Space Heating: An Eye Toward Safety and Efficiency
December 14th, 2010 by Pam Blair

Space heaters work well as supplemental or zoned heat, rather than as a primary heating source, but keep safety in mind

Do not use or store flammable liquids near a space heater. The vapors can be ignited by the heater. Photo by Mike Teegarden

Do not use or store flammable liquids near a space heater. The vapors can be ignited by the heater. Photo by Mike Teegarden

An electric space heater can be an excellent source of supplemental heat for your home, increasing your comfort during cold months—especially in chilly garages, basements, workshops and other areas that may not have central heating.

But don’t blindly accept some manufacturers’ claims that they can significantly cut a home’s heating bill. Understand the advantages as well as the shortcomings of space heaters before deciding what is appropriate at your home.

And always pay attention to safety.

The U.S. Consumer Product Safety Commission estimates that more than 25,000 residential fires a year are associated with the use of space heaters, causing more than 300 deaths. About 6,000 people a year receive emergency room care for burn injuries associated with contacting hot surfaces of room heaters.

Operate Units Safely
Even though electric space heaters don’t have an open flame, the heating elements can get hot enough to ignite nearby combustibles. Periodically check surrounding objects—including carpeting and flooring materials—to see if they feel hot.

Underwriters Laboratories (UL) and the U.S. Consumer Product Safety Commission offer the following safety tips:

  • To prevent electrocution, always keep heaters away from water. Never use them in a bathroom or near a sink.
  • Keep space heaters at least 3 feet away from household combustibles.
  • Do not use extension cords, if possible. If absolutely necessary, use a heavy-duty cord of 14-gauge wire or larger.
  • Check for a secure plug/outlet fit. If the plug becomes very hot, the outlet may need to be replaced.
  • Inspect the cord for frayed wire or damaged insulation. Replace missing guards and controls. Never operate a defective heater.
  • Place the heater on a level surface and out of high traffic areas, where people could trip over it.
  • Do not use an electric heater as a dryer or to thaw pipes.
  • Do not place the heater where children or pets might play near it.
  • Buy a unit with a tip-over safety switch, which automatically shuts off the heater if the unit is tipped over, and an overheat sensor that shuts off the heater if it gets too hot.
  • Look for a model with a screen or grill around the heating coil to prevent kids from reaching inside or putting toys in the heater. Make sure the openings are small enough children’s fingers can’t get through to touch the heating element.
  • Maintain at least one working smoke detector on each floor.
  • Look for the UL mark. This means samples of the heater have met stringent safety standards.
  • Turn the space heater off when you go to bed or leave the room.

Maximizing the Benefits
Space heaters work best as a supplement to a furnace or heat pump. Rarely are they used as the primary heating source.

Before purchasing a space heater, determine how and where it will be used, and which type will do the job best.

Combination units are versatile, but you likely will get better performance from a radiant or convection heater. Use a radiant heater if you want heat instantly and will not move from one spot. To warm an entire room, choose a convection heater.

But can a space heater cut your home’s heating bill? Maybe, says Brian Sloboda, program manager specializing in energy efficiency for the Cooperative Research Network, a service of the National Rural Electric Cooperative Association.

Most space heaters use 600 to 1,500 watts of electricity. At medium power of 1,000 watts at 10 cents a kilowatt-hour, used eight hours a day, five days a week, it would cost $16 a month, Sloboda says.

But space heaters can only heat a small space. If you turn the thermostat of your central heating system down to as low as 50 degrees and place the space heater in a room that is occupied by people, then close that room off from the rest of the home, this method of “zone heating” will save money, Sloboda explains.

While space heaters have their place in warming a house, they cannot replace energy-efficient central heating or weatherization improvements to the home.

All electric space heaters produce one unit of heat for every unit of electricity consumed, meaning they are 100-percent energy efficient. Those that use natural gas are 80 percent efficient.

By comparison, geothermal heat pumps can produce more than three units of heat for every unit of electricity consumed, making them 300-percent efficient.

As with any technology, before buying a space heater, understand how the device is to be used, and understand the energy claims of the manufacturer.

While it technically may be possible to cut your heating bill by 50 percent using a space heater, it generally is impractical.

Choose the Right Style

Three main types of space heaters are available, and usually can be bought for $30 to $100: radiant heaters, convection heaters and combination heaters.

  • Radiant heaters

A radiant heater heats objects and people—not the air—in a room. They are best used in rooms where the person who wants to be warmed can be in direct line of sight of the heater. Radiant heaters can be a good choice if you are in a room for a short period of time and want instant heat. They can pose a burn or fire risk and should not be placed near furniture, drapery, pets or small children.

  • Convection heaters

Convection heaters are designed to heat the air—not people or objects—in a room. Hot air from the convection heater rises to the ceiling and forces cooler air to the floor. The cooler air is warmed by the heater and rises to the ceiling, creating a cycle that continues as long as the heater is on. These are typically either baseboard heaters or oil- or water-filled heaters. The oil- or water-filled heaters are the most efficient and typically look like a small radiator. Convection heaters are generally warm to the touch, but compared with a radiant heater, have a decreased fire and burn risk.

  • Combination heaters

As the name implies, a combination heater tries to bring the best of the radiant and convection heaters into one package. They often have an internal fan that aids in distributing heat throughout the room. These heaters are versatile and more common, although they typically do not perform as well as a radiant or convection heater.