Yes, and I recommend it in sub-freezing weather. It will keep your water pipes from freezing, within limits. I've done it and was successful in weather in the teens, but would not rely on it for much lower temps.
"The further a society drifts from the truth, the more it will hate those that speak it." George Orwell
'08 34' SO, '12 Ram 2500 4X4, Big 6 cylinder sludge burner.