| DescriptionAn anode rod is a rod made of "sacrificial" | | | | anode rod for exposed core wire, the wire can be |
| metal. Like batteries, the anode produces an | | | | covered in calcium carbonate that brushes off easily. |
| electrochemical reaction in the tank. The anode slowly | | | | This calcium carbonate is not corroded metal from the |
| wears away instead of the lining of the tank. As long | | | | anode rod, so do not worry about removing it.Anode |
| as the anode is present and functional, almost all | | | | EvaluationIf the anode rod has more sacrificial metal |
| corrosion or rusting on the tank's lining is | | | | than exposed steel rod, then it is still in good shape. |
| prevented.AccessTo all consumers who are shopping | | | | However, if the entire surface becomes covered in |
| for a new water heater, an important aspect of the | | | | calcium carbonate and this calcium carbonate |
| new appliance is the accessibility to its anode rod. On | | | | becomes hard, this will prevent the anode from |
| top of the water heater is a part called a hex head. It | | | | protecting the tank any longer. This is known as |
| is either visible or not. If it is not visible, the hex head is | | | | passivation. If the anode has passivated, it will not look |
| either located underneath the sheet metal top or is | | | | so by sight alone. To test for passivation, you must |
| connected underneath the hot water outlet. You | | | | bend the anode rod by hand. At the bend, observe for |
| shouldn't have to settle for a hard to find anode rod. I | | | | small amounts of flaking. The anode should be |
| recommend not purchasing this water heater. Look for | | | | replaced if more areas of the rod are exposed wire |
| a water heater with an easily found hex head.In the | | | | than sacrificial metal. It should also be replaced if the |
| case of commercial water heaters, the outer sheet | | | | top or bottom of the rod has deteriorated, exposing six |
| metal top of the water heater must always be | | | | or more inches of exposed wire. An anode should also |
| removed for access to the anode rod. The hex head | | | | be replaced if the anode is less than half of the rod's 3 |
| is rarely found exposed, whether it is an electric or gas | | | | 4 in. diameter size. If the anode has passivated, split |
| heaters. As you remove the top to the heater, mark | | | | through its length, or has become heavily pitted, it could |
| the top of the heater itself so that assembling it | | | | also be time for replacement. When all the sacrificial |
| together later will be easier. At this point the hex head | | | | metal has worn away, then the steel rod will begin to |
| for the anode rod can be found easily on any | | | | wear away. After the steel rod wears away, the only |
| commercial electric heater. On gas heaters, the hex | | | | thing left will be the hex head or the hot water outlet |
| head will probably be easy to find if it has a single flue | | | | nipple if it is a combination anode. At this point, the tank |
| vent. If it has more than one flue vent, it may will be | | | | will begin to corrode. If the anode is found in the above |
| more difficult to locate.AluminumAn anode is made out | | | | stated conditions, damage to the tank may have |
| of aluminum, zinc, or magnesium. It is formed around a | | | | already occurred.Hidden Hex Head On Newer |
| wire running down the center of the rod. Hard water | | | | ModelsHex heads are threaded watertight plugs about |
| areas of the country often have water heaters with | | | | 3/4 inches in diameter. They are attached to anode |
| aluminum rods installed because aluminum is the best | | | | rods at the top of water heaters. Some are easily |
| material for hard water conditions. If your anode rod | | | | seen from the top of the water heater. Other times it |
| has deteriorated down to the wire or is gone | | | | will be under fiberglass or under a piece of plastic. To |
| completely, this is usually a sign of hard water. Be | | | | locate the hex head, drill a shallow 1/4 inch hole through |
| careful of aluminum anode rods, however. Science | | | | the plastic top of the water heater. Do not drill deep |
| believes that there is a link between aluminum in the | | | | into the tank itself. Use a long flat-head screwdriver to |
| diet and Alzheimer's disease. Do not drink or cook with | | | | probe underneath the top of the water heater to find |
| hot water from a tank which uses an anode rod made | | | | the hex head. On gas heaters, the hex head will be the |
| out of aluminum. To determine if you have an | | | | same distance from the flue as the hot and cold lines |
| aluminum anode rod, remove it, then bend it. If it bends | | | | are. On electrics, the anode will be off center so as |
| easily in your hands, it is probably made out of | | | | not to drop on the heating elements. A few holes may |
| aluminum.Combination AnodeUsually anodes are | | | | need to be dug in order to locate the hex head. Once |
| installed with 3/4 in. hex heads screwed in the top of | | | | the hex head is found, it should be permanently |
| the tank. However, a combination anode is attached to | | | | exposed. Use a hole saw capable of cutting plastic or |
| the hot water outlet pipe nipple, also screwed in at the | | | | metal to carve a hole big enough to allow future |
| top. All water heaters have a minimum of one anode | | | | access to the hex head. Use two people at this point |
| rod. Some water heaters have longer warranties | | | | to unscrew the hex head--one to steady the tank, the |
