What is the vent diameter specified for a chimney with corrugated liner?

What is the vent diameter specified for a chimney with corrugated liner?

• A. 3 Inch Diameter Vent
• B. 6 Inch Diameter Vent
• C. 4 Inch Diameter Vent
• D. 5 Inch Diameter Vent

Answer: (C)

Vent sizing hinges on matching the liner’s inside diameter to the appliance’s venting needs and ensuring the exhaust can flow freely. A corrugated liner inside a masonry chimney sets the actual passage area for flue gases, so the diameter must be large enough to prevent excessive backpressure and draft problems. For many common gas appliances installed with a corrugated liner, a 4-inch diameter provides a balance: it offers sufficient cross-sectional area for typical venting loads while avoiding the restrictions a smaller 3-inch liner would impose. Larger sizes like 5 or 6 inches are usually reserved for higher-Btu appliances or multiple venting paths, where extra capacity is needed, and can be unnecessary or problematic for standard setups. So, 4 inches is the standard, appropriate choice for a chimney with a corrugated liner.

Vent sizing hinges on matching the liner’s inside diameter to the appliance’s venting needs and ensuring the exhaust can flow freely. A corrugated liner inside a masonry chimney sets the actual passage area for flue gases, so the diameter must be large enough to prevent excessive backpressure and draft problems. For many common gas appliances installed with a corrugated liner, a 4-inch diameter provides a balance: it offers sufficient cross-sectional area for typical venting loads while avoiding the restrictions a smaller 3-inch liner would impose. Larger sizes like 5 or 6 inches are usually reserved for higher-Btu appliances or multiple venting paths, where extra capacity is needed, and can be unnecessary or problematic for standard setups. So, 4 inches is the standard, appropriate choice for a chimney with a corrugated liner.