DuraVent FasNSeal Flex 3" x 40' Stainless Steel Custom Flex Length
SKU: 75055095943

DuraVent FasNSeal Flex 3" x 40' Stainless Steel Custom Flex Length

Sale price$526.32 Regular price$584.80
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Description

DuraVent FasNSeal Flex 3" x 40' Stainless Steel Custom Flex LengthMade from super ferritic stainless steel. Corrosion resistant. Manufactured with a sure seal locking seam for superior strength and flexibility. The smooth inner wall provides for no output reduction, allowing for full appliance efficiency, ease of cleaning and regular maintenance. The smooth inner wall optimizes gas flow, minimizes back pressure, and facilitates condensate management. Only flexible chimney liner listed to UL 1738 standard. What's

Made from super-ferritic stainless steel. Corrosion resistant. Manufactured with a sure-seal locking seam for superior strength and flexibility. The smooth inner-wall provides for no output reduction, allowing for full appliance efficiency, ease of cleaning and regular maintenance. The smooth inner wall optimizes gas flow, minimizes back pressure, and facilitates condensate management. Only flexible chimney liner listed to UL 1738 standard. 

What's Included

  • Flex Length (Custom)

Features

  • Available in 2" - 12" diameter
  • Available in 20' - 200' length
  • Can only be used in vertical or near vertical runs.
  • Use with FasNSeal components only.
  • Listed to UL 1738.
  • Use to vent Category II, III, and IV gas burning appliances.

Specifications

Brand DuraVent
Series FasNSeal Flex
Model 3FSFLEX-40
Product Type Flex Length (Custom)
Construction Single Strip Double Layer Super-Ferritic Stainless Steel (Totalling .010″)
Size (Diameter) 3"
Length 40'

Warranty

DuraVent, Inc. (“DuraVent”) provides this limited lifetime warranty for all of its products with the exception of Ventinox® (lifetime), and PolyPro® (ten years). Subject to the limitations set forth below, DuraVent warrants that its products will be free from defects in material or manufacturing, if properly installed, maintained, and used.
Click to See Warranty Coverage and Limitations


DuraVent, Inc. (“DuraVent”) provides this limited lifetime warranty for all of its products with the exception of Ventinox® (lifetime), and PolyPro® (ten years). Subject to the limitations set forth below, DuraVent warrants that its products will be free from defects in material or manufacturing, if properly installed, maintained and used. DuraVent products are fully warranted if installed only by a professional installer. This Warranty is transferable from the original homeowner to the buyer of the home. This warranty does not cover normal wear and tear, smoke damage or damage caused by chimney fires, acts of God, or any product that was: (1) purchased other than from an authorized DuraVent dealer, retailer or distributor; (2) modified or altered; (3) improperly serviced, inspected or cleaned; or (4) subject to negligence or any use not in accordance with the installation instructions included with the product as determined by DuraVent.

 

DuraVent provides the following warranties for its products: One Hundred Percent (100%) MSRP 15 years from the date of purchase, and Fifty Percent (50%) thereafter, except for the following limitations on: all Termination Caps and DuraBlack® are warranted at One Hundred Percent (100%) for five years. All warranty obligations of DuraVent shall be limited to repair or replacement of the defective product pursuant to the terms and conditions applicable to each product line. These remedies shall constitute DuraVent’s sole obligation and sole remedy under this warranty. This warranty provides no cash surrender value. The terms and conditions of this warranty may not be modified, altered or waived by any action, inaction or representation, whether oral or in writing, except upon the express, written authority of an executive officer of DuraVent.

 

Corn, bio-fuels, driftwood or other wood containing salt, preservative-treated lumber, plastic and household trash or garbage, or wood pellets containing such materials must not be burned in the appliance or fireplace. In case of a chimney fire, the chimney must be inspected and approved by a certified Chimney Sweep before reuse. After each annual inspection, maintenance, and cleaning, the certified Chimney Sweep must fill out and date the appropriate section of the warranty card provided with the chimney liner.

 

LIMITATIONS ON INTERNET SALES: Notwithstanding any other terms or conditions of this Limited Lifetime Warranty, DuraVent provides no warranty for the following specific products if such products are not installed by a qualified professional installer: DuraTech®, DuraTech® DTC, DuraTech® Premium, DuraPlus HTC®, DDW®, DuraChimney® II, PelletVent Pro®, DirectVent Pro®, FasNSeal®, FasNSeal® W2, FasNSeal® Flex, and PolyPro®, and DuraVent’s relining products including DuraLiner®, DuraFlex® (SW, Pro, 316, 304), and Ventinox®. For purposes of this warranty, a trained professional installer is defined as one of the following: licensed contractors with prior chimney installation experience, CSIA Certified Chimney Sweeps, NFI Certified Specialists, or WETT Certified Professionals.

