How long will your water heater last? Your anode rods will tell us
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 tank lining. As long as the anode is present and working, almost all corrosion or rust on the tank lining is prevented.
Access
For all consumers shopping for a new water heater, an important aspect of the new appliance is accessibility to its anode rod. On top of the water heater is a part called the hex head. It is visible or not. If not visible, the hex head is located under the sheet metal top or plugs under the hot water outlet. You shouldn’t have to settle for a hard to find anode rod. I recommend not buying this water heater. Look for a water heater with an easy-to-find hex head.
For commercial water heaters, the outer sheet metal top of the water heater must always be removed to access the anode rod. The hex head is rarely found exposed, whether it is an electric or gas heater. As you remove the top of the heater, mark the top of the heater for easier assembly later. At this point, the hex head for the anode rod can be easily found on any commercial electric heater. On gas heaters, the hex head will probably be easy to find if you have only one flue. If you have more than one vent, it may be more difficult to locate.
Aluminum
An anode is made of aluminum, zinc, or magnesium. It forms around a wire that runs through the center of the rod. Hard water areas of the country often have aluminum rod water heaters installed because aluminum is the best material for hard water conditions. If the anode rod has worn down to the wire or gone completely, this is usually a sign of hard water. However, be careful with aluminum anode rods. Science believes there is a link between dietary aluminum and Alzheimer’s disease. Do not drink or cook with hot water from a tank that uses an anode rod made of aluminum. To determine if you have an aluminum anode rod, remove it and then bend it. If it bends easily in your hands, it’s probably made of aluminum.
combined anode
Anodes are typically installed with 3/4 in. hex heads screwed into the top of the tank. However, a matched anode is attached to the nozzle of the hot water outlet pipe, also screwed on top. All water heaters have at least one anode rod. Some water heaters have longer warranties because they have two anode rods. If there are two anode rods, that’s because one is attached to a hex head at the top and the other is a combination anode attached to the hot water outlet. However, some residential heaters have two hex head anode rods and do not have combination anodes.
To find out if you have a combination anode rod, disconnect the hot water outlet at the top of the heater with a pipe wrench. Don’t forget to turn off the water first! Next, insert a stiff wire through the hole where the hot water nipple was. If it stops 3 to 6 inches straight down, then you have located the combined anode. If the wire finds nothing inside, the anode is somewhere else. The combined anode can be removed with a pipe wrench.
If you do not have a combination anode and wish to install one, remove the nipple from the hot water line and replace it with a combination anode rod. The anode nozzle should be longer than the thickness of the insulation on top of the heater, which is typically 2-6 inches.
Magnesium
Magnesium is used more often than the other metals for anodes. When the water in your area isn’t particularly hard, it’s probably best to use magnesium bars. However, be careful with magnesium rods when replacing them in an already corroded tank. The electrochemical reaction of the new magnesium anode can cause hydrogen gas to build up in the tank. This can cause water leaks.
Zinc
Newer 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. The sole purpose of the zinc in an anode rod is to reduce the sulfur odor in the water.
Anode consumption
Softening hard water with salt is actually more damaging to anodes than 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 effect 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 in predictable ways. Most of the time it corrodes at the top or bottom and exposes the steel wire underneath.
center wire
The water heater will only be protected if the anode rod has enough metal hanging out. The steel core wire holds the sacrificial metal at the anode. Be sure to inspect the anode for an exposed core wire at least every two years.
When an anode rod is tested for exposed core wire, the wire may become coated with calcium carbonate which is easily removed. This calcium carbonate is not corroded metal from the anode rod, so don’t worry about removing it.
Anode Rating
If the anode bar has more sacrificial metal than the exposed steel bar, it’s still in good shape. However, if the entire surface becomes covered with calcium carbonate and this calcium carbonate becomes hard, this will prevent the anode from protecting the tank any longer. This is known as passivation. If the anode has been passivated, it will not appear so to the naked eye. To test passivation, you need to bend the anode rod by hand. On the curve, look for small amounts of flaking. The anode should be replaced if more areas of the rod are exposed to the wire than to the sacrificial metal. It should also be replaced if the top or bottom of the rod has deteriorated, exposing six or more inches of exposed wire. An anode should also be replaced if the anode is less than half of the 3/4 in. diameter size. If the anode has become passivated, split along its length, or badly pitted, it might also be time to replace it. When all of the sacrificial metal has been worn away, the steel bar will begin to wear away. After the steel rod wears away, the only thing left will be the hex head or the hot water outlet nozzle if it is a combination anode. At this point, the tank will begin to corrode. If the anode is in the conditions listed above, damage to the tank may already have occurred.
Hidden hex head on newer models
Hex heads are threaded watertight plugs approximately 3/4 inch in diameter. They are attached to anode rods at the top of the water heaters. Some are easily seen from the top of the water heater. Other times it will be under fiberglass or under a piece of plastic. To locate the hex head, drill a shallow 1/4-inch hole through the plastic top of the water heater. Do not drill deep into the tank itself. Use a long flat head screwdriver to probe under the top of the water heater to find the hex head. On gas heaters, the hex head will be the same distance from the flue as the hot and cold water lines. In electricity, the anode will be off center so as not to fall on the heating elements. It may be necessary to dig some holes to locate the hex head. Once the hex head is found, it must be permanently exposed. Use a hole saw capable of cutting plastic or metal to carve a hole large enough to allow future access to the hex head. Use two people at this point to unscrew the hex head: one to stabilize the tank, the other to use a breaker bar and socket to fit the head. From 3/4 inch to 1-1/16 inch.
In the future, when buying a new water heater, buy only those with exposed hex heads.
Hidden hex head on older models
To find the hex head on older water heaters, simply unscrew the screws that hold the top in place, mark the location of the top and water heater with a marker, then remove the top to find the hole. hex head. Unfortunately, many heaters found in buildings today have foam covered tops that cannot be removed. Again, if the hex head isn’t exposed at the time of purchase, don’t buy that particular tank. Look for a tank with a hex head already exposed.
Anode inspection
Anodes should be inspected at least every two years when softened water is used, but at least every four years under normal water conditions. Sometimes the location of the anode is written in the instructions for the water heater.
Anode installation
To remove the old rod, pull it out as far as it will go, bend it, then pull the rest out. To install the new one, bend the rod straight down the middle, insert it halfway, straighten it against the opening, and install it the rest of the way. Screw in the anode rod at this time. If you can’t screw it in place because it’s too bent, pull it out part way and use the opening to straighten it out more. If there isn’t enough room on the roof to install the new anode rod, consider an anode link. These anodes have many small links hooked together and resemble links on sausages. You can also try zinc anodes because they bend much easier than magnesium ones. Another way to install an anode is to drain the water heater and tilt it just enough to allow easy access to the anode.
Length
Anodes are typically 3 feet 8 inches. The anodes should be only a few inches shorter than the tank itself. Buy anodes that are a bit too long instead of too short. This way you can cut the anode shorter if it is too tall.
Printed Current Rod
In relation to commercial water heaters, there are impressed current rods. These rods do not self-generate currents like sacrificial anodes. They get power from an electrical power source. Many commercial heaters give the location of the printed current bar. They do not need to be replaced throughout their useful life. They may need periodic cleaning. Just wipe them off with a towel. If rust appears inside a water heater with an impressed current rod, you should call the manufacturer, call a plumber, or install sacrificial anodes.