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DuraVent DuraFlex Stainless Factory Built Reline Kit: a metal chimney liner kit for a wood burning insert
The DuraVent DuraFlex Stainless Factory Built Reline Kit is a liner kit that goes inside an existing metal chimney when you add a wood burning insert to an old factory built fireplace. DuraVent identifies it as the only listed way to do this in the USA. DuraFlex Stainless is DuraVent’s flexible stainless steel liner, and this kit is its listed version for relining a metal factory built chimney. The liner is 6 inches across. Your existing chimney must measure at least 8 inches across the inside and no more than 14 inches across the outside.
This page includes a 25 foot liner coil. Choose DuraFlex 304, DuraFlex 316, or DuraFlex Pro for the liner in your kit. Pro bends more easily around turns in the chimney. The included centering bracket and ventilation disk hold the liner in position while leaving an air path open. The flexible liner needs no insulation in this application. Relining a brick or block chimney instead? See the DuraVent DuraFlex Pro Basic Kit for masonry chimneys. The DuraVent DuraFlex Stainless Factory Built Reline Kit ships free from My Cozy Outdoors with No Sales Tax (except WY) and the full manufacturer warranty.
Details
SKU: 6DFPRO-25KFB | 6DF304-25KFB | 6DF316-25KFB
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).
Instructions
Product Resources
Catalogs
Bulletins
- 2011 DuraFlex® Pro Most Flexible Chimney Liner On The Market Bulletin
- 2011 TherMix Chimney Liner Insulation Bulletin
- 2013 DuraFlex® – Relining a Factory-Built Chimney Can Now Be Done Safely With a Listed System Bulletin
- 2013 DuraFlex® Insert Adapter Bulletin
- 2017 Oil Sizing Chart Bulletin
- 2022 DuraFlex® 3″ – 8″ Removable Vertical Cap and Top Plate Bulletin
- 2022 DuraFlex® Custom Length Flex Liner Component Discontinuation Bulletin
Brochures
Sales Sheets
FAQ
What is the DuraFlex Factory-Built Reline Kit for?
It relines an existing factory-built (UL 127) fireplace chimney so a wood-burning insert can be installed safely; DuraVent says relining is critical for performance and safety in that case, and this is the first UL-listed reline system for factory-built chimneys with solid-fuel appliances in the USA. The kit is 6-inch and suits chimneys with at least an 8-inch inner and at most a 14-inch outer diameter.
What comes in the kit, and which liner should I choose?
A cap, storm collar, support bracket, ventilation disk, centering bracket, a 12-inch DuraLiner length, flex connector, a 25 or 35 foot flex length, an adjustable band and a flex adapter. The selector offers the liner in DuraFlex Pro (316, most flexible), DuraFlex 316 or DuraFlex 304; Pro is the listed price and the 304 and 316 options adjust it. Pick Pro for chimneys with offsets.
Which factory-built chimneys are covered?
DuraVent’s bulletin lists all UL 127, 103 and 103HT chimneys: insulated chimneys of any size with 2 inches of clearance, and air-cooled chimneys by diameter, for example up to 8-inch ID with at least a 1-1/4-inch wall (8 x 10-1/2 is fine) needing 1-1/2 inches of clearance, and larger chimneys with a 1-1/2-inch wall (10 x 13) needing 2 inches. Chimneys over 8 inches need 2 inches of clearance.
Does the flex liner need insulation in a factory-built chimney?
No. DuraVent’s factory-built reline bulletin states the flex does not need insulation in this application, unlike a masonry reline for wood where a 1/2-inch blanket is required for zero clearance. The ventilation disk and centering bracket in the kit keep the liner centered and the chimney’s air path open; follow the factory-built reline supplement (L253SUP-C) in the Instructions tab.
How is the liner installed and connected to the insert?
