So I received the new air conditioner/ heater unit. It’s a heat pump not a heater. So an air conditioner takes air and transfers the heat outside and the cool inside. This unit basically reverses the process while in heat mode. It blows the cold air outside and the warm air is returned to the inside. Since the workshop isn’t heated while unoccupied it is very difficult for this unit to bring the temperature up to a comfortable level. The temperature recently has been between 15°F and 25°F. The workshop is mostly insulated but there are some significant issues with that. There is a fairly significant gap under most of the garage door. It also doesn’t have any weather stripping. Its an uninsulated sheet metal door. It transfers heat outside very effectively. That makes it very difficult to heat the space efficiently. I need to figure out how to get that door unsullied. But with the new unit and the space heater working together it is possible to raise the temperature despite the very low temperatures. Pretty sure if the outside temperature was above 32°F (freezing) the new unit could handle the task by itself. I think now if left only itself it would struggle to maintain a constant temperature.