How to Safely Operate Portable Space Heaters

Portable space heaters are quite affordable these days to buy, and popular among college students in cold dorms, apartment dwellers with that one colder-than-usual work area to heat up, and home owners that just haven’t gotten around to fully insulating all their rooms.

These units offer rapid spot heating and can compensate to a degree for drafty windows, faulty door seals, insufficiently sized central furnaces, and inadequate insulation in walls, floors, and ceilings.  Plus, if you don’t use too many of them too often, they can actually save you money on your heating bills, as they permit heating of a small area in your living space while turning down the central heating for the rest of the house. Yet these space heaters often contribute to the causes for serious skin burns, house fires, property damage, and unfortunately, death.  Typically, these accidents happen because the user is unfamiliar with the safest practices, advice, and tips for heater placement, operation, maintenance, and replacement.  It’s common for people to die of carbon monoxide poisoning due to a gas space heater operating in bedrooms, or in any enclosed space without enough ventilation.  Improper heater placement often causes furniture and drapery fires, and outdated wiring can overheat when someone plugs an electric space heater into these antique power circuits.  Kerosene space heaters have their issues too.  Many emit unhealthy fumes if lower grades of, or the wrong fuel altogether are burned in them.  Plus, any liquid fuel portable space heater can be knocked over, triggering fuel spills and potentially BIG, quickly-growing fires. By far, the vast majority of injuries and loss of life involving portable space heaters, happens because people simply never took the time to learn how to pick the safest units while shopping for one, or how to safely operate them once they get them home.  So in this piece, we offer lots of safety tips and advice for the proper placement, operation, fuel handling, and maintenance of these heating units, of both electric and combustion types of heaters.

Tips and Advice for Safest Portable Space Heater Operation

General Advice and Hints for All Space Heater Types

Choose the right sized heater for the job.  Electric space heaters typically output a maximum of 1875 watts of heat when set on the highest setting.  So it’s hard to go wrong when buying one of these, so long as they have an adjustable thermostat and / or high and low heat output settings.  However, the combustion type heaters vary much more in their maximum BTU output.  So, check on their boxes and cartons, for their intended room sizes, and avoid choosing excessively large or insufficiently sized heaters for your heated space.  Improper sizing can result in frequent on-off heater cycling, wide and rapid temperature swings (where the room becomes unbearably hot, and then becomes too cold once the heater shuts off), or the heater may run all the time, not being able to meet comfort demands in the space.

Buy only UL approved space heaters.  Underwriters Laboratory (UL) approved space heaters have been put through rigorous testing to ensure compliance with long-established safety regulations and guidelines.  This seal therefore, means that the heater is probably safer to operate in most consumer environments than those that have not been certified by the UL.

Install smoke and carbon monoxide detectors in the heated space.  With any portable heater, given how easily they can be deployed, the risk of fire exists, whether from the space heater itself, or from close by items that it overheats.  Early warnings of such fires, that often begin as smoldering that can go for hours before open flames erupt, often save many lives.  Smoke, carbon, and fire detectors supply these advance alerts, allowing occupants to leave the area before fumes or flames consume them.  Detectors are essential to reducing the fatality dangers often associated with portable space heaters.

Always read manufacturer’s instructions before running the heater.  A heater is a heater is a heater.  But NOT always so!  Each space heater type has its own operational peculiarities, warnings, and best-use instructions.  The advice in this post is general in nature, and is typically useful for all heaters.  But it should not replace the manufacturer’s user’s guides and manuals.  Information in those guides should always supersede what you read here, though hopefully, they agree with us for the most part.

Position space heater well away from anything flammable.  Set up your heater far from drywall walls, curtains, furniture, beds, couches, love seats, play areas with toys that could catch fire, and electronic appliances that the heat could melt or otherwise damage.  Place heater at least three feet from any combustible materials.  Even non combustible items should be kept at least this distance away from the discharge side of the heater, so they do not interfere with proper heat radiation and / or convection.

Avoid fumy, damp, or dusty locations.  Of course, the heaters with flames burning inside can ignite flammable fumes with ease, as a match ignites dry straw.  But even the electric ones, with their arcing thermostats (most still use physical contacts to activate and deactivate the heating elements), can trigger explosions and fires in the presence of gasses and fumes.  Further, what may appear to be harmless dust can interfere with proper heater operation by accumulating on elements, generating fowl odors of burning.  Plus, it can ignite as well; particularly if enough of it has accumulated inside the heater.  So, not only is routine heater cleaning essential to safest operation, but keeping the space heater away from airborne dust in the first place is by far the best failure and explosion preventive step.

Keep heaters on the floor.  Avoid setting them on tables or other furniture.  Not only does this improve the comfort level by providing more uniform heat circulation in the room, but also reduces the chances that the heater will tip over and fall from higher places, damaging or igniting nearby items.

Always stand the heater flat on all its feet.  No leaning it backward on two legs or sitting it on a slope.  Avoid propping it backwards against a wall.    The only contact the space heater should have with other objects should be through its supporting feet.  So keep objects away from any of its other surfaces. Place it on a flat, level surface, and if it features locking casters, be sure to lock them once you’ve placed the heater.

Regularly maintain the heater.  Periodically clean it, inspect it, replace worn parts (burned wicks, frayed power cords, corroded plugs, clogged fins, Etc.), lubricate fans and other moving components, repair it, and replace it when you must.  We recommend performing these steps during the summer, prior to the next heating season, as maintenance tasks at this time allow ample time for obtaining replacement parts before autumn temperatures arrive.

