A Type L vent requires how many inches of clearance to combustibles?

A Type L vent requires how many inches of clearance to combustibles?

• A. 9"
• B. 6"
• C. 12"
• D. 3"

Answer: (A)

Clearance to combustibles means the minimum distance required between the Type L vent and any combustible material (like wood framing or insulation) so heat from the vent won’t ignite it. Type L vent systems are designed for gas appliances that run cooler than older, higher-heat vent types, but they still radiate heat. The installation listings for Type L vent specify a minimum of 9 inches of clearance to combustibles. This larger spacing accounts for heat transfer through surrounding materials and ensures a safe margin in typical wall and attic assemblies. Unless a manufacturer-approved shield or noncombustible chase is used that reduces the clearance per the listing, you must maintain about 9 inches on all sides. The smaller distances don’t meet the standard listed protection, so they wouldn’t be acceptable in a normal Type L installation.

Clearance to combustibles means the minimum distance required between the Type L vent and any combustible material (like wood framing or insulation) so heat from the vent won’t ignite it. Type L vent systems are designed for gas appliances that run cooler than older, higher-heat vent types, but they still radiate heat. The installation listings for Type L vent specify a minimum of 9 inches of clearance to combustibles. This larger spacing accounts for heat transfer through surrounding materials and ensures a safe margin in typical wall and attic assemblies. Unless a manufacturer-approved shield or noncombustible chase is used that reduces the clearance per the listing, you must maintain about 9 inches on all sides. The smaller distances don’t meet the standard listed protection, so they wouldn’t be acceptable in a normal Type L installation.