Which diameter vent corresponds to a capacity of 122 MBtu/h before reduction?

Which diameter vent corresponds to a capacity of 122 MBtu/h before reduction?

• A. 5 inch diameter vent
• B. 6 inch diameter vent
• C. 4 inch diameter vent
• D. 7 inch diameter vent

Answer: (A)

Vent diameter determines how much gas input a vent can carry before reductions are applied; bigger diameters mean higher capacity on the standard venting chart. For a capacity of 122 MBtu/h before reduction, the chart shows that a 5-inch diameter vent matches that value. A smaller diameter would show a lower capacity, while a larger diameter would show a higher capacity, so they wouldn’t align with 122 MBtu/h before reduction. So, the 5-inch vent is the correct size.

Vent diameter determines how much gas input a vent can carry before reductions are applied; bigger diameters mean higher capacity on the standard venting chart. For a capacity of 122 MBtu/h before reduction, the chart shows that a 5-inch diameter vent matches that value. A smaller diameter would show a lower capacity, while a larger diameter would show a higher capacity, so they wouldn’t align with 122 MBtu/h before reduction. So, the 5-inch vent is the correct size.