What are the common reasons for and procedures for, replacing the anode tube in a common gas residential hot water heater? Does this cure the problem of lessoning amounts of hot water or is the solution to flush as described in other answers?

Hi Wlhcon1:

The anode rod has nothing to do with the volume of hot water available to the house.

The reason an anode rod is used with hot water heaters is to act as a point of SACRIFICE for the water heater. Here, instead of the anions and cations (charged particles) in the water supply attacking the tappings of the water heater they will interact with the anode rod and precipitate out of solution (usually as a salt) and deposit onto the floor of the heater. It is this precipitate that ends up being an issue and it is for that reason that you flush the water heater periodically... to remove sediments and the precipitate(s) that have formed.

Eventually the anode rod will get used up and the charged particles will start to attack the tappings of the water heater. This will quickly lead to a leaking water heater and the need to replace it.

If you have a particularly HARD WATER then you may want to change out your anode rod every 4-5 years. You would need a 1-1/16" or 1-1/8" socket and a 1/2" drive ratchet and a friend to help you remove the old rod. It would definitely increase the life of your heater... ;)

Let us know if you would like to discuss this further... glad to help.

MARK

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Mark gave you a very good explanation let me flesh it out with a visual,(see image).
He also nave you a reason to flush out your heater. Allow me to enlarge on that.

For long life and fewer troubles you should keep your heater clear of mineral build-up by FLUSHING NOT DRAINING on a regular schedule. Attach a hose to the boiler drain at the bottom of the tank. With the pressure on, open the boiler drain and let it run until the water runs clear. You will see a spurt of red,(rust) followed by white or yellow grains,(lime or calcium carbonate). This shouldn't take more then a few minutes. Do this monthly to keep it clear. Now flush out your hot water lines on ALL fixtures that are affected . Now pull each aerator and clean the screens. Be sure you put them back together the same way you took them out. Don't forget to flush it out every month. Your heater will thank you for it. Hope this helps and thank you for rating my answer, Tom