Description An anode rod is a rod made of "sacrificial" metal. Like batteries, the anode produces an electrochemical reaction in the tank. The anode slowly wears away instead of the lining of the tank. As long as the anode is present and functional, almost all corrosion or rusting on the tank's lining is prevented.
Access To all consumers who are shopping for a new water heater, an important aspect of the new appliance is the accessibility to its anode rod. On top of the water heater is a part called a hex head. It is either visible or not. If it is not visible, the hex head is either located underneath the sheet metal top or is connected underneath the hot water outlet. You shouldn't have to settle for a hard to find anode rod. I recommend not purchasing this water heater. Look for a water heater with an easily found hex head. In the case of commercial water heaters, the outer sheet metal top of the water heater must always be removed for access to the anode rod. The hex head is rarely found exposed, whether it is an electric or gas heaters. As you remove the top to the heater, mark the top of the heater itself so that assembling it together later will be easier. At this point the hex head for the anode rod can be found easily on any commercial electric heater. On gas heaters, the hex head will probably be easy to find if it has a single flue vent. If it has more than one flue vent, it may will be more difficult to locate.
Aluminum An anode is made out of aluminum, zinc, or magnesium. It is formed around a wire running down the center of the rod. Hard water areas of the country often have water heaters with aluminum rods installed because aluminum is the best material for hard water conditions. If your anode rod has deteriorated down to the wire or is gone completely, this is usually a sign of hard water. Be careful of aluminum anode rods, however. Science believes that there is a link between aluminum in the diet and Alzheimer's disease. Do not drink or cook with hot water from a tank which uses an anode rod made out of aluminum. To determine if you have an aluminum anode rod, remove it, then bend it. If it bends easily in your hands, it is probably made out of aluminum.
Combination Anode Usually anodes are installed with 3/4 in. hex heads screwed in the top of the tank. However, a combination anode is attached to the hot water outlet pipe nipple, also screwed in at the top. All water heaters have a minimum of one anode rod. Some water heaters have longer warranties because they have two anode rods. If there are two anode rods, that is because one is attached to a hex head at the top and the other is a combination anode attached to the hot water outlet. Some residential heaters have two hex headed anode rods and no combination anodes though. To find out if you have a combination anode rod, disconnect the hot water outlet at the top of the heater using a pipe wrench. Don't forget to shut off the water first! Next poke a stiff wire down the hole where the hot water nipple was. If it stops about 3 to 6 inches directly down, then you have located the combination anode. If the wire meets nothing inside, the anode is somewhere else. The combination anode can be removed with a pipe wrench. If you do not have a combination anode and you want to install one, then remove the hot water pipe nipple and replace it with a combination anode rod. The nipple on the anode rode will need to be longer than the thickness of the insulation on top of the heater, which is usually 2 to 6 inches.
Magnesium Magnesium is used more often than the other metals for anodes. When the water in your area is not particularly hard, use of magnesium rods is probably best. Be careful with magnesium rods, however, when replacing them in an already corroded tank. The electrochemical reaction from the new magnesium anode can cause hydrogen gas to build up in the tank. This can lead to water leaks.
Zinc New water heaters rarely have a zinc rod already installed. Zinc rods are actually aluminum rods with a 1/10 portion of the rod being actual zinc. Zinc's only purpose in an anode rod is to reduce the smell of sulfur in the water.
Consumption of Anodes Softening hard water with salt is actually more damaging to anodes than the calcium carbonate--the cause of hard water. Salt can consume an anode up to three times faster than usual. Phosphates can have the same adverse affect on an anode. The anode should be inspected every two years or sooner if you use these water softening agents. The anode is the reason the heater stays functional for years or even decades. Anodes corrode predictably. Most times it corrodes at the top or bottom and exposes the steel wire underneath.
Core Wire The water heater will only be protected if the anode rod has enough metal hanging on it. The steel core wire keeps the sacrificial metal on the anode. Be sure to inspect the anode for an exposed core wire every two years at least. When analyzing an anode rod for exposed core wire, the wire can be covered in calcium carbonate that brushes off easily. This calcium carbonate is not corroded metal from the anode rod, so do not worry about removing it.
Disclaimer: All information on this site is provided for informational purposes only! By no means is any
information presented herein intended to substitute for the advice provided to you by any health care or other professional
or organization.
