The minimum clearance from combustible construction for a single wall metal vent connector serving a furnace listed for use with a Type B vent is ______ inches.

The minimum clearance from combustible construction for a single wall metal vent connector serving a furnace listed for use with a Type B vent is ______ inches.

• A. 4
• B. 6
• C. 2
• D. 3

Answer: (B)

The main idea is to protect any combustible materials from the heat of the vent. A single-wall metal vent connector carries hot combustion products and has no insulation, so it must be kept away from combustibles. For a furnace listed to vent through a Type B system, the required minimum distance is six inches. This clearance helps prevent ignition of nearby wood, insulation, or other combustible construction if the pipe gets hot or if there’s a venting fault. Smaller distances (such as four, two, or three inches) would not provide enough separation to keep combustibles safe under normal operation, which is why six inches is specified. If a tighter fit were ever needed, it would involve approved protective measures or a different, properly rated venting arrangement, but with a single-wall connector this six-inch requirement is the standard.

The main idea is to protect any combustible materials from the heat of the vent. A single-wall metal vent connector carries hot combustion products and has no insulation, so it must be kept away from combustibles. For a furnace listed to vent through a Type B system, the required minimum distance is six inches. This clearance helps prevent ignition of nearby wood, insulation, or other combustible construction if the pipe gets hot or if there’s a venting fault. Smaller distances (such as four, two, or three inches) would not provide enough separation to keep combustibles safe under normal operation, which is why six inches is specified. If a tighter fit were ever needed, it would involve approved protective measures or a different, properly rated venting arrangement, but with a single-wall connector this six-inch requirement is the standard.