The best diesel space heater will be the correct size for the space you need to heat and have an oxygen sensor with automatic shut off switch. Diesel fuel is relatively inexpensive, easier to store than natural gas, and an effective means of heating a space. Fuel burning space heaters are especially useful in areas which do not have electric power because they do not require electricity to operate.
The first step to choosing the correct diesel space heater is to calculate the volume of the area in cubic feet or meters. Measure the height, width, and length of the room or rooms to be heated. Multiply the numbers to obtain the number of cubic foot or cubic meters of the space. The heater should produce 30 to 60 British thermal units (BTUs) per cubic foot (90 to 180 BTUs per cubic meter). If the space is insulated with less than 3 inches (7.6 cm) of insulation in the walls or if the climate is particularly cold, use the higher end of the recommended range of BTUs.
Space heaters usually list the number of BTUs they can produce. They may also list the heat output in watts, but you can convert watts to BTUs by multiplying by 3.4. Choose a diesel space heater which produces approximately the same number of BTUs that you calculated for your space. Fewer BTUs will not adequately warm the space and too many will waste fuel and overheat the space. Units which produce more BTUs are typically more expensive than units that produce fewer, so it is more cost efficient to buy the smallest unit which will heat your space.
If the space is very large and you choose a heater which produces many BTUs, the unit may be compatible with a ductwork system. Units will indicate how many feet (or meters) of duct work they can support. Ducting is an effective means of transferring heat throughout a large space. A diesel space heater that uses ductwork usually includes a fan to blow the warmed air through the ducts. Look for a system which has a manual override and an automatic control for the fan.
There are disadvantages to using a fuel-burning space heater. Unlike electric space heaters, fuel burning heaters produce some carbon monoxide. This is a poisonous, odorless gas which can be fatal if inhaled for long periods of time. Fuel burning space heaters, like diesel space heaters, must be properly vented to prevent carbon monoxide from building up in the heated space.
A diesel space heater often comes with an oxygen sensor, which detects the level of oxygen in the air surrounding the unit. If the oxygen level gets dangerously low, the unit shuts down. Although a unit with a oxygen sensor may be more expensive than other units, this safety feature can save lives. For additional safety, a carbon monoxide sensor should be installed in the room with the space heater.