| because they have two anode rods. If there are two | | | | other to use a breaker bar and a socket that fits the |
| anode rods, that is because one is attached to a hex | | | | head. Anywhere from 3/4 inch to 1-1/16 inch.In the |
| head at the top and the other is a combination anode | | | | future, when buying a new water heater, purchase |
| attached to the hot water outlet. Some residential | | | | only those with already exposed hex heads.Hidden |
| heaters have two hex headed anode rods and no | | | | Hex Head On Older ModelsTo find the hex head on |
| combination anodes though. | | | | older water heaters, simply unscrew the screws |
| To find out if you have a combination anode rod, | | | | holding the top in place, mark the placement of the top |
| disconnect the hot water outlet at the top of the | | | | and the water heater with a marker, then remove the |
| heater using a pipe wrench. Don't forget to shut off | | | | top to find the hex head. Alas, many heaters found in |
| the water first! Next poke a stiff wire down the hole | | | | today's buildings have foamed-in tops and can't be |
| where the hot water nipple was. If it stops about 3 to | | | | removed. Again, if the hex head is not exposed at the |
| 6 inches directly down, then you have located the | | | | time of purchase, don't purchase that particular tank. |
| combination anode. If the wire meets nothing inside, the | | | | Look for a tank with an already exposed hex |
| anode is somewhere else. The combination anode can | | | | head.Anode InspectionAnodes should be inspected at |
| be removed with a pipe wrench.If you do not have a | | | | least every two years where softened water is used |
| combination anode and you want to install one, then | | | | but at least every four years under normal water |
| remove the hot water pipe nipple and replace it with a | | | | conditions. On occasion, the location of the anode is |
| combination anode rod. The nipple on the anode rode | | | | actually written on the water heater instructions.Anode |
| will need to be longer than the thickness of the | | | | InstallationTo remove the old rod, pull it as far out as |
| insulation on top of the heater, which is usually 2 to 6 | | | | possible, bend it, then pull it the rest of the way out. To |
| inches.MagnesiumMagnesium is used more often than | | | | install the new one, bend the rod directly in the middle, |
| the other metals for anodes. When the water in your | | | | insert it half way, straighten it against the opening, and |
| area is not particularly hard, use of magnesium rods is | | | | install it the rest of the way. Screw in the anode rod at |
| probably best. Be careful with magnesium rods, | | | | this time. If you are unable to screw it into place |
| however, when replacing them in an already corroded | | | | because it is too bent, pull it partially out and use the |
| tank. The electrochemical reaction from the new | | | | opening to straighten it further. If there is not sufficent |
| magnesium anode can cause hydrogen gas to build up | | | | ceiling room to install the new anode rod, consider a |
| in the tank. This can lead to water leaks.ZincNew | | | | link-anode. These anodes have many small links |
| water heaters rarely have a zinc rod already installed. | | | | hooked together and look similar to links of sausages. |
| Zinc rods are actually aluminum rods with a 1/10 portion | | | | You can also try zinc anodes because they bend far |
| of the rod being actual zinc. Zinc's only purpose in an | | | | easier than magnesium ones. Another way to install an |
| anode rod is to reduce the smell of sulfur in the | | | | anode is to drain the water heater and tip it over |
| water.Consumption of AnodesSoftening hard water | | | | enough to allow easy access for the |
| with salt is actually more damaging to anodes than the | | | | anode.LengthAnodes are typically 3 feet 8 inches. |
| calcium carbonate--the cause of hard water. Salt can | | | | Anodes should be only a few inches shorter than the |
| consume an anode up to three times faster than usual. | | | | tank itself. Buy anodes that are a little too long instead |
| Phosphates can have the same adverse affect on an | | | | of a little too short. This way you can cut the anode |
| anode. The anode should be inspected every two | | | | shorter if it is too tall.Impressed-Current RodIn relation |
| years or sooner if you use these water softening | | | | to commercial water heaters, there are impressed |
| agents.The anode is the reason the heater stays | | | | current rods. These rods do not self-generate currents |
| functional for years or even decades. Anodes corrode | | | | like sacrificial anodes. They derive power from an |
| predictably. Most times it corrodes at the top or | | | | electrical power source. Many commercial heaters |
| bottom and exposes the steel wire underneath. | | | | give the location of the impressed-current rod. They do |
| Core WireThe water heater will only be protected if | | | | not need to be replaced throughout their lifetime. They |
| the anode rod has enough metal hanging on it. The | | | | may need periodic cleaning. Simply wipe them off with |
| steel core wire keeps the sacrificial metal on the | | | | a towel. If rust appears inside a water heater with an |
| anode. Be sure to inspect the anode for an exposed | | | | impressed-current rod, you should either call the |
| core wire every two years at least.When analyzing an | | | | manufacturer, call a plumber, or install sacrificial anodes. |