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DuraVent DuraFlex Aluminum Liner Kit: the liner and chimney fittings in one box
The DuraVent DuraFlex Aluminum Liner Kit is a chimney relining kit with 25 feet of flexible aluminum liner. It includes a cap that supports the liner, a plate that seals the chimney top, and a mortar sleeve that lines the opening through the chimney wall. DuraFlex Aluminum is DuraVent’s flexible aluminum liner for relining a masonry chimney that vents a gas appliance. It serves natural gas or propane appliances with a draft hood, which admits air into the vent, or approval for Type B gas vent pipe. These include compatible gas fireplaces, furnaces, boilers, and water heaters.
Choose a diameter of 3, 4, 5, 5 1/2, 6, 7, or 8 inches. The liner extends 4 to 5 inches above the chimney top. The cap clamps around it and carries its weight. Allow for the separately purchased liner pulling tool, rope, sealant, anchors, and fitting that connects the liner to the appliance’s vent pipe. DuraVent calls for inspection each year. A taller chimney needs another coil and a coupling to join them. Need that extra coil? See the DuraVent DuraFlex Aluminum Length liner coil. The DuraVent DuraFlex Aluminum Liner Kit ships free from My Cozy Outdoors with No Sales Tax (except WY) and the full manufacturer warranty.
Details
SKU: 3DFA-25K | 4DFA-25K | 5DFA-25K | 55DFA-25K | 6DFA-25K | 7DFA-25K | 8DFA-25K
Applications
DuraFlex AL (DFAL) aluminum flexible relining for masonry chimney. Use with natural gas or liquid propane category I, draft hood equipped appliances, and appliances tested and listed to use Type B Gas Vent. Applications include: natural gas fireplaces, gas-fired furnaces, boilers, water heaters, and wall or space heating applications
Materials and Construction
Single-wall .010″ aluminum (2-ply of .005″).
Clearances
0″ clearance to masonry.
Diameters
3″, 4″, 5″, 5.5″, 6″, 7″, and 8″
Listings
Listed to UL 1777 and ULC S635.
Instructions
Typical Installation
Refer to our Typical Venting Installation drawings to select the appropriate component parts for your installation
More Typical Installations:
Installation Key
| 1 | DuraCap |
| 2 | Storm Collar |
| 3 | Roof Flashing |
| 4 | High-Wind Cap |
| 5 | Round Pipe |
| 6 | Elbow |
| 7 | Tee |
| 8 | Tee Cap |
| 9 | Increaser Tee |
| 10 | Female Flex Adapter |
| 11 | Male Adapter |
| 12 | Double-Wall Wye |
| 13 | Pipe Collar |
| 14 | Increaser |
| 15 | Draft Hood Connector |
| 16 | Square Firestop Support |
| 17 | Oval Pipe |
| 18 | Oval to Round Adapter |
| 19 | Oval Tee |
| 20 | Oval Tee Cap |
| 21 | Oval Tee Support |
| 22 | Oval Firestop Spacer |
| 23 | DuraConnect II |
| 24 | DuraFlex AL Length |
| 25 | DuraFlex Motar Sleeve |
| 26 | DuraFlex AL Coupling |
How Size and Height Affect Stove Performance
- The amount of heat the vent gases loose as they flow determines how much condensation will occur and how strong the draft will be. To control the heat loses, proper selection of venting materials is of vital importance.
- Double-wall Type B Gas Vent, with an aluminum inner wall and a galvanized steel outer wall, has proven to be the ideal choice in venting materials.
Vent Termination Chart
Using listed Type B Gas Vent caps may terminate in accordance with this table.
