The modern space heater is a designed and tested appliance, with safe guards to prevent tipping, overheating and producing poisonous carbon monoxide. Space heaters can be used with kerosene, natural gas and liquefied petroleum gas (LPG), commonly called as bottle gas, depending on the make. It is strongly recommended that no space heater of any type be operated in an enclosed area unless it is properly vented to a masonry chimney or prefabricated chimney. An unvented space heater in a closed space, even though properly maintained and operated, will surely produce carbon monoxide.