Space Heater Safety
Space heaters can be an excellent option for heating portions of a house, but they are not without risks. Space heaters can cause fires, diminish the quality of air within a home, cause burns if touched incorrectly, and increase the likelihood of mold infestations. Nonetheless, careful purchasing and use of a space heater can also result in years of efficient additional heat in a home.
One of the biggest risks associated with space heaters is fire. While these fires are less common than in the past, the Commonwealth of Massachusetts claims that one of every ten space heater fires results in a fatality. Most of these fires occur because homeowners left combustible materials like bedding or paper too close to the heater or placed a heater too close to carpeting or other flammable floor covering. To help prevent these fires, some heaters include a proximity sensor that automatically turns off the heating element if objects are judged too close for safe operation.
Worn outlets can also cause fires and other problems. Kristin Andersen, brand manager at Kaz, Inc. (a manufacturer of electric space heaters under the Honeywell brand) cautions that "Plugs can become very hot if they do not fit snugly into the outlet. If this occurs, the outlet may need to be replaced." Frayed and worn cords can also cause fires, as can extension cords which are not specifically rated for heavy use (12 or 14 gauge).
Children and pets playing too close to the heater can also cause problems. In addition to placing combustible materials in or near the heater and starting fires, children and pets can burn themselves by touching the heating elements or hot heater casings. Never leave a space heater unattended while in use, and consider purchasing heaters with casings that remain cool at all times.
Indoor Air Quality
While the risk of fire and burns is common to virtually all space heaters, those that use propane, natural gas, or kerosene, pose other concerns. Non-electric space heaters can significantly decrease the air quality within a home, especially if they are not attached to a vent or flue. Some of these heaters include sensors that test the oxygen levels in the surrounding air and automatically turn off the heater if the levels fall too low. However, even sensor features do not keep the furnace exhaust from entering the air. Opening a window near the heater will allow fresh air to enter the home and some of the noxious chemicals to leave it, making unvented heaters safer, but probably limiting the effectiveness of heating the room. Unvented heaters also pose a risk of increased carbon monoxide in a home and increased moisture that can cause mold, mildew, and bacteria which can both damage the house and possibly cause health problems for its occupants. Space heaters advertised as vent-free or ventless are best used in outdoor settings such as a porch, garage, or while camping.
Choosing a vented space heater with sealed combustion (meaning it both draws in and vents 100% of the air used outdoors) greatly reduce the risks of decreased air quality. Regularly replacing filters and inspecting flues and vents is importance maintenance on these types of heaters.