How to Change a Water Heater Anode Rod - DIY Tips

If you're wondering how to extend the life of your water heater and prevent costly repairs, replacing the anode rod is a critical step.

The anode rod protects your water heater from rust and corrosion by attracting corrosive particles to itself, sacrificing its own material. Over time, the anode rod will deteriorate, and without regular replacement, the water heater tank can suffer permanent damage.

But don't worry, in this guide, we'll walk you through the steps on how to change a water heater anode rod, so you can ensure the longevity and optimal performance of your water heater. Let's get started!

How to change a water heater anode rod: Things to consider

• What are anode rods? Are anodes necessary?
• How does the water heater anode work
• Common anode problems and repair tips
  
• The most used types of anode rods; zinc, magnesium, aluminum, and powered
• How to replace an anode rod in hot water heaters
• What to do if an anode is stuck

What are anode rods? Are anodes necessary and do they have to be replaced? How often?

Water heater anode rods, also known as sacrificial anodes, are essential components in water heating with one primary role: to protect the metal tank from corrosion.

Most hot water heaters come equipped with one or more anode rods made of different materials. Anode service depends on water conductivity, as the rod deteriorates over time. This is why it is necessary to maintain the anode rod to keep the tank in operating condition. A depleted anode rod does not affect the water taste or color, and regular inspection and replacement can extend the heater's life.

Under normal conditions, the water heater anode rod will be consumed and completely gone in 5-10 years (depending on water chemistry and element quality), and the metal tank will start to corrode.

Heaters have different warranties based on the number and quality of anodes. For example, medium-quality appliances come with the most common warranty of six years. Models equipped with two rods or have one large or heavy-duty anode rod are better, as they allow manufacturers to provide a longer warranty (up to 12 years).

How does the water heater anode rod work? What are anodes made of?

Tank-type water heaters, including RV type such as Atwood or Suburban, can be equipped with aluminum, magnesium, or zinc water heater anode rods, but not tankless  types as they do not have a storage tank.

Depending on the water hardness, chemical structure, and hot water usage, anode rods react differently and protect the heater more or less. The inside of the anode is made of a steel wire core, with better quality rods using stainless steel.

The tank is typically constructed of steel and must be protected against the aggressive and acidic nature of water. There are two ways to defend the tank from corrosion: installing anode rods and built-in tank lining.

The inner tank surface is factory-coated with glass or porcelain lining, but complete coverage is sometimes neglected due to manufacturing imperfections or damages (such as cracks) from handling and transportation.

Potable water contains oxygen, calcium, and magnesium, making it conductive or electrolytic and allowing electricity to flow through the water - from one metal (anode) to another (cathode). By changing the water structure or material (metal in this case), the amount of electricity can be controlled.

A low resistance electrical circuit is created between the anode and cathode and two metal surfaces, with water acting as a medium to provide cathodic protection to the inside surface of the tank. This protective current keeps metallic ions at the cathodic surface (metal tank) from corroding.

If the tank material is anodic, rapid failure might occur. As the heater tank is a cathode and slows down corrosion, manufacturers add another metal element - the water heater anode rod. The rod is made with a higher current potential than other metal elements in the heater to allow galvanic current to flow from the rod.

Water heater anodes send electrons to the metal tank and release positive hydrogen and metal ions into the water. During this process, the anode rod starts depleting, sacrificing itself to protect the tank and extend its life. This is why it is called a sacrificial rod or sacrificial anode.

The life expectancy of this protective element depends on several factors such as water quality, material, usage, and maintenance, and it could be from 5 to over 10 years but depends on maintenance and proper installation.

Reasons to change a water heater anode rod: Common problems and solutions

Two of the main issues connected to the anode rod function are smelly water or hydrogen sulfide odor and tank corrosion.

Smelly water, known as the rotten egg odor is often found in water wells, where anaerobic bacteria are the leading cause. Some plumbers recommend removing an anode to fix this problem, but this leads to the second problem - unprotected metal tank and corrosion. Here is some good info on how to deal with the rotten egg odor.

Note: Created hydrogen gas might form a high concentration which is explosive. You should be very cautious there, and that is why professional anode replacement and installation is recommended.

One of the simplest and most effective ways to remove the bad odor from the tank is by flushing the tank.

Types and differences of water heater anodes

Magnesium anodes

Standard water heaters are commonly equipped with magnesium anode rods, identifiable by the weld bead on the plug. These anode rods are highly effective in protecting the water heater tank against corrosion in areas where the water is not hard but is soft.

However, in areas where the water is hard, the magnesium anode rod will not last very long, typically only a couple of years. The advantage of using magnesium anode rods is that they corrode faster than the iron used for inner water storage tanks, thus sacrificing themselves to protect the tank.

However, the disadvantage is that the rapid corrosion can sometimes lead to a buildup of sediment in the tank, which can decrease the efficiency and lifespan of the water heater.

Aluminum anodes

To combat the effects of extremely hard water and high conductivity, an aluminum-zinc anode rod may be a more suitable solution.

However, it's important to note that if you live in an area with a high pH level of 8 or above, the water can react with the aluminum anode rod and result in excessive amounts of aluminum hydroxide. This gel-like substance can build up on the rod and at the bottom of the tank, causing crackling, popping, and gurgling noise.

Zinc anodes

If you are experiencing a rotten egg odor coming out of the hot water tap, which is the most common complaint associated with the anode, you can consider installing a zinc anode rod. This might be a good option when replacing an already depleted or dissolved anode as it is not typically factory-installed.

