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Powered Anode Rod vs Sacrificial Anode


Sacrificial rods are inexpensive and don’t need electricity to run, but they need to be replaced roughly every 3-5 years. Different types of these rods perform better in different types of water. Powered rods are expensive, but they tend to last 20 years, work will all types of water, and reduce limescale buildup.

Powered anode rods may seem like the perfect choice for anyone on the market for a new anode rod—no maintenance, long lifespan, and good performance. All these claims might sound a bit too good to be true. Taking into account their high price tag, it is no surprise that you would want to know more about these rods before you make the purchase.

You’re in luck! This article will show you how they compare with the regular anodes in their price, maintenance, performance, and more.

How Do They Work?

An anode rod is a device required by most water heaters that have tanks. Typically, new water heaters will come with a sacrificial anode rod already installed. Their purpose is to limit the amount of corrosion that the water heater’s tank is subject to. 

They can extend the water heater’s lifespan and can prevent the water heater from bursting open.

The master repairs the boiler with anode rod in water heater tank

Powered Anode Rod

Corrosion is an oxidative process that involves the loss of electrons from a substance. A powered anode rod supplies a small amount of current to the water heater, which halts the loss of energy (in the form of electrons) from the metals contained in the water.

As the metal tank is no longer losing electrons, the iron does not develop a positive charge to which the partial negative charge of oxygen atoms in water molecules would be attracted. Thus, the oxidative process of corrosion is prevented. 

Furthermore, the electrical current disrupts the attachment of minerals to the tank, preventing limescale build-up.

The system is made up of a titanium anode and a current rectifier that needs to be plugged in. Because the rod is titanium, it does not corrode, unlike a sacrificial anode rod. 

For a more in-depth explanation, you can read my article: How Do Powered Anode Rods Work.

Sacrificial Anode Rod

A sacrificial anode rod is made up of a metal rod, usually magnesium or zinc, that corrodes over time in place of your water heater tank. The rod corrodes until only its core remains.

The reason it corrodes instead of the steel tank is that metals are not all equally reactive with oxygen. Their degree of reactivity is predictable to the point that metals are arranged into something known as the reactivity series.

Both magnesium and aluminum are higher in the reactivity series than iron because they react more readily with oxygen and will preferentially corrode.

Thus, the rod will keep protecting the water heater tank until it becomes completely degraded.

There Are Several Types of Sacrificial Anode Rods

The types of sacrificial anode rods vary by the type of metal they utilize. These metals include magnesium, aluminum, and aluminum/zinc alloys.

The metals are chosen due to their reactivity since they must be more reactive than the water heater tank metal.

The differences between different sacrificial anode rods include price, their lifespan, whether they add extra benefits to the water or whether they perform better in soft or hard water.

Comparing Performance

Based on the water content as well as any specific problems the water might have, such as smell, a sacrificial anode rod may work better than a powered anode rod and vice versa. 

A man holding a anode damaged from corrosion. In the background the boiler and a view of the lawn. Close up. comparing

For sacrificial anode rods, specific types (magnesium, aluminum, etc.) may work better than others. 

Hard Water

Hard water contains more minerals and leaves more deposits than other types of water. 

Because of this, the anode rod suited for hard water would have to be able to withstand these high mineral concentrations. This would include both aluminum sacrificial anodes and powered titanium anode rods. 

Powered anode rods have the added advantage over aluminum rods of being able to reduce limescale accumulation associated with hard water, while sacrificial anode rods are less capable of this.

Magnesium sacrificial anode rods are not well-suited for hard water because they are too reactive and would corrode more quickly than aluminum rods.

Softened Water

While hard water has more minerals dissolved in it, soft water contains more corrosive substances. 

Magnesium is highly reactive, so it would be able to handle the high amounts of corrosive substances, although it would need to be replaced more frequently.

An aluminum rod, on the other hand, would not be able to keep up with the number of ions in the water and the tank would start to corrode in addition to the rod. Yes, the rod would “last” longer, but it will not fully achieve its purpose and the water heater tank’s life would be shortened.

As far as how a powered anode rod would fare, they would handle the conditions just fine but with no added advantages, unlike magnesium rods, which might add health benefits to the water.

When deciding between magnesium and powered anode rod for softened water, it is wise to consider costs, durability, and maintenance.

Smelly or Well Water

The best type of sacrificial anode rod for smelly or well water would have to be aluminum/zinc anode rods. 

