[TDW]

Mark...If you have forced air heating system, why don't you pipe a couple of ducts to the garage? That will be plenty of heat to keep things dry. I have 1 duct going to the 2 car house garage where the wife parks. No problems at all with it. Some local laws may need to be circumvented, but it's your house. If you let a car sit ideling for 3 days, you may get some carbom monoxide thru the ductwork. If you are that concerned about CM, put some flapper valves in the ducts.