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Do All Water Heaters Have Anode Rods

Anode rods are not an easy concept to understand logically, although it does make sense physically. A metal rod that you place in your water heater that is meant to fail and disintegrate into nothing? Anode rods play a key role in improving the lifespan of a water heater, but only certain water heaters need them.

Below I will take you through a number of different water heaters and speak about whether or not they need anode rods and why. At the end of the article, I include a table summary for quick reference and links to more detailed articles about each of the water heaters’ anode rod needs.

Whether or not a water heater needs an anode rod is determined by style and material. Most other factors (e.g., fuel source, brand) do not affect whether or not a water heater needs an anode rod. Glass-lined steel tank-style heaters need anode rods. Stainless steel, plastic, or tankless heaters do not.

Not All Water Heater Need Anode Rods

An anode rod is an approximately 2 ft metal rod that extends from the top of a water heater (known as a geyser in some countries) into the body of the tank. It is made of metals such as magnesium, aluminum, and zinc, wrapped around a steel or stainless steel core.

The metals in an anode rod are meant to corrode over years of being submerged in hot water. The reason you want an anode rod to corrode is so that the walls of your tank are spared from corrosion.

There are also powdered anode rods, which use electrical impulses to intercept the corrosive elements in water.

Kohree Aluminum Zinc Anode Rod 44", Water Heater Protection Hex Head Flexible Anode Rod Includes 1 Tape Water Heaters Tank 3/4" NPT Threads for Rheem, Reliance, Richmond, Kenmore, State, GE

Certain styles of water heaters are naturally less vulnerable to corrosion than others. For example, water heaters made of stainless steel do not corrode over time and therefore do not need an anode rod. In addition, a water heater only needs an anode rod if it has a tank and is made of a material that is at risk of corrosion.

Tankless Water Heaters

Tankless water heaters do not require anode rods. They may be made in a variety of materials with varied fuel sources, but none of these varieties will require an anode rod.

Anode rods serve the purpose of sacrificing themselves to subvert the corrosive effects of water away from the water storage tank’s walls. Within a tankless water heater system, the anode rod’s job is not necessary because there is no tank present.

A tankless water heater involves pipes that draw up water and run through a heat exchange system. Water is heated directly as it goes through the pipes rather than sitting in a tank to heat up. This allows the user to draw hot water directly as needed, which makes them much more energy-efficient.

While corrosion is possible if leaking occurs within the pipe system of a tankless water heater, it is less apparent since there is not the element of sitting water.

Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray

State Water Heaters

Glass-lined (regular) tank-type State water heaters have anode rods. Some come with the option of a powered anode as opposed to a sacrificial anode rod. Tankless water heaters do not require anode rods, and State’s tankless range are thus without anode rods.

State is a leading American water heater manufacturer, not a type of water heater itself. This brand has been around for about70 years and produces a variety of different types of water heaters.

Since State produces several different types of water heaters, the answer for whether State water heaters require anode rods is both yes and no. Certain types of water heaters, namely tank-style, require anode rods, while other types, namely tankless, do not require them.

State produces standard glass-lined tank-style water heaters, and this style requires an anode rod because it has a tank for storing water where corrosion will occur unless a sacrificial anode rod is present. For this reason, State’s regular tank-style water heaters require anode rods.

State also produces tankless water heaters. These do not have a storing tank where water sits and creates corrosion, so they do not require anode rods to fight corrosion. State’s tankless heaters are therefore anode-less.

Some State Water Heaters Have Powered Anode

Regular anode rods deplete, and in order to keep protecting your water heater, they need to be changed regularly—we have already covered that! Their lifetime depends on the hardness of the water, the presence of a water softener, and the amount of water going through the heater.

But if you are planning to buy your new State water heater and you don’t really want to worry about replacing the anode rod, you can look into their models that come with a powered anode. These anodes are non-sacrificial, meaning they do not degrade and thus can also better deal with different water conditions and provide the heater with enhanced protection.

State Water Heaters have quite a few heaters with the powered anode in their selection. For example, they have 80-gallon Premier Hybrid Electric Heat Pump. They also offer a plethora of gas tank heaters that have powered anodes. Their capacity ranges from 40 to 75 gallons.

