First, these are two different types of heaters that we found to be pretty durable and cheap. Also, both can run on 700 W, so if your place is old, it won’t blow the fuses so easily!
We live on the 3rd floor by the lake in Chicago. Our kitchen faces North and is practically all drafty windows, with no direct heating. In the winter, it can get really cold, so we use a portable convection heater that can run either 750 W or 1500 W. We use the 750W so we don’t blow the fuses in this old apartment. :-p
The heater is small but it heats up a room very quickly.
We also use this 700 W oil-filled radiator heater in the bedroom when it gets extra cold. It’s doesn’t use much electricity and still emits heat after it’s turned off.
Additionally, we save on our heating bill: we just put a heavy-duty plastic insulating sheet on the windows. We use the Duck Max Strength Heavy Duty Insulating Film Window Kit without the box. The thinner stuff is hard to put up because it clings annoyingly to everything like Saran Wrap.
You can get the box, if you want to spend more money, but it’s just cardboard: Max Strength Heavy Duty Insulating Film Window Kit with the box!
Makes a huge difference. We put them up the windows we don’t open every winter. We also get extra double-sided mounting tape, which can come in handy.