| Anode EvaluationIf the anode rod has more sacrificial | | | | Hex Head On Older ModelsTo find the hex head on |
| metal than exposed steel rod, then it is still in good | | | | older water heaters, simply unscrew the screws |
| shape. However, if the entire surface becomes | | | | holding the top in place, mark the placement of the top |
| covered in calcium carbonate and this calcium | | | | and the water heater with a marker, then remove the |
| carbonate becomes hard, this will prevent the anode | | | | top to find the hex head. Alas, many heaters found in |
| from protecting the tank any longer. This is known as | | | | today's buildings have foamed-in tops and can't be |
| passivation. If the anode has passivated, it will not look | | | | removed. Again, if the hex head is not exposed at the |
| so by sight alone. To test for passivation, you must | | | | time of purchase, don't purchase that particular tank. |
| bend the anode rod by hand. At the bend, observe for | | | | Look for a tank with an already exposed hex |
| small amounts of flaking. The anode should be | | | | head.Anode InspectionAnodes should be inspected at |
| replaced if more areas of the rod are exposed wire | | | | least every two years where softened water is used |
| than sacrificial metal. It should also be replaced if the | | | | but at least every four years under normal water |
| top or bottom of the rod has deteriorated, exposing six | | | | conditions. On occasion, the location of the anode is |
| or more inches of exposed wire. An anode should also | | | | actually written on the water heater instructions.Anode |
| be replaced if the anode is less than half of the rod's 3 | | | | InstallationTo remove the old rod, pull it as far out as |
| 4 in. diameter size. If the anode has passivated, split | | | | possible, bend it, then pull it the rest of the way out. To |
| through its length, or has become heavily pitted, it could | | | | install the new one, bend the rod directly in the middle, |
| also be time for replacement. When all the sacrificial | | | | insert it half way, straighten it against the opening, and |
| metal has worn away, then the steel rod will begin to | | | | install it the rest of the way. Screw in the anode rod at |
| wear away. After the steel rod wears away, the only | | | | this time. If you are unable to screw it into place |
| thing left will be the hex head or the hot water outlet | | | | because it is too bent, pull it partially out and use the |
| nipple if it is a combination anode. At this point, the tank | | | | opening to straighten it further. If there is not sufficent |
| will begin to corrode. If the anode is found in the above | | | | ceiling room to install the new anode rod, consider a |
| stated conditions, damage to the tank may have | | | | link-anode. These anodes have many small links |
| already occurred.Hidden Hex Head On Newer | | | | hooked together and look similar to links of sausages. |
| ModelsHex heads are threaded watertight plugs about | | | | You can also try zinc anodes because they bend far |
| 3/4 inches in diameter. They are attached to anode | | | | easier than magnesium ones. Another way to install an |
| rods at the top of water heaters. Some are easily | | | | anode is to drain the water heater and tip it over |
| seen from the top of the water heater. Other times it | | | | enough to allow easy access for the |
| will be under fiberglass or under a piece of plastic. To | | | | anode.LengthAnodes are typically 3 feet 8 inches. |
| locate the hex head, drill a shallow 1/4 inch hole through | | | | Anodes should be only a few inches shorter than the |
| the plastic top of the water heater. Do not drill deep | | | | tank itself. Buy anodes that are a little too long instead |
| into the tank itself. Use a long flat-head screwdriver to | | | | of a little too short. This way you can cut the anode |
| probe underneath the top of the water heater to find | | | | shorter if it is too tall.Impressed-Current RodIn relation |
| the hex head. On gas heaters, the hex head will be the | | | | to commercial water heaters, there are impressed |
| same distance from the flue as the hot and cold lines | | | | current rods. These rods do not self-generate currents |
| are. On electrics, the anode will be off center so as | | | | like sacrificial anodes. They derive power from an |
| not to drop on the heating elements. A few holes may | | | | electrical power source. Many commercial heaters |
| need to be dug in order to locate the hex head. Once | | | | give the location of the impressed-current rod. They do |
| the hex head is found, it should be permanently | | | | not need to be replaced throughout their lifetime. They |
| exposed. Use a hole saw capable of cutting plastic or | | | | may need periodic cleaning. Simply wipe them off with |
| metal to carve a hole big enough to allow future | | | | a towel. If rust appears inside a water heater with an |
| access to the hex head. Use two people at this point | | | | impressed-current rod, you should either call the |
| to unscrew the hex head--one to steady the tank, the | | | | manufacturer, call a plumber, or install sacrificial |
| other to use a breaker bar and a socket that fits the | | | | anodes.Copyright 2006 John HaynesDo you want to |
| head. Anywhere from 3/4 inch to 1-1/16 inch.In the | | | | KNOW more than the water heater salesman? Check |
| future, when buying a new water heater, purchase | | | | out which provides insight into warranties, insulation, and |
| only those with already exposed hex heads.Hidden | | | | accessibility. |