A torpedo heater generates heat from the combustion of fuel, such as kerosene, and then uses a fan to push the heated air out of the unit and into the space it is heating. Torpedo heaters are a simple form of portable heater and only require an electrical outlet and fuel.
The torpedo heater gets its name from its resemblance to a torpedo, but it is actually just a portable version of a forced air heater. Inside the unit there is a burner that gets ignited once the heater is turned on. Fuel, most often kerosene, is gravity-fed into the burner at an efficient rate where heat will continue to be made without burning too much fuel at once. The burning of the fuel creates a considerable amount of heat within the unit, and an electric fan pushes all of the heated air out of the unit into the surrounding air. To make the heater more efficient, the fans are typically put on a timer or sensor so that they will not continue to blow out air when there is no hot air inside the unit.
When kerosene burns, it creates a lot of heat but sometimes does not smell very pleasant. For this reason, some heaters also can burn diesel, propane or other fuels. Torpedo heaters can be used indoors or outdoors, but they should never be placed near something flammable.