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Ohio State University Extension


Nonvented Portable Heaters

Small Farm and Gardening Safety and Health Series
Agriculture and Natural Resources
S. Dee Jepsen, Associate Professor and State Safety Leader, Agricultural Safety and Health, Food, Agricultural and Biological Engineering
Jeffery Suchy, Graduate Student and Lecturer, Food, Agricultural and Biological Engineering

Many farmers and gardeners use nonvented portable space heaters in shops, greenhouses, storage areas and other locations. These heaters may use electric heating elements or burn natural gas, propane or kerosene. They are usually freestanding and do not require ventilation to the outside. Special consideration must be given to avoid the possibility of electric shock, fire or poisoning caused by burning fuels in a closed environment.

Before using a nonvented portable heater give attention to:
• Location of the heater.
• Safety issues such as carbon monoxide poisoning and proper ventilation.
• Safety features such as a tip-over switch.

Safety Tips for Portable Electric Heaters

• Do not use a heater in damp or wet locations without the use of GFCI protection.
• Use only a heater with an automatic shutoff switch that shuts off the heater if it is tipped over or if it overheats.
• Make sure the insulation on the cord is not frayed or brittle, to avoid shock and fire hazards.

Portable Electric Heater

Safety Tips for Kerosene and Propane Heaters

• Make sure there is adequate ventilation when using kerosene and propane heaters. A heater that operates poorly could emit carbon monoxide.
• Be aware that carbon monoxide poisoning has symptoms similar to the flu. Symptoms could include nausea, chest pain, drowsiness, vomiting and confusion.
• Do not use kerosene or propane heaters in airtight areas. Crack open a window or door to allow air to enter.
• Keep interior doors open to help circulate air between rooms.

Kerosene Heaters

• Wait until the heater is cooled off before refilling it, to avoid fires. Do not overfill the tank.
• Use only K-1 kerosene. Never use any other type of fuel, as other fuels could cause a fire or an explosion.
• Store kerosene in a sealed blue container clearly marked “kerosene.” Never put it in a container that has held other fuels, such as gasoline. Even a small amount of gasoline in a kerosene heater can cause a fire.
• Make sure the wick is set at the proper height. A short wick can cause carbon monoxide levels to rise.

Propane Heaters

• Make sure that, if using a gas heater, it has an oxygen-depletion sensor. If there is a problem, this sensor will shut off the heater before carbon monoxide reaches dangerous levels.
• Make sure to, if the pilot light goes out, light a match before turning the gas on, to prevent the possibility of a flashback explosion.
• Do not ever try to light the heater if the smell of gas is present. If the smell of gas is detected, turn the heater off, open the doors and windows, and leave the building.


• “CPSC Safety Alert: Reducing Fire Hazards for Portable Electric Heaters.” U.S. Consumer Product Safety Commission. 2013.
• Jepsen, S.D., Michael Wonacott, Peter Ling, and Thomas Bean. Tailgate Safety Training for Landscaping and Horticultural Services: Non-Vented Heaters, AEX-192.1.33. Columbus, OH: Ohio State University Extension, 2006.

Reviewer: Kent McGuire, CFAES Safety and Health Coordinator, Food, Agricultural and Biological Engineering
Originally posted Nov 19, 2015.