I've used a space heater for years only during the coldest parts of winter even though I keep my van garage kept. I normally only set a ceramic heater to 500 or 750 watts, never on high. I just try to make sure it's above freezing inside my van, not toasty warm. If I was forced to keep my van outside I'd be afraid to use a space heater and would be forced to winterize the machine. I think setting one on high for extended periods of time is an accident waiting to happen. It has to get pretty cold outside for me to worry about. February is my main month of concern here almost every year since I've been in business.Space heaters can save your heat exchangers but can also demolish your van, TM and home.