On top of that, the brand gives you an option to buy the powered anode system independently. It is suitable for electric and gas 30–120 gallon heaters, regardless of whether they are residential or commercial.

This system is superior to different ones because it allows the anode to adjust to current conditions and provides the heater with as much or as little protection as is required at any given moment.

Rheem Water Heaters

Rheem is another popular water heater manufacturer. They sell water heaters in a variety of styles including tank-style, tankless, and hybrid water heaters. They sell each of these styles in several variations.

Rheem has been an innovator of the hybrid water heater, introducing the style in 2009. This style blends the fast water retrieval of the tank-style water heater with the improved energy efficiency of the tankless style.

Rheem tank-style and tankless water heaters follow the same guidelines as general tank-style and tankless water heaters for if they require anode rods.

Their tank-style water heaters require anode rods to combat the effects of corrosion, except when they are made of more resistant materials.

Rheem’s Marathon tank-style water heater does not require an anode rod since the tank is made of polybutene, a plastic material that does not corrode. This water heater comes with a lifetime warranty, like other brands’ stainless steel models.

Their tankless models do not require anode rods. However, their hybrid-style water heaters require anode rods since they are designed with a holding tank for water.

Stainless Steel Water Heaters

Stainless steel is a premium material for tank-style water heaters since it resists corrosion and lasts a long time.

Stainless steel water heater tanks do not require an internal coating of glass, which makes them more lightweight and durable.

Stainless steel is made of a steel alloy that must include at least 10.5% chromium. This chromium is the source of stainless steel’s corrosion resistance since it reacts with air to create a protective barrier on the steel.

Rheem G100-200 LP Propane Universal Commercial Water Heater, 100 Gallon

Due to this resistance to corrosion, stainless steel water heaters do not require anode rods even though they do hold sitting water. The ions in the water are not at risk of corroding the metal of the tank.

Stainless steel water heaters are also highly immune to the build-up of minerals that commonly occurs within glass-lined water heaters. Since hard water exacerbates this mineral build-up, stainless steel water heaters are recommended in homes with very hard water.

Glass-lined Water Heaters

Glass-lined water heaters have anode rods. The tanks are made of steel lined with glass. The glass does protect the tank against corrosion, but it is vulnerable to cracking and leaking, so anode rods are still required. The glass also helps to insulate the tank, making it more energy-efficient.

Purpose of Glass Is to Protect Tank From Corrosion

Glass lining is one of the safety features of water heaters. It serves as a barrier to stop the water from being in constant direct contact with the steel water tank. Therefore, the lining provides the tank protection from corrosion to some extent.

It also acts as an additional insulation layer that helps the heat to stay within the tank, making it more efficient in its function.

However, in order to obtain the ultimate protection from rust, any glass-lined water heater also needs an anode rod. Why?

Glass Lining Is Not Perfect Barrier

Glass lining doesn’t last very long when left on its own as the sole source of rust prevention. This is due to its somewhat fragile nature.

With time and heavy use, it begins to split and crack, allowing the water to come in contact with the outer layer of the tank and eventually causing it to corrode. The lining could also get damaged during heavy transportation or during unprofessional heater installation.

Holdrite 30-SWHP-M Ceiling Mounted Suspended Water Heater QuickStand with Drain Pan, 24 Inch x 24 Inch x 4 Inch

Even small cracks in the lining could cause leaks into the metal casing of the tank, decrease the heater’s efficiency, or ultimately damage the water tank. This is why the glass-lined water heaters also need an anode rod to protect them from rusting.

When the water starts getting through the cracks in the glass lining, an anode rod acts to stop corrosion and ensure the efficient run of the heater. Without the rod, the lifespan of the heater would be radically shortened, and the quality of the water could decrease.

However, keep in mind that not all glass linings are created equal and that some are more durable than others. Generally, it depends on the manufacturer, so it is good to opt for established reliable brands, like State or Rheem.

Either way, you should still invest in a good anode rod as well, but be careful of the length. If your anode rod is too long for your water heater, it can be the cause of damage to the inner glass lining.

Is Glass Lining Pointless?