 

DuraVent must be notified and given the opportunity to inspect defective product prior to replacement under the terms of this limited lifetime warranty. All warranty claims must be submitted with proof of purchase. Labor and installation costs are not covered under this warranty. To obtain warranty service contact: DuraVent Warranty Service, 877 Cotting Ct., Vacaville CA 95688, or call 800-835-4429.

 

WHERE LAWFUL, DURAVENT DISCLAIMS ALL OTHER WARRANTIES, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT WILL DURAVENT BE LIABLE FOR INCIDENTAL, CONSEQUENTIAL, PUNITIVE OR SPECIAL DAMAGES OR DIRECT OR INDIRECT LOSS OF ANY KIND, INCLUDING BUT NOT LIMITED TO PROPERTY DAMAGE AND PERSONAL INJURY. DURAVENT’S ENTIRE LIABILITY IS LIMITED TO THE PURCHASE PRICE OF THIS PRODUCT. SOME STATES DO NOT ALLOW LIMITATIONS ON IMPLIED WARRANTIES, OR THE EXCLUSION OR LIMITATION OF INCIDENTAL OR CONSEQUENTIAL DAMAGES, SO THE ABOVE LIMITATIONS AND EXCLUSIONS MAY NOT APPLY TO YOU. THIS LIMITED WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, AND YOU MAY ALSO HAVE OTHER RIGHTS THAT VARY FROM STATE TO STATE.

 

Download DuraVent Limited Lifetime Warranty here.

Documents & Files

Videos

Frequently Asked Questions

What are FasNSeal Flex's Specifications?


Applications

FasNSeal® Flex is for use with natural gas or propane Categories II, III and IV appliances or Canada’s Type BH Gas Vent Systems, having a maximum rated operating temperature of 480°F and a maximum positive pressure of 15” water column. FasNSeal® can be used on a wide range of applications, including: high efficiency gas boilers, furnaces, booster heaters, pool heaters, water heaters, unit heaters, or tankless water heaters.

 

Materials and Construction

Single strip double layer super-ferriticstainless steel (totalling .010″).

 

Diameters

FasNSeal® Flex 3″-12″

 

Listings

UL Listed to UL 1738 and UL 1777 and ULC S636.

What is FasNSeal Flex's Typical Installation?


Refer to our Typical Venting Installation drawings to select the appropriate component parts for your installation.

More Typical Installations:

1    Rain Cap
2    Storm Collar
3    Variable Pitch Roof Flashing
4    Vent Length
5    Adjustable Vent Length
6    Firestop/Flat Flashing
7    Horizontal Drip Tee
8    Elbow
9    Universal Condensate Drain
10    Appliance Adapter
11    Top Plate*
12    Male Flex Adaptere
13    FasNSeal Flex
14    Female Flex Adapter
15    Standard Tee

 

Commercial Applications

Commercial projects may require custom parts and unique system designs. DuraVent offers complete project assistance:

  • Engineering Services: Personalized system design services offer comprehensive CAD submittal drawing and complete bills of materials.
  • Custom Parts: If your project requires innovative solutions, contact DuraVent for custom parts that meet your specific project needs.
  • FasNSeal W2: FasNSeal W2 is the ideal choice for commercial applications where there is a need for low clearances to combustibles.
  • Up to 16” Vent Diameters: Many commercial applications require large diameter systems due to the units size and output. Large diameters are available in single and double wall, featuring FasNSeal’s triple lipped directional gaskets and built-in locking band which provides a safe and convenient installation.
What are the DuraVent product lines?


DuraVent offers the following product lines:

DuraTech 5″-8″: All-fuel, double-wall chimney system. UL 103 HT and ULC S604.

DuraTech 10″-24″: All-fuel, double-wall chimney system. UL 103.

DuraTech Canada is a double-wall, all-fuel chimney system for use with wood stoves, wood fireplaces, and other appliances using wood, oil, gas, or coal.

DuraPlus: Triple-wall all-fuel chimney with two layers of insulation.

DuraPlus HTC: Double-wall all-fuel chimney built to Canadian standards.

DuraChimney II: Double-wall air-cooled chimney for pre-fabricated masonry chimneys.

Combustion Air Systems: DuraVent’s exclusive, patent-pending system is designed to bring in outside combustion air directly to your wood or pellet stoves.

DuraBlack: Single-wall stovepipe.

DVL: Double-wall stovepipe.

DuraLiner: Double-wall factory insulated masonry relining system.

DuraFlex: Flexible stainless steel liners.

DuraFlex Aluminum: Flexible aluminum relining for masonry chimney. UL 1777 and ULC S635.

Ventinox: Flexible stainless steel liner.

CVS: Provides Ortal Branded Fireplace Systems and as a Direct Vent for Pellet Stoves.

