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The Difference Between 316 and 904 Chimney Flue Liner

Facing a choice between two stainless steel chimney liners, labeled 316 and 904 grade, is essential for the efficiency and safety of your fireplace. Each liner channels smoke and fumes, but their materials differ significantly. This difference influences both the durability of your chimney against corrosion and the compatibility with your chosen fuel type.

Understanding these distinctions is crucial for mintaining your home's warmth and safety. Let's look at what differentiates these materials and their suitability for your needs.


Key points:

  • 904 Grade Stainless steel is more suited to a wider range of fuel types
  • 904 grade is higher quality and therefore more durable; but it comes at a prices


Material Composition

The main distinction between 316 and 904 [link to chimney-liner.html]chimney flue liners[/link] arises from their material compositions, tailored to perform optimally in different settings. The 316 liners comprise iron ore, silicon, nickel, chromium, molybdenum, and carbon in specific ratios. This blend suits wood-burning well, offering durability and efficiency for wood combustion's demands.

In contrast, 904 liners incorporate the same elements as 316 liners but in altered ratios. These adjustments enhance their capacity to endure more severe conditions, making them preferable for burning solid fuels such as coal or oil. The modified composition of 904 liners increases their strength and accounts for their higher cost. Thus, the fuel type significantly influences the choice between these liners, with 904 liners excelling in handling the aggressive byproducts of solid fuels.

To further complicate things, modern liners are actually constructed from two layers of stainless steel; so you can get 316/316, 316/904 or 904/904. (At National Chimney Supplies, we only stock 316/316 and 904/904)

Corrosion Resistance

When comparing the two types of liner, it's essential to note that 904 liners offer better resistance to corrosion. This is particularly true in regard to acidic by-products produced during fuel combustion. The superior corrosion resistance of 904 liners stems from their higher chromium content, making them more resilient against corrosive chemicals. Consequently, 904 liners are the preferable option in conditions requiring such resistance.

While 316 grade liners perform adequately in most situations, they may degrade when exposed to strong, corrosive chemicals for extended periods. In contrast, 904 grade liners provide exceptional protection in aggressive environments. The use of 904 stainless steel in high-durability products, such as Rolex watches, highlights its outstanding corrosion resistance.

In deciding between 316 and 904 liners, consider that the durability and performance of your chimney flue liner largely depend on its corrosion resistance. Choosing a 904 liner might be a prudent decision for ensuring long-term durability and efficiency.


Fuel Type Suitability

When selecting a chimney flue liner, you must consider the fuel you plan to use and your burning habits.

A 316 grade liner suits those who burn dried wood, gas, oil, or low sulfur coal. It efficiently handles these fuel types, making it a versatile choice. However, for heavy use or with smokeless fuels, it may not be the best option.

If you want to burn a wider range of fuels, including wood, coal, gas, oil, coke, peat, or smokeless fuels, a 904 grade liner is recommended. It's designed for solid fuels and offers durability for multi-fuel stoves or frequent fuel changes.

The choice therefore depends on your fuel usage. Matching the liner to your habits ensures optimal performance of your installation.

Performance and Longevity

When assessing durability and longevity, 904 stainless steel liners outperform 316 liners in resisting acidic condensation. This resistance significantly extends their lifespan, making them a better choice for burning solid fuels like coal or oil, which create more acidic by-products. Therefore, opting for a 904 liner means selecting a more durable and reliable solution for your chimney.

However, the lifespan of a chimney liner depends not only on the material but also on regular maintenance. Both 316 and 904 stainless steel liners need frequent sweeping and proper care to remain effective. The superior composition of 904 liners, though, makes them more resilient to the wear and tear of maintenance, thus lowering the likelihood of damage over time.

Furthermore, proper burning practices are crucial. While 316 liners may be adequate for standard stove use, the switch to 904 liners becomes imperative under harsher conditions. This switch ensures that long-term exposure to aggressive condensates doesn't compromise the liner's performance or longevity. In essence, choosing a 904 liner meets immediate requirements and protects the chimney's functionality in the future.

Making the Right Choice

Choosing between a 316 and a 904 chimney flue liner depends on two key factors: the type of fuel you plan to use and your burning habits. If wood will be your primary fuel, consider the 316-grade liner. This liner is suitable for wood burning, offering a good balance between performance and longevity.

Conversely, if you intend to burn solid fuels such as coal or oil, the 904-grade liner is advisable. This liner boasts superior resistance to the corrosive chemicals present in these fuels, making it a more durable option under such conditions.

In making your decision, don't solely consider the initial cost. A 904 liner, though more expensive initially, may prove more economical over time due to its longevity. Each option has its advantages, but the best choice for your chimney will depend on the fuel type and your burning habits. Consider both the short-term benefits and the long-term durability to make an informed decision.


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