When shopping for a chimney liner, you will find a variety of materials and configurations designed for different fuel-burning appliances and venting systems. Metal chimney liners are also available in convenient kits that include a flexible metal liner and the fittings needed for a complete installation. While an aluminum liner may appear attractive because it costs less than stainless steel, or a rigid stainless steel liner may seem like a more affordable alternative to flexible stainless steel, it is important to choose a liner that is appropriate for your specific application.
To make sure you select the correct product, consult a qualified chimney professional and review the applicable local building codes for your system. In general, stainless steel liners are required for applications exposed to high temperatures or corrosive flue gases. A rigid stainless steel liner may be suitable for a chimney with a straight, vertical flue and no offsets or bends. However, if the flue has bends, the additional fittings and installation work required to accommodate a rigid liner can make a flexible stainless steel liner the more practical option.
Aluminum liners are generally intended for specific low-temperature applications, such as certain low-efficiency gas or oil-burning boilers, furnaces, or water heaters. Combustion gases contain water vapor and other compounds that can condense inside a cooler chimney and contribute to corrosion. The higher exhaust temperatures produced by some low-efficiency appliances can help keep these gases above their condensation point until they exit the chimney, making aluminum suitable for certain approved installations. Always verify that an aluminum liner is approved for your particular appliance and venting system before selecting one.
If your appliance produces lower-temperature flue gases that are likely to condense inside the chimney, you will need an appropriate grade of stainless steel liner designed to withstand corrosive condensation. High-efficiency furnaces and similar appliances can produce relatively cool exhaust gases, making proper liner material especially important. Woodstoves and fireplaces present additional challenges because they can produce very high temperatures while also creating conditions that encourage creosote formation and condensation. For these applications, a properly rated stainless steel liner can provide the durability and heat resistance needed for the system.
When planning a chimney liner installation, always select materials that are specifically rated and approved for your appliance and venting application. Flexible stainless steel liners may cost more than some alternative materials, but when stainless steel is the appropriate choice, the right liner can provide long-term durability, reliable performance, and an important layer of protection for your home.