DuraVent’s innovative system for a lock-tight connection for Type B Gas Vent called DuraLock. See the alignment indicators meet; feel the ends grasp together; hear the snap as the connection firmly locks into place.
DuraVent Type B Gas Vent is designed to meet the rugged demands of the job site. The inner wall is recessed to eliminate damage in handling.
Type B Gas Vent has been engineered to heat up rapidly. It remains hot during the operation of the appliance with minimal condensation in the appliance and vent system. Pipe lengths are available in multiple lengths, 6 to 60 inches, with a full complement of adjustable and rigid fittings.
Type B gas vents are not suitable for use with wood-burning or coal applications, industrial ovens, exhaust ranges and hoods, grease or pollution ducting, or as free-standing exhaust vents for high-temperature applications.
DuraVent’s Type B Gas Vent system. Use with natural gas or liquid propane category I and 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
Round Type B Gas Vent 3″ – 8″ and oval 4″ – 6″: Aluminum .012″ inner wall, galvanized .018″ outer wall. Round Type B Gas Vent 10″ – 16″: Aluminum .016″ inner wall, galvanized .021″ outer wall. Round Type B Gas Vent 18″ – 3″: aluminum .020″ inner wall, galvanized .021″ outer wall. 3″-16″ diameters feature twist-lock fittings, screws required for 14″ and larger diameters.
1″ clearance to combustibles in single and multi-family dwellings.
3″- 30″ Round Diameter. 4″, 5″ and 6″ Oval.
UL Listed to UL 441 and UL 1777 (MH6357). ULC Listed to ULC S605 (CMH1276 & CMH1407).
Refer to our Typical Venting Installation drawings to select the appropriate component parts for your installation.
More Typical Installations:
|10||Female Flex Adapter|
|15||Draft Hood Connector|
|16||Square Firestop Support|
|18||Oval to Round Adapter|
|20||Oval Tee Cap|
|21||Oval Tee Support|
|22||Oval Firestop Spacer|
|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 lo0se 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.
|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||—|
- 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.
- Unit Heater Kits Sales Sheet (PDF, 2MB )
- Type B Gas Vent Specification Sheet (PDF, 136KB )