We use a plug in cube heater. It tops out at 1500 watts which is about all a standard wall plug can handle. It works fine as long as you keep in mind to unplug it in the AM before using coffee pot, toaster, micro wave etc. If you are at a campground that only has a 20 amp power box you will "POP" the breaker for sure.
The Fireplace heater we have at home is also 1500 watts. I think the label on your heater will tell you that info.