Don’t ask a portable space heater to do a permanently installed heater’s work.  Space heaters are intended primarily for temporary and attended operation.  They’re small enough to easily carry around, require no specialized plumbing or wiring (usually), and are designed to heat average sized rooms, with average insulation, with average windows, to average comfort temperatures, with average temperature swings, during average cold weather months.  They may not work well in houses located in extremely cold climates, in rooms with many drafty windows, and places where getting fuel to them is exceedingly difficult.  In our experience, portable heaters did not produce enough BTUs in our home for best comfort.  So we decided to install permanent electric baseboard heaters which offered more heat output, quieter operation, and less loading of existing electrical circuits (we ran separate circuits to each of them).  Permanent heaters are typically mounted on or in walls or along baseboards, well away from traffic.  Plus, their wiring or piping does not run across the floor, and so, poses less of a tripping hazard.  If you must always rely on a portable space heater to adequately heat a space or require unattended heating, then we strongly recommend that you consider installing permanent space heaters.  They’re safer than portables, generally perform better over a wider range of outside temperatures, and have less parts to maintain and replace.


Guidance for Safest Electric Portable Space Heater Usage

Avoid extension cords.  The heaters come with intentionally short power cords to minimize tripping risks, maximize heater performance, and to prevent overheating of the cable.  Avoid defeating these purposes by not using extension cords and power strips where possible.  Plug them directly into the wall.  But if you MUST have an extension cord, then select the shortest UL approved cord possible, and one that can handle the heater’s maximum current value (typically fifteen amps for home electric space heaters).

Keep power cables uncoiled.  High current-carrying AC cables such as those on electric space heaters can overheat due to inductive reactance, and catch fire, as well as reduce heater performance, especially when heater is running at full power.  Check for cord as well as plug overheating periodically during operation.

Verify ground prong connection.  If your space heater features a three prong plug, then be certain that the third prong on the desired electrical outlet is   actually connected   to ground.  Beware that particularly in older houses and buildings, while the outlets themselves may have been upgraded from two to three prong sockets, often the wiring that feeds them has not, and the third prong hole is either left unconnected, or more dangerously, connected to the wrong side of the two-wire power line.  An inexpensive outlet tester can verify proper grounding.  If the outlet tests faulty, then either find a correctly functioning one to use, or get help from a qualified electrician to fix.

Keep plug prongs shiny.  Corroded or otherwise dull-looking or dark colored AC plug prongs create high resistance connections with mains electricity.  This can cause melting of the heater plug, the outlet into which it’s plugged in, and can create burn and electrical shock hazards.  So as part of your periodic heater maintenance, inspect the plug.  If its prongs are dark or dull, try polishing them clean with steel wool or brass cleaner.  Replace any melted or deformed plugs and outlets, or any power-handling components that show signs of overheating.

Protect heater cord from damage.  Do not route the power cord under rugs, tables where someone’s shoe might be snagged by it, or

Use dedicated circuits where possible.  Since electric space heaters typically draw fifteen to twenty amps, which approaches the maximum current load capacity of most 120 volt home branch circuits, avoid circuit overloads by running your heater on branch circuits with no other high-power devices plugged into them.  For example, avoid powering your hair dryer from the same circuit as your electric space heater.

Heat dry locations only.  Keep electric space heaters away from water and dampness, to reduce risks of electrocution and premature failure of internal components.

Combustion Space Heater Safe Operation Tips, Advice

Use only approved fuel holding tanks, bottles, and containers.  Official kerosene cans and tanks are typically blue or gray in color and display the word “Kerosene” embossed on them.  Do not transport kerosene fuel in a gasoline can, especially if that can has carried gasoline previously.

Ideally, Fill heater outdoors.  To minimize fuel fumes inside your home, carry your space heaters outside for refueling.  So choose lighter heaters — ones that are not so light that they’ll easily tip over, but still light enough for frequent carrying with ease.

Operate only in well-ventilated areas. Any combustion based portable space heater produces some exhaust, simply due to the burning of liquid or gas fuels.  Operating these in areas without much ventilation (too air tight), can create a build-up of noxious gasses, as well as depletion of oxygen in the area.  These situations can create health problems (or worse) for people spending too much time in said areas.

Do not use propane garage heaters indoors.  These radiant style heaters, often fitted atop propane gas tanks, feature a plaque that becomes bright red hot during operation, is surrounded by a large blue flame, and create a “heat beam” that can melt and combust objects in its path up to as much as three feet away.  Plus, they often have no ODS (oxygen depletion sensors).

Do not place any combustion heater in bedrooms.  They can fill the room with carbon monoxide or deplete its oxygen supply, undenounced to people sleeping there.

Position away from high foot traffic areas.  While space heaters work best when centrally located within a room, do not place them in the middle of the floor if people often walk around there.  You may have to sacrifice some heater efficiency to get improved people safety.  But you’ll still see decent performance if you select a heater that’s designed to operate with its back close to a wall, that radiates its heat into the room center.

Wait several minutes after filling to light.  Allow the fuel fumes to dissipate before starting the heater.  Failure to do so can trigger explosions and cause bodily harm.  Do not strike as long as you still smell fuel in the area.  If you smell it, don’t light it.

If heater shuts off, wait for it to cool before attempting a restart.  Doing so reduces the risk of you burning yourself on hot heater parts, and allows any thermal protective systems inside the space heater to reset.


Portable space heating is an essential methodology in today’s America, and used wisely, can be just as safe as furnace-based central heating.  We hope that the advice and tips here help you use your space heaters wisely, achieve maximum comfort from them, and avoid their pitfalls and dangers.   You don’t want to be ignorant of the ways of safely heating your space; it could become a question of life and death.  Happy heating!

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Revision History

  • 2015-10-22: Added appropriate tags.
  • 2015-08-20: Originally published.