this is what I have on mine. now I don't know what wattage I have, been to long. but I keep mine plugged in all the time. I go to fly, I unplug, fires right off. now the other day I didn't have it plugged in. was a little cold, like in the 30's and it farted and banged and broke my right side carb socket, oh and the throttle cable on the left side. learned my leason to keep it plugged in. it has a thermostate to shut it off when to a certain temp. you just need to read all the stuff. anyway this is what I have. I'm pretty sure I have the 150 watt.

http://www.reiffpreheat.com/Rotax912.htm