PelletVent: Multi-fuel vent.

PelletVent Pro: Vents appliances using oil, wood pellets, corn, and other biofuels.

DirectVent Pro: Unitized, co-axial venting system for direct vent gas or propane stoves, heaters, and fireplaces.

Type B Gas Vent: Vents natural gas, liquid propane category I, and draft-hood equipped appliances

FasNSeal: Single, double-wall, flex, and concentric venting for category II, III, and IV appliances.

FasNSeal 80/90: Combined Category I and IV venting for Gas-Burning Appliances.

PolyPro: Single-wall, flex, and concentric venting made of polypropylene for category II and IV condensing appliances that operate up to 248 degrees.

PolyPro Flex: PolyPro double-wall flex lining system. Environmentally safe venting system for high-efficiency appliances, including water heaters, condensing boilers, and warm air furnaces. ULC S636.

DuraSeal: Single-Wall and Double-Wall Special Gas Vent Boiler Adapters.

DuraStack: A modular double-wall, positive pressure chimney for use with boiler breeching and stack, engine exhaust, and grease duct (DIS only)

DuraStack Pro: Models DIS and DAS. Modular Double-Wall Positive Pressure Chimney for Boiler Breeching, Stack, and Engine Exhaust.

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 75055095943

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Chingyuan
Waukegan, US
★★★★★ 5
Highly recommended!
Format: Hardcover
I first saw this book at a relative’s house and was immediately drawn in by its content. There’s no text at all, yet it captures children’s interest so strongly—especially when learning the concept of numbers. The illustrations are also beautiful. When my child didn’t yet understand numbers, it was still fun to recognize the animals or see what the characters in the pictures were doing. I really love this book.
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Reviewed in the United States on September 14, 2025
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KB
Los Angeles, US
★★★★★ 5
A Multi-faceted, beautiful book for babies through primary grades.
Format: Hardcover
Our second generation is now loving this beautiful, clever, playful book. Although there are no words, the story line is a delight. A watercolored village develops one page to the next starting with 0 and ending with 12. The pictures add one item in each category for each new number, building on the previous scene. Readers can find and count buildings, children, adults, pine trees, cherry trees, and an assortment of animals. In addition, in a lovely subtle manner, the four northern hemisphere seasons pass from January to December. The details of adult and child activities through time and seasons can be noted. Anno's creativity in this genre is unsurpassed. For my children, and now for my grandson, this book evokes fascination on several levels both aesthetic and intellectual. Start using it as a baby word book, and it will last as a joy throughout early childhood. Not every baby book must be a board book. Teaching children to turn pages gently is easy to do and adds to the amazing, shared experience.
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Reviewed in the United States on February 22, 2015
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Chopper
Cuba, US
★★★★★ 5
Gorgeous book!
Format: Hardcover
Read this over and over with my own children and they loved it. Buying for friends' children/grandchildren and they are loving it, too. Timeless, lots to capture kids' interest and counting. The suggested age is 3 and up, but we used it earlier than 3 years of age; it depends on the child. We're buying them now for newborns figuring they'll "grow into it."
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Reviewed in the United States on September 16, 2021
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Dan
Cuba, US
★★★★★ 4
A truly original concept picture book. Unlike most counting ...
Format: Hardcover
A truly original concept picture book. Unlike most counting concept books that only show one item type (like 2 balls on the page about 2) this book has many items to count on each number page (3 trees, 3 trains, 3 cows, etc, on the pages about the number 3). You have to search around to find each of the items because the author moves the items around each time. :) Yes, it's not as flashy, but it's got what really counts!
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Reviewed in the United States on December 3, 2016
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Elisa's Mom
Los Angeles, US
★★★★★ 5
Excellent early math book
Format: Paperback
I found this book on a recommended Early Math reading list posted on the PBS Parents website. Since there are no words in this book, there is nothing to actually read to your child. But it is likely one of the longest 12 page books I've read. And it is by far the most significant number book my 3 year old has read. Anno uses a town to depict and define numbers 0-12, the seasons, and the months of the year. The seasons and months are recognizeable, but not the focus like the numbers are. For the number 0, you see a blank landscape with a small river. When the child turns the page, he sees a large number 1 on the right side of the book and in the landscape one lone building, one tree, one sun, one snowman.... There is also a set of blocks on the left side of the book, with one block colored in. Thus, the child can see the number 1 represented as a numeral, as a block (of a set of 10), and as an object (one building, one tree, one person). As you turn the pages and the numbers increase, a village forms. The final page is the number 12 -- a full village at Christmas time, complete with 12 reindeer in the sky. As a parent, I enjoy having my daughter "read" to me. But I am most amazed by how the book has helped her to grasp the concept of numbers. As she explained, "0, Mommy. Because there's nothing there."
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Reviewed in the United States on March 1, 2009

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