What is required for the vent pipe in a horizontal venting arrangement of a high-efficiency condensing furnace?

In a horizontal venting arrangement of a high-efficiency condensing furnace, it is essential for the vent pipe to be airtight and supported to ensure optimal performance and safety. High-efficiency condensing furnaces generate water vapor as a byproduct of combustion, which can condense within the venting system. An airtight vent pipe eliminates the risk of flue gases escaping into the living space and ensures that the condensate produced can be effectively drained away or managed.

Moreover, proper support is critical to maintain the integrity and alignment of the venting system throughout its length, preventing sagging or misalignment that could lead to blockages or leaks. This is particularly important in horizontal venting, where gravity affects the flow of condensate, and an unsupported pipe may lead to water pooling, restricting venting effectiveness.

In contrast, having a flexible vent, insulation, or a removable design would not address the key requirements for airtight connections and structural support necessary for safe operation in any high-efficiency condensing furnace setup.