In the first few years of our existing house, I struggled in various ways to vent the bathroom shower upstairs. Everything I tried led to condensation and ice problems. Even with double R-19 cotton floss over galvanized ventilation ducts, I still encounter problems of condensation and freezing. Are there any proven solutions to this problem of cold weather condensation when we are preparing to build a new house? It's a good question, because it's not something I often see doing well. Before we get some specific suggestions about pipeline installation in cold weather, let's start with some basic pipeline suggestions.

　　建議我們的客戶盡可能地將他們的浴室風扇從山墻墻上吹出。如果您通過屋頂排氣，冷凝水會滴回到內部。如果您通過拱頂通風，通常位于閣樓通風口，水分將被吸回到閣樓或屋頂通風口。使用剛性金屬管道（鋁或鍍鋅鋼），縱向接縫朝上，接頭用鋁箔膠帶或管道膠泥或剛性塑料管密封。務必使管道傾斜一點，以便排出外部。剛性管道優于柔性管道，較大的管道是優選的，特別是如果運行較長。佳做法是將整個鍍鋅通風管道用R-3包裹到R-8絕緣層，但是，如果沒有別的，你應該少將6英尺的管道包裹在終點內，這是有可能發生冷凝的地方。保持通風口低，并在管道上運行絕緣層。

　　It is recommended that our customers blow out their bathroom fans from the wall as much as possible. If you exhaust through the roof, the condensate will drip back inside. If you ventilate through the vault, which is usually located in the attic vent, moisture will be sucked back into the attic or roof vent. Use rigid metal pipes (aluminium or galvanized steel) with longitudinal joints facing upward, and the joints are sealed with aluminium foil tape or pipe cement or rigid plastic pipes. Be sure to tilt the pipe a little so that it can be discharged from the outside. Rigid pipes are superior to flexible ones. Larger ones are preferred, especially if they run longer. Best practice is to wrap the entire galvanized ventilation duct in R-3 to R-8 insulation, but if nothing else, you should wrap at least 6 feet of duct in the end, which is the most likely place for condensation. Keep the vent low and run the insulation layer on the pipeline.

　　對于外部通風口結冰的問題，相對濕度為25％（相當低）的70°F室內空氣將在33°F冷凝，因此在寒冷天氣會發生冷凝。用風扇推110立方米。每分鐘英尺，空氣溫度為80°F，相對濕度為80％，正如您在使用漂亮的蒸汽淋浴時所做的那樣，在10分鐘的淋浴時，當它在外面25°時，你會產生幾乎3/4杯的冷凝水。

　　For the freezing problem of the external vent, the 70 degree F indoor air with 25% relative humidity (quite low) will condense at 33 degree F, so condensation will occur in cold weather. Push 110 cubic meters with a fan. At a foot per minute, the air temperature is 80 degrees F and the relative humidity is 80%. As you do with a beautiful steam shower, in a 10-minute shower, when it's 25 degrees outside, you produce almost three-quarters of the condensed water.