There are a variety of different space heater designs available, and many of them are relatively safe to use. Choosing the safest space heater will typically involve looking for a number of features. Two important safety features include proximity sensors and switches that will cut the power if the unit tips over. One of the safest designs available is known as a radiant oil heater, since it operates by warming oil inside a sealed unit. Other radiant and convection heaters can be relatively safe as well, so long as they are used properly.
The two main types of space heaters are radiant and convection. A radiant heater is typically the safest space heater, and some variants are more dependable than others. Radiant designs may use heated substances such as oil or quartz to warm a space, and can include fins or other elements to provide more surface area. The defining feature of these heaters is that they do not use any sort of fan. Since there is no fan involved and no exposed element involved in a radiant unit, it will usually be the safest space heater available.
A convection unit may not be the safest space heater around, but they can be relatively harmless if used properly. Convection heaters typically use electrical resistance to warm up a metal or ceramic element. A fan may then draw cold air through the element and expel heated air into the room. Older units with relatively exposed metal heating coils can be potentially hazardous, though newer ceramic units are typically safe. If a ceramic convection heater is equipped with a temperature cutoff switch, tip over switch, and proximity sensor, it will often be very safe to use.
Certain designs may be considered unsafe or even dangerous. An old convection unit with an exposed coil that lacks any cutoff switches will never be considered the safest space heater. There are also some inherent dangers involved with gas operated heaters, as they may use an open flame to generate heat. It is usually a good idea to keep furniture and other objects away from any space heater, though it can be especially important when flames are involved.
Care should typically be taken to ensure proper ventilation any time a gas heater is used indoors. Gas heaters may create a number of potential hazards that can end in asphyxiation. A fuel leak combined with unventilated space might be an issue, as could a burning flame exhausting the available oxygen supply.