I have a 381 and about the same temp, maybe lower (seen 17 and 19 once and a few 25) and I go through one of the 30's every 5-6 days, but then again I have 50A so I supplement a bit by running the fireplace. If the temp gets to 45 or better, which is not often, I run the heat pump. I would think that you are burning about what could be expected.
__________________
2019 HC 381TH
2021 Ram 3500 6.7 HO
|