Just because an anode rod is required, it does not mean that the lining doesn’t have its place in the water heaters. It still plays a vital role in the heater’s safety and efficiency.

We can say that the rod is the only thing protecting the tank from corrosion when the lining cracks. But we should also point out that the lining is the only thing preventing the water from being in continuous, direct contact with the tank, thus protecting it from corrosion even when the rod deteriorates.

The truth is that the glass lining and the anode rod both need each other in order to prolong the water tank’s lifespan and provide it with maximum rust protection.

If the tank didn’t have any lining protecting the majority of its surface, the anode rod would most likely not be able to prevent rusting of the whole tank. It would probably deplete very quickly, but most importantly, it would not work efficiently enough to protect the tank and stop leakages.

On top of that, the glass provides additional insulation, so without it, the heater would be losing a lot of heat, causing it to be a lot less efficient.

Indirect Water Heaters

Indirect water heaters are a variety of water heater that uses less energy than traditional gas or electric water heaters by involving a heat exchange system. Depending on the material it’s made of, it may or may not require an anode rod.

An indirect water heater involves a heating system with a boiler that externally heats up fluid. This fluid then circulates through pipes a system in the bottom of the water heater tank to heat the water.

Eastman 60022 60022/DET-5 2 Gallon Expansion Tank, White

Indirect water heaters have a storage tank for heating water through heat exchange. This tank requires an anode rod to fight corrosion unless it is made from stainless steel.

If the holding tank is made from stainless steel, then the indirect water heater will not require an anode rod since the material will be resistant enough to corrosion.

Gas Water Heaters

Gas water heaters sometimes require anode rods and sometimes do not. Many different types of water heaters are available in the gas-powered variety. There are tank-style and tankless gas-powered water heaters. I have not found hybrid gas-powered water heaters.

Additionally, indirect water heaters may technically use gas as the power source for the burner, but I will not include them here since they have been covered more in-depth above.

The power source is not the main factor that determines if a water heater needs an anode rod. The factors that determine whether a water heater requires an anode rod are style (whether it is tank-style or tankless) and material (if its tank is glass-lined or stainless steel).

Glass-lined tank-style gas water heaters require anode rods because the tank will face significant corrosion without a sacrificial anode rod to protect it. However, stainless steel tank-style gas water heaters do not require anode rods since stainless steel resists corrosion.

Tankless gas water heaters do not require anode rods because they are not as vulnerable to corrosion as tank-style water heaters since they do not have sitting water.

Electric Water Heaters

Electric water heaters with steel water storage tanks have anode rods. These are needed for the continued functioning of the heater as they corrode instead of the tank. If the electric water heater tank is stainless steel, the unit won’t have an anode rod. Tankless electric water heaters don’t have anode rods.

Electric water heaters are the alternative to gas-powered water heaters. Once again, the power source does not determine whether a water heater does or does not need an anode rod. Style and material are more important because these factors have to do with how vulnerable or resistant the unit is to corrosion.

Tank-style water heaters are highly vulnerable to corrosion unless they are made of stainless steel, and tankless water heaters are not as vulnerable to corrosion as tank-style.

Stiebel Eltron 233219 2.5 gallon, 1300W, 120V SHC 2.5 Mini-Tank Electric Water Heater

Since they are constantly holding sitting water within their tank, the standard glass-lined tank-style water heater unit requires an anode rod whether it is powered by gas or electricity. Tank-style water heaters can also come in stainless steel, which is resistant to corrosion. For this reason, stainless steel tank-style water heaters do not require an anode rod no matter the power source.

Tankless water heaters do not require anode rods, no matter the power source, since they do not hold water for a prolonged period of time within the unit.

Which Water Heaters Need Anode Rods: Table Summary

Water heaterAnode rod required
Tankless water heaterNo
State water heaterOnly tank-type
Rheem water heaterOnly tank-type
Stainless steel water heaterNo
Glass-lined water heaterYes
Indirect water heaterSometimes
Gas water heatersSometimes
Electric water heatersSometimes

When you purchase a new water heater and that water heater is of a type that requires an anode rod, then you should get the first anode rod free with the heater. The type of anode rod that will work best for you will depend on the quality of your water.


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