Do Glass lined Water Heaters Have Anode Rods

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Glass-lined water heaters have anode rods. The tanks are made of steel lined with glass. The glass does protect the tank against corrosion, but it is vulnerable to cracking and leaking, so anode rods are still required. The glass also helps to insulate the tank, making it more energy-efficient.

Manufacturers of water heaters and their storage tanks often use glass linings as protection against rust. But when you decide to buy a glass-lined heater, they tell you that you definitely need an anode rod for storage tank protection against corrosion. In these situations, it’s natural to be slightly confused and ask yourself what is the purpose of the lining then.

This article will cover why glass-lined heaters require an anode rod and why the glass lining is still valuable regardless.

Purpose of Glass Is to Protect Tank From Corrosion

Glass lining is one of the safety features of water heaters. It serves as a barrier to stop the water from being in constant direct contact with the steel water tank. Therefore, the lining provides the tank protection from corrosion to some extent.

It also acts as an additional insulation layer that helps the heat to stay within the tank, making it more efficient in its function.

However, in order to obtain the ultimate protection from rust, any glass-lined water heater also needs an anode rod. Why?

Glass Lining Is Not Perfect Barrier

Glass lining doesn’t last very long when left on its own as the sole source of rust prevention. This is due to its somewhat fragile nature.

With time and heavy use, it begins to split and crack, allowing the water to come in contact with the outer layer of the tank and eventually causing it to corrode. The lining could also get damaged during heavy transportation or during unprofessional heater installation.

Even small cracks in the lining could cause leaks into the metal casing of the tank, decrease the heater’s efficiency, or ultimately damage the water tank. This is why the glass-lined water heaters also need an anode rod to protect them from rusting.

When the water starts getting through the cracks in the glass lining, an anode rod acts to stop corrosion and ensure the efficient run of the heater. Without the rod, the lifespan of the heater would be radically shortened, and the quality of the water could decrease.

However, keep in mind that not all glass linings are created equal and that some are more durable than others. Generally, it depends on the manufacturer, so it is good to opt for established reliable brands, like State or Rheem. Either way, you should still invest in a good anode rod as well.

Is Glass Lining Pointless?

Just because an anode rod is required, it does not mean that the lining doesn’t have its place in the water heaters. It still plays a vital role in the heater’s safety and efficiency.

We can say that the rod is the only thing protecting the tank from corrosion when the lining cracks. But we should also point out that the lining is the only thing preventing the water from being in continuous, direct contact with the tank, thus protecting it from corrosion even when the rod deteriorates.

The truth is that the glass lining and the anode rod both need each other in order to prolong the water tank’s lifespan and provide it with maximum rust protection.

If the tank didn’t have any lining protecting the majority of its surface, the anode rod would most likely not be able to prevent rusting of the whole tank. It would probably deplete very quickly, but most importantly, it would not work efficiently enough to protect the tank and stop leakages.

On top of that, the glass provides additional insulation, so without it, the heater would be losing a lot of heat, causing it to be a lot less efficient.

Indirect Glass-Lined Water Heaters

Indirect water heaters with glass-lined tanks also require anode rods because the tank is still present in the unit. However, the tank takes less strain in general in these models as there is no compounding factor of the harshness of the heating element or gas flame.


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