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Why The Protective Anode In Your Hot Water Heater Should Be Replaced

By:Darrell Young

Did you know that every month tens of thousands of hot water tanks burst prematurely due to corrosion causing severe water damage to property both indoors and outdoors, yet this can easily be avoided?

There is one simple thing you can do NOW to protect your hot water tank from the destructive effects of corrosion on your tank.

It's Anode replacement!

So, what is a Sacrificial anode?

An Anode is a specially designed magnesium rod that is installed inside your hot water tank and is designed to protect your hot water tanks steel cylinder from severe corrosion resulting in premature tank failure.

Every steel cylinder hot water tank comes with one and will only last about 4-5 years, but once your Anode is depleted there is nothing to stop the destructive effects of corrosion on your tank.
Why is an anode necessary?

Steel cylinder type hot water tanks have a glass lining to help protect against corrosion. The glazing material is quite brittle and the continuous expansion and contraction of the tank every time the water is heated and cooled causes the development of thousands of hairline fractures.

As these fractures appear, water comes in contact with the steel walls on the inside of the tank and the glass lining starts to deteriorate exposing the steel cylinder to the effects of corrosion. The anode reacts with this exposed steel, sacrificially corroding in its place.

How Anodes work:

Anodes are manufactured from special grades of magnesium to suit various water conditions and they protect steel by a sacrificial electro-chemical action. Magnesium is electro-negative relative to steel. When a magnesium anode is fitted to a steel tank filled with water, a very small current will constantly flow through the water between the anode and any exposed steel area on the tank wall. The circuit is completed through the tank back to the magnesium anode.

This protective current is produced by the magnesium releasing ions, and this results in corrosion in the anodic area. The magnesium (the anode) corrodes instead of the steel tank (the cathode). This principle of electrolytic corrosion control is called cathodic protection. Because cathodic surfaces cannot corrode, the steel tank is protected against rusting.

The heater manufacturers themselves recommend anode replacement in their owners' handbooks. Dux Water Heaters recommends replacement at five-yearly intervals and the manufacturer of Rheem and Vulcan brand water heaters recommends seven or eight years for its standard range and ten years for its long life models.

Other than Call The Plumber, these relate to US conditions so they are totally unbiased and they all confirm the importance and necessity of anode replacement in water heaters.

"Following a schedule of timely replacement of the sacrificial anode in your hot water tank will double, or even triple, its life."

Which types of heaters use an anode for corrosion protection and which ones do not.

All gas, electric and solar mains-pressure water heaters with a vitreous enamel or bonded ceramic coating utilize a sacrificial anode to provide additional corrosion protection.

Which heaters do not have an anode?

1. Gravity Fed Tanks Located In The Ceiling.
These are mostly found in older homes and they are rarely supplied new nowadays due to the fact that the hot water supply relies on gravity alone and as such, it's not very satisfactory for showering.

2. All Types Of Instantaneous Gas Heaters.
These are small, wall-mounted heaters which heat the water as it passes through them. Common brands are Bosch, Pyrox, Zip, Rinnai Infinity and Rheem Integrity.

3. Stainless Steel And Copper Storage Type Heaters.
These heaters look similar to the ones that do require an anode. They are generally the same size and shape but the tank is either stainless steel or copper and does not require an anode.

Brand names to look out for with a stainless steel tank are Aqua-Max gas heaters and Edwards and Beasley, in both electric and solar types. Heaters with a copper tank include Lango Copperfied and Rheem Coppermatic. These copper tanks are no longer available due to the high cost of manufacture.

You should check with the manufacture of you tank and local water conditions on when to inspect your anode. For hot water heaters in the Sydney metropolitan area, we recommend the anode should be inspected between five and seven years of age.

Under average conditions, it is normal that an anode will require replacement at these times. Even if there is apparently still sufficient magnesium left, it is often heavily coated with mineral deposits and it is therefore unable to provide effective protection for the heater's tank.

If your hot water tank is over 5 years old then you need to replace your anode NOW!

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Article keywords: Blocked Drains, Plumber, Plumbing

Article Source:

Darrell Young is a third generation master plumber running his own plumbing
company since 2001. For more information and plumbing tips visit his web site at

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