Should You Choose Stainless Steel Or Vitreous Enamel For Your Hot Water System Tank?

Introduction

When it comes to selecting a hot water system tank, the choice between stainless steel and vitreous enamel can have a significant impact on the tank’s longevity and performance. Both materials have their own unique advantages and considerations, particularly when it comes to the effects of chlorine, a common disinfectant added to municipal water supplies.

In this blog post, we’ll explore the key differences between stainless steel and vitreous enamel hot water tanks, focusing on how each material holds up against the corrosive effects of chlorine. By understanding the pros and cons of each option, you can make an informed decision that best suits your hot water needs and budget.

What are the choices or some examples?

iHeat 300L:

• Glass lined vitreous enamel tank
• Slimline design for tight roof spaces
• 4m2 collector area
• Suitable for medium to high hot water demand
• Includes an in-tank electric booster
• 7-year warranty on the tank and collectors

Envirosun TS Solar System:

• 444 marine grade stainless steel tank
• Larger 5.2m2 collector area
• Suitable for high hot water demand
• Includes an in-tank electric booster
• 10-year warranty on the tank and collectors
• Designed to withstand harsh Australian conditions

The key differences between these two systems are the tank material, collector size, and warranty periods. The iHeat 300L is a good choice for medium to high hot water demand with its slimline design, while the Envirosun TS is better suited for high hot water usage homes due to its larger collector area and premium stainless steel tank. The Envirosun TS also comes with a longer 7-year warranty compared to the iHeat’s 7-year warranty, making it a more durable long-term option.

In terms of pricing, the Envirosun TS is typically more expensive than the iHeat 300L due to the higher-quality components and larger collector size. However, the increased performance and extended warranty of the Envirosun TS may justify the higher upfront cost for some homeowners.

Effects of Chlorine on Vitreous Enamel hot water tanks.

1. Vitreous Enamel Coating:

• Vitreous enamel is a type of hard, glossy ceramic coating applied to the interior of hot water tanks.
• It is designed to provide a durable, corrosion-resistant barrier between the tank’s metal shell and the water.

2. Chlorine Corrosion:

• Chlorine is commonly added to municipal water supplies as a disinfectant.
• Over time, the chlorine can react with the vitreous enamel coating, causing it to break down and exposing the underlying metal.

3. Corrosion Effects:

• The exposure of the metal tank to the chlorine-treated water can lead to accelerated corrosion, pitting, and eventual failure of the tank.
• This can result in leaks, water damage, and the need for premature tank replacement.

4. Increased Maintenance:

• Chlorine corrosion can require more frequent tank inspections and maintenance to monitor the condition of the vitreous enamel.
• In some cases, the tank may need to be replaced sooner than expected due to the corrosive effects of the chlorine.

5. Water Quality Impacts:

• As the vitreous enamel coating degrades, it can contribute to discoloration, odor, and potentially even the release of heavy metals into the hot water.

6. Prevention and Mitigation:

• Flushing the tank with a 5 year service when replacing the anode can help remove any “pooled” contaminates that have built up over the years.
• Installing an inline filter or a whole-home water filter can also help to reduce the impact of chlorine on the tank’s interior, increasing the overall life span of the system.

Effects of chlorine corrosion on 444 marine grade stainless steel hot water tanks.

1. Chlorine Resistance:

• 444 marine grade stainless steel has excellent resistance to chlorine-induced corrosion due to its high chromium and molybdenum content.
• The chromium forms a passive oxide layer that protects the underlying metal from the corrosive effects of chlorine.

2. Pitting and Crevice Corrosion:

• The molybdenum in 444 marine grade stainless steel further enhances its resistance to pitting and crevice corrosion, which can be a concern in chlorinated water environments.
• This helps prevent the formation of localised corrosion that can eventually lead to tank failures.

3. Chlorine Resistance:

• The molybdenum in 444 marine grade stainless steel further enhances its resistance to pitting and crevice corrosion, which can be a concern in chlorinated water environments.
• This helps prevent the formation of localised corrosion that can eventually lead to tank failures.

4. Uniform Corrosion:

• Even in the presence of chlorine, 444 marine grade stainless steel exhibits a high degree of uniform corrosion resistance.
• This means the tank material corrodes at a slow, predictable rate, rather than experiencing accelerated, localised pitting.

5. Maintenance Requirements:

• Due to the superior corrosion resistance of 444 marine grade stainless steel, hot water tanks made from this material may require less frequent inspections and maintenance compared to tanks with less chlorine-resistant coatings or materials.
• The durable nature of the 444 stainless steel can extend the tank’s lifespan in chlorinated water applications.

6. Water Quality:

• The corrosion-resistant properties of 444 marine grade stainless steel help prevent the leaching of metals or the release of contaminants into the hot water, maintaining water quality.
• This is particularly important in applications where the hot water is used for drinking, bathing, or food preparation.

Conclusion

The choice between stainless steel and vitreous enamel for a hot water system tank ultimately comes down to weighing the unique advantages and drawbacks of each material. Stainless steel, particularly the 444 marine grade variety, offers superior resistance to chlorine-induced corrosion, helping to extend the tank’s lifespan and maintain water quality. Conversely, vitreous enamel tanks may require more frequent inspections and maintenance to monitor the potential breakdown of the coating due to chlorine exposure.

When making your decision, consider factors such as your local water quality, the expected usage and lifespan of the hot water system, and your budget. Consulting with a qualified plumber or water treatment specialist can also provide valuable insights to ensure you choose the right tank material for your specific needs. By understanding the impact of chlorine on these tank options, you can make an informed choice that will provide reliable, long-lasting hot water for your home or business.