Zinc anode rods are actually aluminum rods with a small portion of zinc. The proportion is typically 1:10, with zinc added to help fight the sulfur (rotten egg) smell coming from water.

If you are using a chlorination procedure to eliminate various bacteria causing the odor, it is recommended to remove the anode rod and replace it when the procedure is completed.

Flexible anodes

If you're dealing with limited overhead clearance or a tight installation space, a flexible anode rod might be a better option. This type of rod is divided into several smaller sections or links, making the whole rod bendable instead of one solid piece. The added flexibility makes it easier to install the anode rod in confined areas where a traditional straight rod may not fit.

Powered anodes

Some water heaters, such as AO Smith Effex, are equipped with a non-sacrificial powered anode, which is a better solution than the previously mentioned options as it can last a lifetime and provide higher performance in any water condition.

The powered anode is plugged into an electrical outlet and, since it does not deteriorate, it can be a permanent replacement (unless damaged). It is also a fix for smelly odor from the heater when using a a water softener and has a smelly odor from the heater.

Some manufacturers, like Rheem, produce models such as the Marathon that don't have a water heater anode rod. In this case, a metal tank is replaced with a plastic one.

How to change a water heater anode rod: Installation tips

The lifespan of a sacrificial anode rod depends on various factors, including water quality, usage, material, and quality. Typically, these elements can last about five years, or even longer in some cases, but it's recommended to remove them every two to three years for inspection. When using water softeners for sediment problems, be cautious as it can increase corrosiveness, leading to faster anode rod deterioration and reduced heater life.

Water heater anode rods are screwed into the top of the heater with a 3/4" hex head screw. For standard products with a warranty of up to six years, you will usually find one element, but for heaters with longer warranties, you may see more.

The hex head nut can be visible (exposed) or hidden, often located beneath the plastic cover on the top.

The best time to replace a water heater anode rod is when the steel core is exposed more than 6 inches from either end or when the middle of the rod is exposed, or when the diameter is less than half of the original size.

Don't wait until the rod is fully depleted to avoid potential damage to the tank.

Required tools

• 1-1/16", 6 or 12-point socket wrench
• Ratchet or breaker bar
• Pipe wrench

Step-by-step instructions

To replace or remove the water heater anode rod, follow these steps:

• Step 1: Shut off the power to the heater. For electric heaters, turn off the circuit breaker. For gas models, turn off the gas valve.
• Step 2: Turn off the cold water supply at the main water valve.
• Step 3. It is recommended to drain a few gallons of water from the drain valve at the bottom of the heater.
• Step 4: Attach a garden hose to the drain valve and route it to an open drain. Open a nearby hot water tap to vent the heater for draining. Drain to the point below the outlet connection nipple. If there is not enough overhead clearance, it may be necessary to drain the whole system and tip the unit to provide enough space for proper installation.
• Step 5: Close the drain spigot and remove the hose.
• Step 6: Locate the anode rod and its hexagonal plug found on top of the heater.
• Step 7: Use appropriate tools to remove the water heater anode rod by turning it counterclockwise.
  
• Step 8: Apply Teflon tape on the fitting threads to seal them tightly.
• Step 9: Once you replace the anode open the cold water supply to the water heater to fill the tank. Check the connections for leaks. If everything is okay, turn the power back on, including the gas valve.

Or, use this video, provided by Rheem:

What to do if an anode rod is stuck (seized) and won’t come out?

If the anode rod is stuck and won't come out, don't worry. There are several tools you can use to remove it. You can loosen the threads of the rod by using an air-driven impact hammer and wrench, a breaker bar, or even a blowtorch and heat, but be cautious not to damage the rod and threads.

To remove the seized anode rod, do not use rust dissolvers such as WD-40, muriatic acid, or any other type of penetrating oils, as they might get inside the tank and contaminate the water.

Tip 1: First, try to tighten the anode just a hair, and then apply all your force in the opposite direction (counterclockwise). This will break the corrosion on the threads. Some plumbers have reported that it works.

Tip 2: You might also have to secure the tank using a ratchet strap and wedge block as an anchor. This will prevent the heater from spinning counterclockwise while applying force in the same direction. The idea is to apply all the torque into the rod threads, prevent the heater from moving, and at the same time protect the wall from damage.

Note: If the water heater is over 15 years old, you might want to consider replacing it because an anode might be corroded (as well as other elements). Rust on the threads will make the rod challenging to remove; rust flakes can also penetrate the tank and contaminate water, or even worse, corrosion can cause leaks.

Can an anode rod be cut, and does the length matter?

If you are trying to replace an old anode rod, but don't have much space above the water heater to remove it freely, you can either bend or cut the anode. Once you cut it, make sure that the bottom end doesn't fall back into the tank.

If you are installing a new solid rod, make sure to use one of the same length as the old one. If you have purchased a longer one, cut it to the length of the previous (original) one. It is recommended to cut it to a length that provides a clearance of a few inches from the bottom of the heater.

Instead of buying a long anode and cutting it to the correct size, a better idea is to get and install a flexible anode.

Does length matter?

Of course, it does, because the longer it is, the more it can sacrifice and last.

Summary

According to experts, the anode rod is one of the most important elements in tank-type water heating systems. If you don't change the anode rod when recommended, your water heater might stop functioning properly.

You can buy an anode rod cheaply, but keep in mind that it plays a vital role in the lifespan and performance of your heater. While quality and professional installation are essential, regular maintenance and service also contribute to how long the anode will protect the tank. That's why it's necessary to contact a licensed plumber.

Note: If you remove a water heater anode rod for any reason, it will void the warranty and affect the tank's longevity.

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