Carl,
I think it was the Forum Moderator / Hurricane expert, Mr. Farris, who in a post months/years back that detailed the temps that the Comfort Hot (CH) would be effective, definitely not as effective as the Hurricane. If I recall right, the CH was iffy at below freezing temps; satisfactory at ~40 degrees. Recently, on 8 to 30 degree days, my limping CH (only 1 of 2 elements working) barely kept the coach temp above freezing. On our 1 (& only) sub-freezing holiday trip years back, we stayed warm using radiator style space heaters as I had no handle on the workings of the Hurricane or CH.