I have used them as has our “neighbors” from Michigan…. Result…. Unreliable at 9000’ even if you allow a breeze to blow thru your tent (even a canvas wall tent), it is not a CO2 sensor as I understand it, it is a low oxygen sensor and at altitude you are already low on oxygen. Intermittant, unreliable heat source. We have had cold neighbors come visit us to thaw out because they relied soley on Buddy Heaters for heat. Not fit for use as the only source of heat on acold weather elk hunting trip in my opinion.

On occasion I have used a 7x9 dome tent (two men) on Winter Elk Hunts, either in spike camp or as highly mobile truck set up, and we use the straight Mister Heater and a Carbon Monoxide detector placed at bunk level. With some tent zips open just a little, we use it to warm the tent (and ourselves --- “recharge” is critical) in the evening hours as we eat and get ready for bed. We position the heater so we can turn it on and off from our cot. We shut it off for sleeping (close the zips clear shut) and then when the alarm clock goes off in the morning we light the Mister Heater from bed, let it go 5 minutes and things are warm as toast, open some zips and get dressed and eat breakfast. Leave camp warm and happy.

Some folks are pushing “just get a warmer bag”, IMHO if you are hunting elk hard day after day in challenging terrain, at altitude, and in the weather you will NEED the warm evening hours and comfortable morning launch hours to keep up both your spirits and your stamina. A bag alone, night after night, day after day with no heat is essentially unworkable for all but the “iron men” i.e. 1% of hunters.