For people who aren\u2019t familiar with how storage tank water heaters work, it may seem strange that they don\u2019t start to corrode and rust early in their service lives. After all, they\u2019re made of metal and hold large amounts of water. Doesn\u2019t the combination of water and metal mean the promotion of rust?<\/p>\n
Modern water heaters are designed specifically to resist corrosion. The inside of their tanks are glass-lined, and the oxygen necessary for corrosion to start is kept out of the main tank and inside an expansion tank instead. One crucial component for preventing corrosion is a part called the anode rod or the sacrificial rod.<\/p>\n
An anode rod is made from magnesium or aluminum around a core steel wire. The rod is attached to the top of the water heater tank and extends down into it. When two metals (such as aluminum and steel) are connected in water, one of the metals will corrode while the other will not. The less reactive metal (called the \u201cnobler\u201d metal in chemistry terms) will not suffer from corrosion, while the other metal remains intact. In this case, the magnesium\/aluminum of the anode rode will attract the ions that cause corrosion, leaving the steel in the center of the rod\u2014as well as the steel of the tank itself\u2014corrosion-free. Essentially, the outer part of the anode rod \u201csacrifices\u201d itself to protect the rest of the tank.<\/p>\n
Once the magnesium or aluminum of an anode rod has fully corroded, the rod will no longer protect the tank. This is one of the reasons that it\u2019s vital to schedule routine maintenance for your water heater. Professionals will always check the anode rod to see its current state. If it is coming close to corroding to the core, the technicians will replace it so you\u2019ll have continued protection for your water heater.<\/p>\n