ANODE: What are we talking about?

You may have seen or heard of the anode in a water heater. It’s one of the essential components of a water heater, and contributes directly to extending its service life.

What is an anode in a water heater?

The anode in a water heater is a device that protects the tank from corrosion. The anode is made of 100% magnesium and resembles a cylinder whose diameter and length depend on the water heater’s capacity.

What is the role of the anode?

Water heater tanks are made of either enamelled steel or stainless steel.

The magnesium anode provides passive protection. Magnesium particles attach themselves to the enamel, plugging its pores and protecting it from water attack. Also known as a “sacrificial” anode, it disappears after a certain period of time as a result of this electrolysis phenomenon. The anode corrodes in place of the tank metal.

When should the anode be changed?

It is therefore very important to change it regularly before the water heater is no longer protected from corrosion. When anode wear reaches 75%, we recommend replacing it. If the magnesium anode has shrunk significantly from its original size, it’s time to replace it.
The service life of a magnesium anode is generally between 3 and 5 years. However, this may vary according to water hardness. Regular checks on the condition of the magnesium anode are therefore necessary (every 2 years).

What are the most important technical features of an anode?

Mounting :The anode is usually mounted to the water heater flange, on a threaded rod. It is therefore important to know the diameter of the thread. The most common are M8, M6 and M5.

Magnesium bar diameter :As the anode is often close to the heater, or even mounted on the heater, knowing the diameter guarantees a fitting compatible with the water heater flange and resistance.

Magnesium bar length :As with diameter, length is a key factor in ensuring correct installation in the water heater and the right amount of magnesium to protect the tank.

How to check an anode?

The method is to remove it to see if it is damaged or covered with deposits. If it’s badly worn or damaged, it needs to be replaced.

1. Disconnect the water heater’s electrical circuit and turn off the water supply.
2. Drain your tank using the drain valve or the sanitary safety group.
3. Carefully remove the anode using a suitable tool. It’s usually located near the thermostat stem, and close to the heating element. The anode can be accessed by dismantling the flange that supports the heater, thermostat and anode assembly.

4. Visually inspect the anode for damage or deposits.
5. If the anode is badly worn or damaged, it’s time to replace it.
6. Reinstall the anode, reconnect the electrical circuit and reopen the water supply.