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Type B Vent (Gas)

Metal Thickness

Pipe SizeInner PipeOuter Pipe
3", 4", 5", 6" round, and 4" oval.012".018" min
7" through 18" round, and 5" & 6" oval.014".018" min
20", 22", 24", 26", 28", 30" round.022".018" min


 ½ BTU per hour per square foot per degree F temperature differential. (U factor = 0.5)

Maximum Height 

Unlimited if properly supported.

Accepted By 


Listed By 

Underwriters Laboratories, Inc. to UL441 test standard

The new and improved AmeriVent Type B gas vent features a quick disconnect system.

To Connect: Snap-lock pipe and fittings together or align the seams, push together, and twist at least 1” to lock.

To Disconnect: Simply realign the seams and pull apart.

Locking Tab: To ensure a secure fit, push in the locking tab to lock the pipe together. (3" through 6")

To Connect-Locking TabTo Disconnect-Locking Bands

Product Description 

The Type B designation is assigned to gas venting systems that meet the safety requirements of Underwriters Laboratories, Inc.  The AmeriVent all-metal, double-wall gas vent is listed as Type B by Underwriters Laboratories, Inc. and is approved for such residential and commercial applications as Category 1 water heaters, boilers, furnaces, space heaters, or wall heaters.  UL-approved Type B gas vent products form a continuous passageway from an approved gas appliance to the termination of the vent above the roof of the structure.

For a perfect connection, all of the vent connector components and flexible lengths feature the proven AmeriVent snap-lock system of male and female connecting ends. This UL-listed system eliminates the need for cutting, crimping, fitting, or screw-fastening at the connector joints. Just install the appropriate tee or wye and the appliance adapters, and shape the flexible lengths to the space requirements of the job. The AmeriVent gas vent connectors system assures a perfectly accurate, top-performing installation the first time...all at significant savings in time and effort.

Double-Wall Construction

Double-wall metal construction provides protection for health and safety, as well as benefits of economy, ease of installation, efficiency, and protection from property damage. Designers of vent systems should take particular note of the fact that vents constructed of brick, cement, asbestos, and mass-insulated metal require lengthy warm-up periods, whereas double-wall metal vents reach operating temperatures almost instantly for rapid removal of the flue gases.

The AmeriVent System 

AmeriVent Type B gas vent uses a double wall of metal pipe for insulation and safety. The inner pipe of reflecting aluminum heats quickly, containing the warm flue gases inside. The airspace between the inner and the outer pipes provides insulation against heat loss to keep the warmer flue gases on the rise. The outer pipe of corrosion-resistant galvanized steel ensures strength, safety, and durability.

If the flue gases are kept rising at the proper rate, the structure is kept free from pollution, and condensation damage is eliminated. Although a large portion of the flue gas is composed of water vapor, AmeriVent Type B gas vent carries it out of the structure before it can condense.
One of the fire safety features of double-wall Type B gas vent is that its outer wall, insulated by the airspace beneath it, requires only 1” clearance to combustible material in the structure.

AmeriVent is a complete gas venting system, from 3” to 30” pipe diameters in 7 different pipe lengths, to single- to multi-appliance hook-ups. The AmeriVent gas vent line allows you to create almost any system from our more than 350 coordinated parts. Featuring Snap-Lock joints that are quick and easy to disconnect, the AmeriVent Type B gas vent system is lightweight with no sacrifice in strength, and is available in large sizes, adjustable components, and multi-story Type BW venting installation.

Specifications and Dimensions 

Available Pipe Sizes and Lengths 


Sizes: 3”, 4”, 5”, 6”, 7”, 8”
Lengths: 6”, 12”, 18”, 24”, 3’, 4’ (except 8” size), 5’

Sizes: 9”, 10”, 12”, 14”, 16”, 18”, 20”, 22”, 24”, 26”, 28”, 30”
Lengths: 12”, 18”, 24”, 3’


Sizes: 4”, 5”
Lengths: 6”, 12”, 18”, 24”, 3’, 4’, 5’

Size: 6”
Lengths: 6”, 12”, 18”, 24”, 3’


AmeriVent Type B gas vent is used for venting all
Category 1 listed gas appliances having draft hoods and
other appliances listed to be used with Type B Gas Vent.
For information on venting unlisted gas appliances or
appliances burning solid or liquid fuels, request our All-
Fuel Chimneys catalog.


Inner Wall: Aluminum Alloy 1100, 3003, or 3015
Outer Wall: Galvanized Steel