我也是觉得 右边朝下的黑管 是 进气的。补充空气 的 锌皮管和室外相通,居然不加保温, 不可理解。
我的 furnace 是两个 白管 通室外,排废气, 进燃烧空气,进气的直接 连 燃烧室。
Direct-vent (two-pipe) system: The two-pipe system is most common in home heating applications. It provides a direct intake vent that brings outside air to the sealed combustion chamber with one...