bimber wrote:
I've begun shopping for a new 4-season tent, as our old NF Looking at newer designs, ceiling vents seem to be popular. My experience with condensation, especially in temperatures at and below -15 C, is that its pretty much unavoidable.
Will ceiling vents significantly change this?
Does the size of the tent vs. number of sleepers make a huge difference? (I always felt like small 2 person tents tended to have more indoor snow than a larger 3 person with 2 people...)
Advice would be greatly appreciated!
Hi Bimber. No, ceiling ventilation will not make a huge difference, only a minor difference. Its not really a ventilation thing well below zero. As soon as moisture laden breath touches a cold surface, the moisture condenses and it flash freezes. On the way to the vent, anything the breath touches, it will freeze onto. A tent by definition just will not have a linear and fast air current going through it so that breath never touches any surface. Air swirls inside a tent, and air does not travel in straight lines anyway - it travels in helical flows, so it will not go "vent to vent" carrying all moisture with it, without detouring and touching surfaces. You can sleep in the open in total ventilation and your sleeping bag around the neck area will still be frosted due to your breath contacting the bag with each breath before it can escape to the air and be blown away.
That said, more ventilation will allow more condensed breath to escape before crystallizing onto a surface. But the air cannot move fast enough inside a tent for all of it to go directly to the vent. So ventilation is good, but it will have a limited effect.
Yes more sleepers means more moisture hitting the surface of the tent, bags, gear, clothing, etc.
If its not too windy or snowy, I suggest sleeping with the entire door fastened wide open to have a huge area for breath to escape. Using a bivy bag over your bag, or an overbag, will prevent the moving air from robbing heat from your inner bag. Unless its windy and blowing snow, you can get by with an A-frame tarp rig. When cold camping I use a conical tarp tent, floorless, and leave the door wide open unless its blowing hard and snowing.