I recently hooked up my outside air vent on my Harman XXV. I noticed right away that the outside air pipe frosted up. Just wondering if anyone has had any problems in extreme cold. I could imagine problems with frost buildup restricting air flow or maybe lost efficiency with air that is too cold. I run the stove pretty much 24/7 on room temperature mode and it keeps 1800 sq. ft. at 74 even at -40 outside. I figured that hooking it up would reduce outside air coming in, but I don't want to create new problems.