Monday, January 25, 2010

Will space heaters really save money on your heating bill?

By David Burton
University of Missouri Extension

When winter weather begins and temperatures drop, many people start looking for ways to shave a few dollars off their heating costs.

According to Bob Schultheis, a natural resource engineering specialist with University of Missouri Extension, anyone planning to buy a space heater should carefully examine the claims manufacturers make about their products.

Portable box-style infrared electric heaters are being promoted heavily in stores, magazines and on television. Schultheis offers his analysis of some of the manufacturers’ claims about these heaters and heating systems.

Claim: Space heaters can slash heating bills up to 50 percent.

Reality: This is possible under certain conditions. “If you turn the thermostat in your house down and only use the space heater to heat the room you are in, you can lower your heating costs drastically. By turning the thermostat down by 20 degrees when outside temperatures are above freezing, you can reduce heating costs by up to 50 percent,” said Schultheis.

There are problems when a user moves to a different room. It is hard to take a space heater from room to room and keep all the occupants in the home in the same room. “You need to be careful how much you turn down the heat to the rest of the home. The result can be frozen pipes or excessive condensation forming on walls and ceilings, which could easily negate any energy savings,” said Schultheis.

Claim: Heat up to 1,000 square feet for pennies a day.

Reality: A well-insulated, 1,500 square foot home will require at least a 70,000 BTU per hour heating system to heat the whole house. These infrared heaters typically operate on 110 volts and use 1,585 watts of power at maximum output. One watt is equal to 3.413 BTUs per hour, so 1585 watts is equal to 5410 BTUs per hour. One infrared heater, therefore, will heat roughly one-thirteenth of the home.

If electricity costs $.08 per kilowatt-hour and the heater runs six hours per day, it will cost (1.585 x $0.08 x 6) or 76 cents per day. A geothermal heat pump could heat the whole house for that amount of money. From a safety standpoint, a 1,585-watt heater will draw over 14 amps of current, and so it needs to be on a separate electrical circuit from other loads.

Claim: A space heater doesn’t remove oxygen or humidity from the air and is 100 percent efficient.

Reality: “This is true. But, in fact, no electric or sealed combustion-heating system removes humidity from the air. Oxygen levels also are not affected by any electric or vented combustion heating source. All electric space heaters, whether they cost $40 or $400, are 100 percent efficient,” said Schultheis.

Claim: Provides even heat wall to wall and floor to ceiling.

Reality: Any convective heat source would do this naturally by convection currents or by using a fan. According to Schultheis, most space heaters are on the floor, so they heat the molecules closest to the floor first. These molecules rise in the normal convective process because this air now is less dense. It replaces the colder, denser molecules near the ceiling and eventually the room is heated evenly. This is not unique to any particular type of heater.

Claim: Does not emit poisonous carbon monoxide or harmful radiation.

Reality: Electric space heaters of any type do not emit carbon monoxide or other pollutants into the house. Unvented combustion space heaters do emit numerous dangerous pollutants and should not be used in confined spaces.

“While the advertising claims made for these infrared heaters are mostly true, they make the system seem like a revolutionary advancement in home heating. You can get similar benefits from a good quality space heater for much less than $300-$400,” said Schultheis.

“You’re not actually saving any money until you have recaptured the money you spent for the heater,” said Schultheis. “If they have the same wattage, a $40 heater pays back a lot quicker than a $400 heater, and they’re both putting out the same amount of heat.”

For more information on energy conservation, visit the nearest University of Missouri Extension Center, go online to, or contact Schultheis at the Webster County Extension Center in Marshfield at (417) 859-2044.

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