We put an Espar S2 D2 and on the lowest setting our AT Summit stayed warm enough for us to both kick off the blankets in the middle of the night, and the best part was no condensation- the temp was 14F over night, snow on the ground all weekend. We had the propane heat in our 2017 Fleet, and at the same camp in similar weather with the heat on all night, it was "raining" on us inside, everything was wet even with two fans running to exhaust moisture from our breath. I will forever more be a customer of the forced air type heater like S2 D2.