What is a sacrificial anode and how does it protect your water heater

The sacrificial anode is a metal piece attached to the inside of the tank that gives itself up by slowly reacting with oxygen and corroding first, over time. The metal inside the water unit stays safe. This is known as a redox reaction and simply transforms your hot water tank into a type of cell. When your hot water system corrodes the water may be red or brown in colour.

Sacrificial anode is a vital component of hot water systems, providing essential protection against corrosion. They are designed to be “sacrificed,” meaning that they will corrode and dissolve before any of the other components in the system.

sacrificial anode hot water system - corroded

Regular maintenance will extend the life of your water heater

The sacrificial anode is a long metal rod that extends inside the tank. It’s made from a more reactive metal such as magnesium, aluminium or zinc which will corrode instead of the other components of your hot water system. It attracts particles of iron, limestone or other minerals present in the water through an electrochemical process and corrodes in place of the tank. 

A sacrificial anode should be installed during installation or repair of all hot water systems – whether they’re residential or commercial – in order to provide adequate protection against corrosion damage. Sacrificial anodes come in different shapes and sizes and can be fixed onto many different types of heating systems including gas boilers, oil boilers, immersion heaters, solar heating systems and air source heat pumps. The higher level of galvanic protection offered by sacrificial anodes means that these systems will last longer and require less maintenance than those without them installed.

How does sacrificial anode prevent corrosion?

The anode is either made of zinc, magnesium or aluminium. It runs electrons to the inside metal surface which acts as the cathode. The presence of water in contact with the anode creates a current that draws electrons to the inner lining. The anode is slowly consumed while the cathode, or inner metal lining gains electrons and remains safe. This requires no added power input as the metal anode and cathode in water creates an electrochemical reaction. This is also known as an oxidation-reduction reaction.

Overview of the process:

  1. The anode is placed inside the hot water tank.
  2. The anode releases electrons, which are then picked up by other metals and act as a protective shield.
  3. The anode corrodes or is consumed.
  4. The metal of the sacrificial part is oxidized or becomes rust.
  5. The electrons are added to the cathode, or inner metal lining.
  6. The inside of the hot water system is safe as the anode sacrifices itself.
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. 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.

How often should a sacrificial anode be replaced?

The frequency of replacing a sacrificial anode in a water heater varies depending on its type, location, and usage. Generally speaking, it is recommended to replace the anode every three to four years. This timeline can be shortened if the tank experiences high levels of hard water or other forms of mineral build-up which can erode the anode’s effectiveness. Additionally, if the water heater is located in an environment where temperatures rise and fall frequently, this may also lead to more frequent replacement requirements.

To determine when a sacrificial anode should be replaced, it is important to inspect it regularly for signs of wear and deterioration. If corrosion has begun to affect the metal in any way or if there are significant changes to its shape or size, then it is time to replace the anode as soon as possible. This will help prevent further damage from occurring within the water tank and ensure that all necessary safety measures are taken in order to protect its inhabitants from potential hazards.

It is also a good idea to flush out sediment and debris that has built up inside the tank once every few months in order to increase the lifespan of both the sacrificial anode and your water heater itself. Doing so will help reduce mineral build-up which can accelerate corrosion of the anode over time. In addition, regular maintenance should include replenishing electrolytes through rebalancing treatments which are designed specifically for this purpose.

Overall, taking proactive steps such as performing routine inspections and maintenance tasks will help extend your sacrificial anode’s lifespan so that you don’t have to worry about replacing it too often or unexpectedly early. That being said, depending on individual circumstances certain tanks may require replacement more frequently than others so it is always best practice to stay mindful and check up on your water heater regularly.

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