How does anyone know how many square feet a heater will heat? Unless they have inspected the house they will have not a clue. They ought to give ranges like "Will heat approximately 1000 sq ft of a home having R-13 walls, double pane windows, a vapor barrier, gasketed doors and a total permeable area not exceeding 4 inches square"! (Just to pile on what everyone else is saying) No device that will plug in a regular outlet will typically draw more than 1500 watts, this is because most circuts are 15 amp circuts, meaning that any more than 1500 would blow the breaker/fuse. So 1500 watts is all the heat you will get out of most electric heating devices. True a radiant heater may be slightly more comfortable in an drafty/uninsulated house, if you sit directly in front of it, because it will heat you before it heats the air, but it will make no difference in the abient temperature. So if you are interested in saving money on your electric bill, wear a sweater, no kidding, insulation/weather stripping would probably be a better investment.
