What is a Chimney Liner
A chimney liner is a corrugated tube made from one or more layers (strips) of metal which are inter-locked with each other to form a continuous pipe (most often round, sometimes oval or square).
The purpose of a chimney liner is to make old chimneys usable for the purpose of venting natural-draft equipment - stoves, fireplace inserts, water heaters, boilers, etc. Since most masonry chimneys in the USA are decades old and degraded, using them may pose both health and safety risks and therefore a liner should be used to mitigate these risks.
Types of Chimney Liners
Stainless Steel chimney liner is the most common type and is an All-Fuel type, compatible with all types of fuel (gas, wood, oil, pellets). It offers the highest temperature resistance (up to 1,000°F running and up to 1,400°F occasional). It is available in (3) distinct types:
Standard - as described above.
Smoothcore - double-layer liner comprised of a smooth-wall inner core and standard corrugated outer exterior, both made from stainless steel. Unlike with standard corrugated liner, smooth inner walls of Smoothcore allow for better draft, better condensation drainage and a much higher resistance to soot and creosote build-up (when used with wood-burning stoves and fireplace inserts), resulting in a distinctively superior product.
Pre-insulated - a 3-layer liner comprised of standard corrugated stainless steel inner core, followed by foil-faced ceramic insulation and an aluminum exterior jacket. This liner is ideal for wood stoves since it already comes with factory pre-installed insulation, has an outer protective jacket and zero-clearance requirement (great for small chimneys). Since ceramic insulation is required for wood-burning applications, this is the #1, all-in-one, code-compliant solution for venting a wood stove through an existing masonry chimney. No messy ceramic insulation to deal with + the aluminum jacket protects the inner layers from damage during installation (frustrating and time-consuming to repair) as we as from moisture and sagging. Note: due to added insulation layer, the actual OD of this liner is 1" larger than the nominal size (6" pre-insulated liner would be 7" actual OD).
Aluminum chimney liner is intended for use with gas (natural and propane) appliance only. It's most typical applications are for gas fireplaces and fireplace inserts, gas water heaters and gas boilers. They are available in (2) types:
Standard - as the name suggests, these are standard aluminum corrugated liners suitable for most applications.
Pre-Insulated - a 3-layer version of the standard liner, with a layer of insulation between inner and outer aluminum jackets. The main advantage offered by the insulation layer is better draft (due to much lover interior and exterior temperature differences) and higher resistance to the formation of corrosive condensate (which is especially common when running the liner in an exterior chimney). Pre-insulated aluminum liner offers a longer lifespan and less worries for the homeowner. Note: insulation is not required for aluminum liner by code at present and simply offers a better performance and longer lifespan. Also, due to added insulation layer, the actual OD of this liner is ~1" larger than the nominal size (4" pre-insulated liner would be 5" actual OD).
Frequently Asked Questions
Q: St. Steel vs Aluminum liner - what's the difference?
A: Stainless steel is an All-Fuel type, suitable for all common fuels - gas, oil, wood & pellets. Aluminum is for use with Category I, gas-fired (natural or propane) appliances only.
Q: Is there any difference between 316Ti, 316L and 304 stainless steel chimney liners?
A: Yes, there's a substantial difference between these. 304 st. steel is on a much lower level than 316Ti and 316L st. steels in terms of corrosion resistance. We would not recommend using 304 steel chimney liners since steel used in making the liner itself is very thin (0.005" or 0.006") and is not likely to handle prolonged exposure to fumes and condensate from burning fuel. The difference in cost between 304 and 316 grades is small and not worth the trouble in our opinion.
316Ti vs 316L - the 316Ti is a titanium-stabilized steel specifically developed for use in chimney liners (to withstand high temperatures, temperature variances and corrosive environment), so this steel offers better performance than the 316L type, despite 316L being a very good, time-tested alloy.
Q: Do you have to insulate the chimney liner?
A: It depends:
Aluminum - No
St. Steel (Standard), for gas and oil-fired equipment - No
St. Steel (Standard), for wood-burning applications - Yes
St. Steel (Pre-Insulated) - No
Q: How to insulate the chimney liner?
A: The (3) methods are:
1. Purchase a pre-insulated liner - it is the easiest, fastest and cleanest method, albeit more expensive.
2. Buy an insulation kit (1/2" thick ceramic foil-faced insulation with mesh or other means of securing the insulation to the liner) - it is much more time-consuming, still exposes the insulation to potential damage during the installation (especially if chimney walls are not smooth) and moisture inside the chimney, but it is cheaper.
3. Use vermiculite-based insulation mix to create a minimum 1" thick layer around the liner. This method is the cheapest, but also the hardest one to implement and is the most time-consuming.
Q: What is the difference between chimney liner insert kits and tee kits?
A: Insert kits come with an insert adapter, which connects the chimney liner directly to the gas or wood stove or fireplace insert. These kits are most common for vertical venting where chimney is right above or almost above the stove/fireplace flue outlet. In other words, insert kits are best for fireplace inserts (wood or gas).
Tee kits include a tee fitting instead on an adapter. The liner connects to the tee vertically (the other end pointing down - for cleanout) and the stove is connected to the side of the tee with regular stove pipe (often with 1 vertical run, 1x 90 elbow or 2x 45's and 1 horizontal run to the tee). This kit is best for installations where a wood stove is installed in the living or basement space and not inside the fireplace.
Q: Are any special adapters/parts needed with these kits?
For most installations, the kit includes all the needed parts (except for insulation for standard st. steel liners). We also stock the parts for:
Tight installations - inside fireplaces where the stove/fireplace insert flue top does not align with the chimney - such as Offset Adapters and Swivel Offset Elbows.
Installations using vermiculite - roof flashings could be trimmed to size and used to stop vermiculite mix at the bottom of the chimney.
As well as spare rain caps, tees, adapters and other parts - to accommodate any project.
