DuraVent DuraFlex 316 Basic Kit: a chimney liner kit for harsher exhaust
The DuraVent DuraFlex 316 Basic Kit is a liner and fittings package for an old masonry chimney. Its 316 stainless steel handles more corrosive exhaust than 304, including coal or high sulfur oil. It suits chimneys with few bends. DuraFlex Stainless is DuraVent’s flexible stainless steel liner for relining a masonry chimney that vents a wood, pellet, oil, or gas appliance. The box includes the liner coil, a chimney top plate with a welded rain collar, a removable cap, and a bottom connector. For several chimney bends, the Pro liner offers tighter bending than 304 or 316.
Choose a length of 15, 20, 25, 30, or 35 feet, then a diameter of 3, 4, 5, 5 1/2, 6, 7, or 8 inches. Gas, oil, and pellet liners can touch the masonry without insulation. Wood liners need 1 inch of air space or a half inch ProFoil blanket wrap to touch the masonry. Insulation is separate. Connecting through the chimney wall? Choose the DuraVent DuraFlex 316 Tee Kit with a side connection instead of the bottom connector. The DuraVent DuraFlex 316 Basic Kit ships free from My Cozy Outdoors with No Sales Tax (except WY) and the full manufacturer warranty.
Details
SKU: 3DF316-15K | 4DF316-15K |5DF316-15K |55DF316-15K | 6DF316-15K | 7DF316-15K | 8DF316-15K
SKU: 3DF316-20K | 4DF316-20K |5DF316-20K |55DF316-20K | 6DF316-20K | 7DF316-20K | 8DF316-20K
SKU: 3DF316-25K | 4DF316-25K |5DF316-25K |55DF316-25K | 6DF316-25K | 7DF316-25K | 8DF316-25K
SKU: 3DF316-30K | 4DF316-30K |5DF316-30K |55DF316-30K | 6DF316-30K | 7DF316-30K | 8DF316-30K
SKU: 3DF316-35K | 4DF316-35K |5DF316-35K |55DF316-35K | 6DF316-35K | 7DF316-35K | 8DF316-35K
Applications
- DuraFlex Pro ultra flexible relining for masonry chimney. Use with gas, wood pellet, oil, or wood appliances. Applications include: fireplace inserts, furnaces, boilers, and water heaters.
- DuraFlex SW smooth wall flexible relining for masonry chimney. Use with gas, wood pellet, oil, or wood appliances. Applications include: fireplace inserts, furnaces, boilers, and water heaters.
- DuraFlex 316 flexible relining for masonry chimney. Use with gas, wood pellet, oil, or wood appliance. Applications include: fireplace inserts, furnaces, boilers, and water heaters. 316 is designed for use in harsher conditions, for more resistance to corrosion, such as coal.
- DuraFlex 304 flexible relining for masonry chimney. Use with gas, wood pellet, oil, or wood appliances. Applications include: fireplace inserts, furnaces, boilers, and water heaters.
Materials and Construction
DuraFlex Pro: Single-wall .005″ 316 stainless steel.
DuraFlex SW: Single-wall .005″ overlapped 316 stainless steel (totalling .010″). Overlapped to create smooth inner wall.
DuraFlex 316 & 304: Single-wall .005” 316 or 304 stainless steel.
Clearances
DuraFlex Pro: 0″ clearance for gas, oil, and pellet applications. 1″ clearance to masonry for wood-burning applications. Insulation is required for 0″ clearance to masonry for wood-burning.
DuraFlex SW: Clearances 0″ clearance for gas, oil, and pellet applications. ” clearance to masonry for wood-burning applications. Insulation is required for 0” clearance to masonry for wood-burning.
DuraFlex 316 & 304: 0″ clearance for gas, oil, and pellet applications. 1″ clearance to masonry for wood-burning applications. Insulation is required for 0″ clearance to masonry for wood-burning.
Diameters
DuraFlex Pro & SW: 3″ – 12″.
DuraFlex 316 & 304: 3″ – 8″.
Listings
DuraFlex Pro: Listed to UL 1777 and ULC S635 (MH45609).
DuraFlex SW: Listed to UL 1777 (MH45609).
DuraFlex 316 & 304: Listed to UL 1777 and ULC S635 (MH45609).
FAQ
What is in the DuraFlex 316 Basic Kit?
A DuraFlex SS Top Plate with welded Storm Collar, a Removable Vertical Cap, a DuraFlex SS Connector and one length of DuraFlex 316 liner in your choice of 15, 20, 25, 30 or 35 feet. Select the length and then the diameter (3 to 8 inches) on the page; the liner must match the appliance outlet and reach the chimney top.
When is the 316 liner the right choice?
DuraFlex 316 is the lighter, more economical liner for chimneys with few or no offsets, and DuraVent recommends 316 over 304 where corrosion resistance matters more, such as coal-fired appliances. It is intended for wood-burning, non-condensing gas and oil appliances and is listed to UL 1777 and ULC S635. For a flue with several offsets, DuraFlex Pro is the more flexible option.
What clearance and insulation does it need?
Zero clearance to the masonry for gas, oil and pellet appliances, with insulation optional but recommended for draft on exterior chimneys. For wood burning keep 1 inch to the masonry, or insulate with a 1/2-inch ProFoil or Flexwrap blanket (or 1 inch of TherMix) to reach the zero-clearance listing; the ProMesh Insulation Kit is sold separately.
Can the liner be shortened or squeezed to fit?
Yes. Cut DuraFlex 316 with a hacksaw or a reciprocating saw with a metal blade, and ovalize a round liner that will not pass the flue, remembering that ovalizing reduces the cross-section; DuraVent’s L1244 guidance covers it. Have a certified sweep inspect and clean the chimney before the liner goes in.
Basic Kit or Tee Kit for my appliance?
The Basic Kit’s connector suits a liner that drops straight to a fireplace insert or a stove in the fireplace opening; an appliance connected through the chimney wall from the side needs the 316 Tee Kit with its clean-out tee instead. Both share the top plate and cap; all versions are in the DuraFlex Stainless category.