What type of vent is not approved for gas?

What type of vent is not approved for gas?

• A. Type L
• B. Type K
• C. Type B
• D. Type M

Answer: (B)

Gas venting must follow listings and what the appliance manufacturer allows. If a vent type isn’t listed for use with a gas appliance, it isn’t approved for that purpose, even if it fits physically. Type B vent is not approved for gas because its listing specifies use with other fuel types or configurations not compatible with gas combustion products, so it cannot be used to vent a gas appliance. The other vent types are typically listed for gas venting in appropriate installations, so they’re acceptable when installed per their listings and the appliance’s instructions.

Gas venting must follow listings and what the appliance manufacturer allows. If a vent type isn’t listed for use with a gas appliance, it isn’t approved for that purpose, even if it fits physically. Type B vent is not approved for gas because its listing specifies use with other fuel types or configurations not compatible with gas combustion products, so it cannot be used to vent a gas appliance. The other vent types are typically listed for gas venting in appropriate installations, so they’re acceptable when installed per their listings and the appliance’s instructions.