.
Hope this is useful.
