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What Does the Anode Rod in My Water Heater Do?

19 Sep 2020
Water heaters are essential to modern life. However, most of us have very little idea of how they work, beyond the basics. We know that water flows into the cylinder from the mains, that it is heated, and that the temperature is maintained by good insulation around the cylinder, but that’s about it. Most of the other components are mysteries to us. For instance, what’s an anode rod and what does it do?

What Is an Anode Rod?

You may hear it called an anode rod, or a sacrificial anode rod, but they are both the same thing. It’s a metal rod that’s extended into the cylinder of the water heater. It serves just one purpose – to attract corrosive elements and prevent them from causing damage to the cylinder walls.

An electric current flows through the rod, charging it, and attracting particles with the opposite charge. As the particles collect, the rode corrodes, eventually succumbing to the damage and needing to be replaced.

What Is an Anode Rod Made From?

Anode rods are made from metal, but different metals can be used. You will find they’re made of either magnesium, aluminium, or zinc. Each metal offers something a little bit different.

Magnesium – Magnesium is the best-performing metal for anode rod construction, but it’s the least durable. It generates around 1.6 volts in the cylinder but may need to be replaced every year if your water is particularly hard or soft.

Aluminium – Aluminium generates 1.1 volts and is the middle ground when it comes to anode construction. You’ll need to inspect it annually, but usually, they will only need to be replaced every five years or so.

Zinc – This is the lowest performance material, generating just 1.05 volts. It has a lifespan pretty comparable with aluminium.

What Happens When an Anode Rod Fails?

So, what happens when you anode rod eventually reaches the end of its lifespan? Does your water heater stop working? No, but the process of failure is accelerated. The anode rod prevents corrosive agents from attacking the walls of the cylinder. Without it, those corrosive elements go to work eating away at the inside of your cylinder, eventually causing serious problems, and, ultimately, failure.

Signs of Anode Rod Failure

How do you know when your anode rod has failed? Ideally, you’ll have a water heater maintenance service inspect everything once per year. This is the only way to guarantee that you are able to replace the rod before it fails completely and extend the lifespan of your water heater.

However, there are signs you can look for that may indicate your rod has already failed. It may or may not be too late to save the cylinder. Some of these signs include:

  • Popping sounds during water heater operation
  • Clogging faucet aerators
  • Slimy gel on faucet aerators
  • Water is warm but not as hot as it used to be

Concerned that your anode rod might be about to fail, or have already failed? Contact EasyFlow to schedule an inspection from one of our water heater specialists.

EasyFlow can send an engineer to you if you’re located in Greater Manchester, Warrington, Liverpool and Chester.


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