ULC-S636-08 Standard for Type BH Gas Venting Systems

The Standard covers the design, construction, and performance of gas venting systems intended for negative or positive pressure venting of gas-fired appliances producing flue gases having temperatures under the following:

(1) Class I venting systems are suitable for gas-fired appliances producing flue gas temperatures of more than 135°C but not more then 245°C;

(2) Class II venting systems are suitable for gas-fired appliances producing flue gas temperatures of 135°C or less;

(3) Class II venting systems are further classified into four temperature ratings as follows:

• (A) Up to and including 65°C;
• (B) Up to and including 90°C;
• (C) Up to and including 110°C; and
• (D) Up to and including 135°C.

Note: This Standard supersedes ULC-S636-95 Type BH Gas Venting Systems.