Portable electric heaters, like all electric heaters, are 100 per cent efficient. They convert all the power they draw into heat. A typical 1,500-watt portable heater will warm 185 to 215 square feet of space. Portable heaters come in a wide variety of sizes and shapes: large or compact, upright or low contour, cube-shaped or low and narrow. Floor, baseboard and shelf models are available.

Electric space heaters are generally more expensive to operate than combustion space heaters, but they are the only unvented space heaters that are safe to operate inside your home. Although electric space heaters avoid indoor air quality concerns, they still carry hazards of potential burns and fires, and should be used with caution.

There are two basic types of portable electric heaters: convective and radiant. Radiant heaters emit infrared radiation from heat elements. Because radiant heaters warm people and objects rather than air, they are better for small area or spot heating. Convective heaters work by moving hot air around the room either by a fan or by encouraging natural air currents. They are the best choice for quickly warming larger spaces and keeping them warm.

When buying and installing an electric space heater, you should follow these general safety guidelines:

1. Electric heaters should be plugged directly into the wall outlet. If an extension cord is necessary, use a heavy-duty cord of 14-guage wire or larger.

2. For portable electric heaters, buy a unit with a tip-over safety switch, which automatically shuts off the heater if the unit is tipped over.