A powered anode rod relies on current to stop corrosion inside the water heater tank. the powered anode will protect the water heater as long as there is some current inside the tank. If current goes out, protection will reduce until current is coming back.
Traditional magnesium anode rod relies on the rod itself to reduce corrosion. Corrosion will attack the rod before attacking the tank. When the rod is over 60% depleted, the water heater rust and lifetime are badly affected. Those are also know as hex head anode rod.
Cathodic protection is used to mitigate corrosion damage to active metal surfaces. Cathodic protection is used all over the globe to protect pipelines, water treatment plants, above and underwater storage tanks, ship and boat hulls, offshore production platforms, reinforcement bars in concrete structures and piers, and more. There is two types of cathodic protection : Sacrificial and Impressed Current (Powered Anode).
Sacrificial VS Powered Anode
Sacrificial Anodes are highly active metals that are used to prevent a less active material surface from corroding. Sacrificial Anodes are created from a metal alloy with a more negative electrochemical potential than the other metal it will be used to protect.
traditional sacrificial anodes need to be replaced every couple months to make sure your tank is protected against corrosion.
The sacrificial anode will be consumed in place of the metal it is protecting, which is why it is referred to as a "sacrificial" anode.
Powered anode rods are non-sacrificial rods (meaning they don’t degrade like a normal anode rod) which use control modul that supply electrical pulses to deal with corrosive elements in your water. Overall, there are quite a few advantages to using powered anode rods. They don’t degrade, prevent smelly water, and protect your hot water heater from corrosive elements in the water no matter your water conditions.
Since powered anode rods don't degrade like magnesium rod, they are designed to last for a very long time).
Are Powered Anode Rod Better ?
Both technology are working very well. However, it's like comparing an asphalt shingle roof to a sheet metal roof. Both will give you a good return from the start, but after a few years, the shingle roof will require inspection and replacement. More expensive, the sheet metal roof will give you peace of mind in the long term, and your neighbor will change the roof 2 or 3 times before redoing yours.
It's the same with the different types of anodes. Sacrificial anode will last between 1 to 2 years and powered anode will last up to 50 years.
In addition, powered anode rod will give you some benefits that you will never have with sacrificial anode.
How To Check Quality of The Powered Anode
The most important element is certainly the rod itself. Here, we are talking about the rod which will be in the water and which will send the electrons responsible for protecting against corrosion.
Made of titanium, the anode is covered with MMO (Mixed Metal Oxides) which will offer better conductivity. The MMO is made up of different metals and the manufacturers seem to want to keep their mixture confidential.
It is very important to check the width, length and thickness of the rod portion which is covered with MMO to conclude its service life. It is the most expensive part of the anode, which is why some manufacturers reduce the required quantity, which reduces the efficiency and the lifespan of the anode.
Power supply quality is also important since it's the part that supply the current to the anode. We have a complete page about powered anode rod quality : How to choose your powered anode rod.
Some power supply have a LED light to confirm that protection is active. You need to make sure the LED turn on ONLY if there's some current going inside the water heater. If the light turn on as soon as you connect the power supply to the anode and there's no water inside the tank, chances are the power supply light only means there's current at the outlet... Some high-end powered anode also offer audible alarm on the control module to let you know if the powered anode rod stops working.
Benefits of Powered Anode Rod
Powered anode rod are very popular because they stop the sulfur smell in hot water.
Current supplied by the powered anode will kill the bacteria that creates the smell in the hot water. This is the cheapest long-term solution available on the market.
Some people will tell you that bleach treatement is cheaper, but you need to know that it will only solve the problem for couple days. Other people are gonna tell you to change the magnesium rod for an aluminium rod, but it will work only in some specific cases.
Even if this advantage is not unanimous among distributors, it would seem that impressed current anodes can reduce the accumulation of lime.
The explanations gathered on one of the most popular site makes a lot of sense :
''The energy sent by the (...) imposed current anode is used to destabilize the calcium molecule found within the water, which has the effect of preventing the chemical reaction that normally creates calcite.''
Work With EVERYTHING
One of the biggest advantages of impressed current anodes is that they will work in all types of water. Whether you're plugged into city water or drawing water directly from a well, the anode will provide corrosion protection to your hot water tank.
The impressed current anode will be even more useful if you have a softener system that makes your water even more corrosive.