The inclusion of zinc handles unpleasant smells. Aluminum would also help in the case of well water since it often has higher levels of dissolved minerals, which would liken well water to hard water.

Powered anode rods would also be good in a smelly/well water scenario, as most models also claim to be able to kill the bacteria that produce the smell.

Powered Anodes Have a Long Lifespan

Sacrificial anode rods are literally designed to wear away over time. While aluminum rods tend to last longer than magnesium ones, you are still only looking at an effective lifespan of 3-5 years.

As such, powered anode rods are clearly triumphant when it comes to lifespan. Some popular models are made to last more than twenty years!

If for whatever reason, they do not, and you have complied with the terms of the warranty, your powered anode rod could be replaced for free within the first twenty years. Sacrificial anode rods do not come with a warranty.

Maintenance and Installation of Anode Rods

Sacrificial Anode Rods Require More Maintenance

It is safe to say that sacrificial anodes need to be replaced every five years or so. If you have hard or softened water, then this might be reduced.

In order to check the state of the rod, you must turn off the water heater and at least partially empty the tank since the rod is immersed in the water. 

illustration of anode rods, new anode rod, 50% depleted, 75% depleted, completely depleted

If your anode rod is more than 75% (some experts even say 50%) corroded, it’s a good idea to replace it. 

As previously discussed, your powered anode rod is made from a non-reactive metal, so you will not need to replace it so often (possibly not even at all).

Powered Anode Rods Require an Electrical Outlet

By now you know that powered anode rods utilize a small current in order to protect against corrosion. The current rectifier must be plugged into an electrical outlet for this current to be produced. 

Because of this need, the powered anode needs an electrical outlet just like the water heater does. This may complicate things if the nearest outlet is already full and wires are not long enough to accommodate for relocation.

installing of water heater, anode rod

On the other hand, all you need to remove and install a sacrificial anode rod is:

It will not require any additional wiring or extension cables, which is good because water and electricity are a volatile combination.

Powered vs Sacrificial Anode Rod: Comparing Cost

Cost to Buy

  • Powered anode rods can cost up to $170 dollars. On the low side, they are still about $145. 
  • Magnesium sacrificial rods often only cost about $15 to $30.
  • Aluminum rods are often around $15.
  • Aluminum/zinc anode rods can cost from $20 to $45. 

As you can see, the powered anode rods can be up to ten times the price of sacrificial rods.

Cost to Maintain

Not only is the initial price of the powered anode rod far higher than the one of sacrificial anode rods, but you must also account for the price of the electricity the powered rod will use.

Luckily, this number should be too significant. According to Corro-Protec, their anodes cost less than $2 to run per year.

Corro-Protec™ Powered Anode Rod for Water Heater, 20-Year Warranty, Eliminates Rotten Egg/Sulfur Smell within 24 hours, Stops Corrosion and Reduces Limescale, Electrical Anode Rod Made of Titanium

On another note, the need to replace the sacrificial anodes more often can significantly add up to the cost.

For example, if you buy the higher end ($45) aluminum/zinc rod and must replace it four times within the twenty-year period of a powered rod, you’d pay $180 for four replacement rods.

This is more expensive than the most expensive powered anode rods, and that presumes that you will replace the rod yourself. If you decided to hire a professional to do it for you, the final replacement cost would be even higher.

Table Summary

Powered Anode RodsSacrificial Anode Rods
They can last up to 20 years.They can last a range of 1-5 years.
The cost can be up to $170.They often cost about $15-$45. 
The rod does not corrode. The rod corrodes and must be replaced about every 5 years.
They are suited for hard water and maybe soft water.Depending on the type, they can be suited for hard, soft, and well/smelly water.
The current rectifier must be plugged into an outlet.No electric charge is needed. 

Sources

https://plumbingnav.com/water-heaters/anode-rod-by-water-type/#:~:text=Aluminum%2Fzinc%20anode%20rods%20work%20best%20for%20hard%20water.&text=Aluminum%20anode%20rods%20possess%20higher,in%20contact%20with%20hard%20water.

https://www.corroprotec.com/powered-anode-rod/

https://www.hydrosolution.com/en/guide-and-tips/the-sacrificial-anode-what-is-it-and-when-should-you-replace-it/#:~:text=The%20sacrificial%20anode%20is%20an,in%20place%20of%20the%20tank.

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