Coating & Tank material in water heaters (Stainless steel, Polymer, Glass Lined)

What is the main purpose of buying a water heater?

You need hot water to bathe, wash utensils, etc during the winter months. The water heater enables you to do that.

When you venture into the market to make the purchase, you tend to get confused over which geyser to buy because of the wide range of appliances available on display.

You either end up buying the one your friends or relatives recommend or the one the salesman pushes you to buy. You make the wrong choice in both the cases.

This is because the requirements of each family are different. This water heater buying guide can solve many of your issues. In this part, we discuss the different types of coating and material of the storage tank and its effects.

Coating –Why?

The purpose of buying a storage water heater is that you are able to store hot water to use it subsequently when required. The storage time could be ten minutes or even an hour depending on the utility.

Under such circumstances, you cannot avoid corrosion. Secondly, you find the input water supply is always in the ‘ON’ position in geysers. Hence, these water heaters are always full of water every time.

This brings the corrosion aspect into the picture. The water heater manufacturers coat the inner surface of these appliances with an anti-corrosive material to prevent corrosion when it is in contact with warm water. This increases the longevity of the appliance.

Bajaj Instant Geyser

Storage Tanks – Materials Used

These are the normal materials used in manufacturing storage tanks in geysers.

  • Copper
  • Stainless Steel
  • Thermoplastic

Let us do the comparison among the three materials mentioned above. Everyone knows that copper is a good conductor of heat. This can result in heat loss. Stainless steel is a better option as it provides comparatively better insulation. Both stainless steel and copper are corrosive thereby requiring an anti-corrosive coating.

Thermoplastic is non-corrosive but is not a good insulator. This comparison brings us to the conclusion that stainless steel tanks are the best as far as the combination of insulation and anti-corrosive properties are concerned.

An additional layer of protection over the stainless steel tanks can serve the purpose. Let us go into the details of such anti-corrosive coating materials.

Read: Instant vs Storage Geyser

Coating Materials

As you narrow down your selection of water heaters, you come to the nature and quality of coating materials used in geysers. You will come across names as follows.

Let us discuss the latest technologies used by the top water heater manufacturers in India.

  • Blue Diamond Glass – Glass is advantageous because it is a bad conductor of heat. In addition, it does not rust and protects the water tank interiors from corrosion. AO Smith geysers use this technology for coating their water tanks.
  • Titanium Glassline or Enamel – This technology is similar to Blue Diamond Glass. Bajaj water heaters use Titanium Armor technology to prevent the inner surface of the water tank from rusting. Racold heaters use Titanium Plus technology, where the water tank comes coated with Super Polymer High-Performance coating to prevent corrosion.
  • Blue Sapphire Glass – Blue Sapphire Glass coating is similar to Blue Diamond coating. Usha storage heaters offer this technology in their premium water heater models.
  • Feroglas Technology – Feroglas is different because this technology uses dry powder to coat the inner surface of Havells water heater tanks. This proprietary technology uses thick, super-cold rolled steel plates with a single weld design that adds to the geyser’s durability.
  • Nano Coating – Nano polymer coating is a popular coating technology used in the latest Crompton Greaves storage geysers. This technology involves coating the inner walls of the water storage tank with nano polymer to prevent corrosion.

Read: Best Geysers

Final thoughts

Better the insulation lower is the heat loss. This factor along with the standing loss concept drives the BEE star ratings. Hence, the ideal combination should be a stainless steel tank with polymer or glass coating.

The star rating is an important factor. Go for a 5-star rated geyser. It might be a bit expensive initially, but the costs work in your favor when you use it for a long time.

The warranty offered by the manufacturer has a bearing on your decision. Normally, you have manufacturers providing a longer warranty on geysers having better corrosive protection. Checking out the warranty before purchasing the appliance is advisable.

Sources:, Wikipedia

Geetha Srinivasan
Geetha Srinivasan
Geetha Srinivasan, a retired homemaker, holds a Bachelor's degree in Food Science and Technology From Anna University. She is a culinary and kitchen appliance expert with an impressive 30 years of experience in testing kitchen appliances like Mixer Grinders, Juicers, Food Processors, Air Fryers, and Ovens, Beyond appliances, she excels in kitchen organization, cleaning, and cooking, delighting family and friends with her culinary skills. At 55, her passion for all things culinary burns bright.



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