The flex is lowered through the old chimney, secured at the top with the support bracket, storm collar and cap, and joined at the bottom through the flex adapter and 12-inch DuraLiner section to the insert’s flue collar with the flex connector. Liner and old chimney must be inspected and cleaned first; DuraVent’s installation video is linked from the Instructions tab.
Which fuels and inserts can use it?
Wood-burning inserts are the intended use; the stainless liners are listed to UL 1777 for wood, gas, pellet and oil appliances, and the insert manual must permit installation in a factory-built fireplace with a listed liner. Match the 6-inch liner to the insert outlet. Other sizes and masonry kits are in the DuraFlex Stainless category.
Shipping / Freight / Return Info
Same-Day / 24 hour shipping
Same-Day/24 hour shipping - If we have the product in stock, we can ship same day if ordered before 12pm Monday - Friday (CST).Freight Claims Policy
- Open and inspect the order while the delivery driver is present. If delivery driver does not provide sufficient time to do so, please notate the delivery receipt.
- By signing the delivery receipt without noting any damage or missing items, you confirm that your order arrived complete and in excellent condition.
- Record any damage or missing pieces directly on the delivery receipt.
- Do not discard damaged item(s) or any original packaging. For severe damage, write “Refused due to damage” on the delivery receipt and contact us immediately.
- Report any damage within two business days, including delivery details and photos showing the issue
- Damaged item(s) must be returned within 30 days. Failure to return them will result in a charge to the original payment method.
Return Merchandise Authorization Policy
- Submit your return request within 30 days of delivery.
- You will receive an email within 1-2 business days confirming whether your return request has been approved or denied.
- Please also note that a 20% restocking fee may apply to approved returns
- If approved, you will receive an itemized Return Authorization, return shipping labels (if requested), and detailed instructions within 1–2 business days
- From the date this email is received, you will have 14 days to return the product.
- Once our distributor receives and inspects the returned item(s), your refund will be issued within 1–2 weeks
- Items returned outside of this process or time frame are not eligible for a refund.
Customer Reviews
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What Our Customers Say
D
A sauna turns your garden into a spa oasis. We debated it for a while, but after renovating our house, we pulled the trigger and bought a sauna from Norse Steam and Maya. She was always super responsive and helpful throughout the process. Don't kid yourself, getting a really nice sauna is not that easy. Sizing and heating need to be figured out, as does the building, but we have always had a helpful partner on our side. She never upsold us on anything we didn't need, and we got some nice freebies when the sauna was delivered. And now we can really enjoy every moment in our garden.
KF
I'm really happy with my sauna purchase. Maya gave above and beyond excellent customer service. She wasn't pushy and gave impressive followup after the delivery to make sure everything was just right.
DE
I enjoy my FD2 Sauna with Red Light, Infrared and radiant heat. Use it 5x a week and my post workout soreness is minimal and sleep great. Maya at Norse Steam was excellent to work with.
B
We purchased the 3-person sauna for our outdoor garden. We chose the cube sauna for the aesthetic and could not be happier.
I assembled by myself except for the 2 large panels (requires a few people). Instructions were good - took me two partial Saturdays to complete and a few hours to unpack and organize in advance of assembly. Had my elec. add a NEMA enclosure on the back for the controller and power for lights and a 2nd panel for the wireless control.
Customer service was excellent
MP
Awesome Sauna and Awesome Company and Experience purchasing it from Maya!
After much research I chose the Finnmark FD-2 and it has met and exceeded all my expectations! Easy to assemble and it functions great - just as advertised. I highly recommend it for home use!
EA
Recently purchased the Finnmark one person after much research. Extremely happy with it and the ordering process. Maya was very responsive and helpful during the process and keeping us updated while we waited for shipment. There were several places I could have ordered this, but i chose Norse Steam based on the communication and customer service which was fantastic. The shipment was also excellent. The setup was pretty seamless for two people - but the best part is the sauna experience 10/10
G
Maya is amazing - super helpful and responsive. Looked at many stores, these guys have the best prices and service. Highly recommend
GR
Norse Steam, and specifically Maya, were extremely helpful as I was making the decision for our Sauna. I was able to get all of the necessary details to make a decision as construction was happening in my backyard to make space for it.
