EC135 / EC145   

Its only a 15amp circuit run with 14 gauge wire so while that will take care of any space heater that is 1800watts or less the continous draw for an item like that can and will find the slightest defect in the design of that system.  Its just easier to avoid it and go through the window.  Use a high quality 12 gauge extension cord since you are probably using a 100' cord to get away from the building to avoid voltage drop.  Also spend the money to get a well made heater, saving a few dollars on a $40 space heater vs an $80 is not what to do when those things catch fire and torch a multi-million dollar aircraft to the ground.  See diagram below.