Learning About Space Heaters

A cold blue norther could blow in at any time, bringing chilly weather with it. We know it’s coming sooner or later. Portable space heaters are great for supplementing central heating or to help heat a small room. If you use them, make sure you do so safely. Here are some tips from the National Fire Protection Association to make sure you stay warm safely this holiday season.

Heater Checklist

  • Make sure the heater you buy has the seal of a qualified testing laboratory (such as Underwriters Labs - UL.)
  • Keep the heater at least 3 ft. away from anything that can burn, including people (and pets).
  • Choose a heater with a thermostat and overheat protection.
  • Place the heater on a solid, flat surface.
  • Make sure your heater has an auto shut-off to turn the heater off if it tips over.
  • Keep space heaters out of the way of foot traffic, and never block an exit.
  • Plug the heater directly into the wall outlet. Never use extension cords.
  • Space heaters should be turned off and unplugged when you leave the room or go to bed.


Which is the most efficient space heater? Frankly, read ten different sources, and that’s about how many different answers you will get. However, according to Energy.gov, electric convection (non-radiant) space heaters, may provide a slight advantage. The best types incorporate a heat transfer liquid, such as oil, that is heated by the electric element. The heat transfer fluid provides some heat storage, allowing the heater to cycle less and to provide a more constant heat source. To read more about the types of space heaters, go to the Department of Energy website.

How much will a space heater increase my bill? If you utilize an electric space heater this winter, remember that some models use a considerable amount of electric energy. To weigh the advantages and disadvantages of using a space heater, it’s important to know what size you need for the space to be heated. Find a space heater rated for the approximate square-footage or size of the room where you will be using it. Using a heater that’s too small for your room causes it to work overtime to warm your space, which wastes energy and could increase your energy bill.

The formula for determining how much heating power you need would be: Total Square Footage times 10 = Total Wattage. (If you have poor insulation, use 12 watts in the equation, instead of 10.) This assumes you have a standard 8 foot ceiling.

Heaters for small spaces are usually less than 1,000 watts. Those for standard/medium size rooms are up to about 1,800 watts, and those with more than 1,800 watts are for very large spaces.

To calculate the approximate cost to operate the space heater, figure the time the heater will be in operation, in hours. Next, convert the kilowatts used per hour. To do this, take the maximum wattage of the heater and divide it by 1,000.

RGEC’s Regular Texas Residential Rate, Tariff #202.1, is $0.1203 (add the Power Cost Adjustment per kilowatt-hour (kWh), which for October was $0.00050) for a total of $0.1208. Use this in your formula for a close approximation.

Example: $0.1208/kWh times 6 hours times 1.5 kWh per hour (if it is a 1,500 watt heater) = $1.08 per day.

Multiply $1.08 per day by 30 days (month) to get the approximate additional amount you can expect to see reflected in your electric bill due to the heater. In this example, the total would be $32.40

Remember that there may be other factors contributing to your electric bill this time of year, such as extra cooking and Christmas lighting.