What is the maximum horizontal length allowed for a Type B double-wall vent connector?

The maximum horizontal length allowed for a Type B double-wall vent connector is indeed 100% of the chimney height. This guideline is established to ensure that the venting system operates efficiently and safely. A Type B vent connector is designed to handle higher temperatures and is intended for use with gas appliances. Allowing a full 100% of the chimney height for the vent connector helps maintain adequate draft and prevents issues such as backdraft or insufficient ventilation.

By adhering to this maximum length, the system ensures that combustion gases are effectively expelled outside, while also minimizing the potential for condensation and related problems. This is crucial for maintaining the proper functioning of gas appliances and ensuring safety within the residential or commercial structure.

Other options suggest lower percentages of the chimney height, which can lead to complications in airflow and draft that could negatively impact system performance. Such limitations are not necessary, as the double-wall design of Type B vent connectors is robust enough to handle the full height in acceptable scenarios.