Apparently you're correct, and I was misinformed. You could implement it this way—like how Tesla's newer designs can run the electric motor in a less-efficient

Apparently you're correct, and I was misinformed. You could implement it this way—like how Tesla's newer designs can run the electric motor in a less-efficient mode to provide heat for the battery pack—but the designs I investigated did have separate heaters as part of the circulation system. (For some reason the specs for these were not listed in the product summary, but rather only in the manual.)