We absolutely love the CL7G. It is extremely comfortable for 6 people (can fit more less comfortably). The Thermory Spruce and Aspen in the interior smells great. The lighting is lovely. We paired the CL7G with the Harvia Spirit 10.5kw.
RS
Had great experience shopping at Norse Steam for the new heater. They had very good deal, with rocks. Customer service was good, and responded very fast with my questions. Received the heater, and it looks good, and the quality seem to be great. Will install soon, and am very excited to start experiencing sauna the way it ment to be
O
positive purchase experience - Harvia Legend 150 SL woodstove
thanks Norse Steam for flawless transaction - I got instant replies on my questions, received competitive price on the wood stove and got it delivered within two weeks!
Can highly recommend Norse Steam for others.
JR
Smoking Hot Tub!
I got the Norse Steam SaunaLife wood-fired hot tub, the S4N model, and its been seriously great. It heats up quicker than I expected, usually around an hour and a half, and once its hot, it stays that way for a good long while. The wood-fired system is simple to use, and honestly kind of fun.
The tub itself feels solid and well put together. The thermo-spruce exterior looks beautiful in person, and the fiberglass interior is smooth, deep, and easy to clean. Its the kind of setup that just works without a bunch of fuss, which I really appreciate.
Also, the team at Norse Steam was genuinely great to work with. Super helpful, quick to respond, and made the process really easy from start to finish. It felt like they actually cared that I was happy with it. The tub has totally become a go-to way to unwind, and I wouldnt change a thing.
S
Maya was so knowledgeable and responsive
Maya was so knowledgeable and responsive. She helped me understand the product options and found a fantastic solution that fit our needs. Her follow through was very helpful and made us comfortable with our decision. We are extremely happy with the end result!
W
Great service
I recently purchased the Harvia Club sauna equipment, and I am thoroughly impressed with both the product and the customer service experience. The heaters robust performance and durable stainless steel construction make it ideal for larger sauna spaces, providing consistent heat and a relaxing environment. Its compatibility with advanced controls ensures a personalized sauna experience every time.
The customer service team was exceptional, prompt, knowledgeable, and helpful throughout the purchase process. They ensured smooth delivery and provided clear guidance on installation and operation. Overall, I highly recommend Harvia Club for anyone seeking premium-quality sauna equipment backed by excellent support!
BT
Great Sauna & Purchase Experience
Great experience purchasing Finnmark FD-2 from Norse Steam. Good communication and easy to assemble. Temperature increases quickly (30 minutes or less to 140) and maintains well. So far this has been a great purchase.
M
Great sauna and great customer service
We purchased the Finnmark SD-1 sauna. Maya was extremely helpful with the purchase. We had an issue with the sauna not reaching the maximum temperature, and Maya connected us with the appropriate technician that explained how to correct the issue. The sauna now heats to the maximum temperature (170 degrees) in less than an hour, and it is a great unit. We are very happy with it, and we would definitely purchase from NorseSteam if we needed any other items.
JK
Sauna Review
I recently purchased a sauna from Norse Steam, and I couldn't be more impressed with the entire experience. From start to finish, their customer service was exceptional, and Maya deserves special recognition for her outstanding support!
Maya was incredibly knowledgeable and patient, answering all my questions about the sauna features, installation process, and maintenance. She went above and beyond to ensure I selected the perfect model for my home. Even after the purchase, Maya followed up to make sure everything was running smoothly and that I was satisfied with my sauna.
The sauna itself is top-notch beautifully designed, durable, and easy to use. It's clear that Norse Steam takes pride in the quality of their products and their commitment to customer satisfaction.
If you're considering a sauna, I wholeheartedly recommend Norse Steam. With their excellent customer service and high-quality products, you're in great hands. Thank you, Maya, and the entire Norse Steam team for a fantastic experience!
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