| Minimum height | ||
|---|---|---|
| Roof Pitch | Feet | Meters |
| Flat to 7/12 | 1 | 0.30 |
| Over 7/12 to 8/12 | 1.5 | 0.46 |
| Over 8/12 to 9/12 | 2 | 0.61 |
| Over 9/12 to 10/12 | 2.5 | 0.76 |
| Over 10/12 to 11/12 | 3.25 | 0.99 |
| Over 11/12 to 12/12 | 4 | 1.22 |
| Over 12/12 to 14/12 | 5 | 1.52 |
| Over 14/12 to 16/12 | 6 | 1.83 |
| Over 16/12 to 18/12 | 7 | 2.13 |
| Over 18/12 to 20/12 | 7.5 | 2.29 |
| Over 20/12 to 21/12 | 8 | 2.44 |
Gas Vent Specification Chart
| Item | Clearances | Maximum Height | Outer Tube Ø | Materials | Locking Device | UL Listing | ULC Listing |
|---|---|---|---|---|---|---|---|
| Type B Vent Round 3″-8″ | 1 inch to combustibles | 100 feet | 5/8″ larger than ID | Inner – .012″ Aluminum Outer – .018″ Galvanized | DuraLock | MH6357 | CMH1276 |
| Round 10″ to 16″ See note 2 | 1 inch to combustibles | 100 feet | 1″ larger than ID | Inner – .016″ Aluminum Outer – .021″ Galvanized | TwistLock Screws | MH6357 | CMH1276 |
| Round 18″ to 30″ | 1 inch to combustibles | 100 feet | 2″ larger than ID See note 5 | Inner – .020″ Aluminum Outer – .021″ Galvanized | Screws | MH6357 | CMH1276 |
| Oval Type B Vent 4″ and 5″ | 2″ x 4″ & 2″ x 6″ stud wall and 1 inch to combustibles | See Note 3 | 2 1/2″ x 7 1/4″ 3 1/8″ x 10 7/8″ | Inner – .012″ Aluminum Outer – .018″ Galvanized | Button Lock | MH6357 | CMH1276 |
| Oval Type B Vent 6″ | 2″ x 6″ stud wall and 1 inch to combustibles | See Note 3 | 3 1/4″ x 12″ | Inner – .012″ Aluminum Outer – .018″ Galvanized | Button Lock | MH6357 | CMH1276 |
| Type B Vent 3″ to 6″ Round Liner” | 0″/Masonry | 50 feet | 5/8″ larger than ID | Inner – .012″ Aluminum Outer – .018″ Galvanized | DuraLock | MH14420 MH6357 | CMH1407 |
| DuraFlex AL Gas Relining 3″ to 6″ | 0″/Masonry | 50 feet | 1/4″ larger than ID | .010″ Aluminum Flex | Screws DuraLock | MH14420 | — |
| DuraConnect 3″ to 6″ | 1 inch to combustibles | See Note 4 | 1/4″ larger than ID | .010″ Aluminum Flex .018″ Galvalume | DuraLock | MH14089 | — |
| DuraConnect II 3″ to 6″ | 1 inch to combustibles | See Note 4 | 1/4″ larger than ID | .010″ Aluminum Flex .018″ Galvalume | DuraLock | MH14089 | — |
Note:
- Clearance to combustibles is the air space between vent and combustibles.
- Maximum height varies with equipment over 50′, for taller applications refer to SDV sizing handbook (L202). 14″-16″ Pipe require screws.
- When oval is used on wall furnaces, minimum height required from bottom of furnace to cap is 12′, minimum 16″ stud space.
- Limited by sizing tables.
- 18″ pipe OD is one inch larger than ID and 20″ – 30″ OD is 2″ greater than ID
FAQ
What is in the DuraFlex Aluminum Kit?
A DuraFlex AL flex length, a DuraFlex AL Cap, a DuraFlex Top Plate and a DuraFlex Mortar Sleeve, the parts to reline a masonry chimney for a gas appliance from crown to thimble. Flex lengths of 25 or 35 feet are offered and the diameter, 3 to 8 inches, is chosen on the selector; the 3-inch kit is the listed price.
Which gas appliances can vent through it?
Natural gas or propane Category I draft-hood appliances and appliances listed for Type B gas vent: gas fireplaces, furnaces, boilers, water heaters and wall or space heaters. It is not for wood, pellet, oil or condensing (Category II, III, IV) appliances, which need a stainless liner or special gas vent. The appliance manual must permit a listed aluminum liner.
What is the liner made of, and what clearance does it need?
Single-wall .010-inch aluminum made of two .005-inch plies, listed to UL 1777 and ULC S635 at zero clearance to the masonry. It protects the chimney from the condensation of gas flue products. Follow the fuel gas code vent tables for sizing and the 50-foot height rating in DuraVent’s gas vent chart.
How is it installed?
The flex is drawn down the flue, the Mortar Sleeve seals the thimble opening where the liner meets the appliance connector or B vent, and the Top Plate seats on the crown with the liner clamped and the cap fitted. Per DuraVent’s L219 instructions, flex sections join with couplings and screws, and a Female Flex Adapter or B-vent adapter makes the bottom connection.
How tall does the cap need to be above the roof?
For a listed Type B cap the termination chart on the page applies: 1 foot above the roof up to a 7/12 pitch, 1.5 feet to 8/12, 2 feet to 9/12, and up to 4 feet at 12/12, with the fuel gas code governing. Extra flex, couplings, adapters and a flex puller are on the DuraFlex Aluminum configurator.
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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