Several years ago I began to see ads for electric heaters that were reported to have found some new technique to provide electric heat in a way that was suggested to help you reduce your home heating bills by up to 50%. I am a fan of using electric for both heating and cooling since this eliminates the need to have fossil fuels burning in the home, so I took a special interest in finding out if these claims could be true.
"We have all seen the ads to cut heating bills in half with a $400 to $600 space-age electric heater. Some even sport a 'free' fireplace hand-crafted by the Amish. Are these deals too good to be true?"
The answer to the practicality of money saving electric heaters as compared to less expensive electric heaters turned out to be rather simple, yet, to share this answer requires that you have some background information so that you understand why the answer is what it is, in lieu of simply taking my word for it. The calculations used in the coming paragraphs are not complicated, but it may be helpful to read the article a second time to fully see how and why the answer is what it is.
To start, when looking to evaluate anything, you must have something concrete on which to base your assessment. When it comes to using electricity, that it quite simple. We refer to OHM's Law and the formula P=ExI which translates as WATTS = VOLTAGE x CURRENT, which more simply means, the electric power you get out of something is based upon the voltage applied and the amperage used.
For example, standard baseboard electric heaters that run on 240 volts generally provide 250 watts per foot of heat. A typical 6 foot electric heater would then provide 1500 watts (6 x 250 = 1500 watts) of heat. To provide this amount of heat, the unit must use current or amperage accordingly. In our case, the current can be found with the formula I=P/E or CURRENT = WATTS divided by VOLTAGE, which equates to 6.25 amps = 1500 watts divided by 240 volts.
Likewise, a standard electric space heater that runs on 120 volts typically provides an output of 1500 watts of heat. To provide this amount of wattage, the unit must consume double the current or amperage since the voltage is half. Again, the current can be found with the formula I=P/E or CURRENT = WATTS divided by VOLTAGE, which equates to 12.5 amps = 1500 watts divided by 120 volts.
As you can see, by using either 120 volt or 240 volt heaters, you obtain the same output watts of heat due to different amounts of current being used. Since your power utility company charges you for watts, it doesn't matter whether you use 120v or 240v to provide your 1500 watts of heat. It's all the same to them. If your utility company charges 14 cents per kilowatt hour, this means you pay 14 cents for every hour where you consume 1000 watts or 1KW. If you used the 1500 watt (1.5 KW) heater for one hour, that is equal to 1.5 KW x .14 = 21 cents per hour.
Next, let's formulate the room size this 1500 watts can heat. The worlds accepted heating unit is called the BTU or British Thermal Unit. When determining the BTU's provided by any electrical heating source, simply multiply the watts by 3.413 and the resulting number is the BTU's. In our case 1500 watts x 3.413 = 5119 BTU's. Most manufacturers of 1500 watt heaters generally say they provide 5120 BTUH's or British Thermal Units per Hour.
Now, the colder your average climate, the greater your heating needs will be. Because of this, there is no set level of how many BTU's are needed to heat your room. For example, if you live in Montana, winter temperatures can easily stay in the teens or single digits for days on end. You would need sufficient heat to add 50 to 60 degrees of heat to the air to maintain a 65 to 70 degree room temperature. Alternatively, if you live in Georgia, winter temperatures can easily stay in the thirties or forties most days. You would need sufficient heat to add only 30 to 40 degrees of heat to the air to maintain a 65 to 70 degree room temperature.
In our example, you would require twice as much heat in Montana than in Georgia, which means a 1500 watt heater in Montana will only take care of a room half the size it does in Georgia. To resolve issues with temperature differences, we'll introduce a temperature zone multiplier of 40 for cold climates, 25 for moderate climates and 10 for warmer climates. Add another 10 if the house is not insulated well and add another 10 if the windows and doors do not seal well.
To begin calculating the BTU's required for a room, you first need to obtain its square footage by multiplying the rooms length by its width. A ceiling height of 8 feet is assumed. To compensate for taller ceilings, increase the square footage by 12% for each additional foot of ceiling height. For example, a 12 x 12 room is equal to 144 square feet. If the ceiling height were 9 feet we would multiply 144 x 1.12 for a total of 161 square feet.
Now, depending upon your temperature zone, multiply your square footage by your temperature zone multiplier. Using our example, if we were living in Montana, we would multiply 144 square feet x 40 for a total requirement of 5760 BTUH's for that room. This is just short of the 5120 BTU provided by a 1500 watt electric heater, but it should suffice in most instances. If the house were not insulated well and had issues with air infiltration, a larger or second heater would be required.
Meanwhile, any claim by an electric heater manufacturer that says their heater will heat 300 square feet or 1000 square feet means nothing if there is no reference to the outside temperature or condition of the room. The newest version of the money saving electric heater claims to be able to heat 1000 square feet, but it uses only 1483 watts. Our previous example shows how this could be marginal even for a 144 square foot room, let alone 1000 square feet. Using our same example, a 1000 square foot room at 40 BTUH per square foot would require approx 40,000 BTU of heat. To determine the watts, we divide that by 3.413 to get 11719 watts, which is almost eight times greater in size than the wattage provided by the money saving heater.
We do have to be fair and determine the conditions under which the 1483 watt heater could heat a 1000 square foot room. Bear in mind, this is equivalent to a 14 ft x 72 ft space, or an entire modular home. Let's work backwards to find the temperature zone where this might work. 1483 watts x 3.413 = 5061 BTU. We divide this by 1000 square feet to obtain a temperature zone multiplier of 5. Remember, a temperature zone multiplier of 40 is for a cold climate, 25 is for a moderate climate and 10 is for a warm climate. Basically, a temperature zone multiplier of 5 means you could heat 1000 square feet of space in Florida during the winter.
OK, so now we know how and why a 1500 watt electric heater will heat an average room size of 12 x 12 by providing 5120 BTU's of heat energy using approx 6.25 amps while plugged into a 120 volt outlet.
If your $400 to $600 heater says it provides 1500 watts, it will do absolutely nothing different than what a $60 heater can do by providing the same 1500 watts. If you set either heater in the room that also includes the thermostat for your whole house heating system, you will reduce your houses overall fuel consumption because the thermostat will not sense the need to activate the heating system. This can save money, but the remaining rooms in your home could get very cold and possibly result in freezing damage.
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Just for the fun of it, let's say we ran a $60 1500 watt electric heater 16 hours a day, for 4 months straight, what would this cost? 16 hours x 7 days x 4.25 weeks per month x 4 months = 1904 hours x 1.5 KW per hour = 2856 KWH. At 14 cents per KWH, the total cost for power would be $400 plus another $60 for the heater for a total of $460 in all.
Now, let's say we ran a $500 1500 watt electric heater 16 hours a day, for 4 months straight, what would this cost? 16 hours x 7 days x 4.25 weeks per month x 4 months = 1904 hours x 1.5 KW per hour = 2856 KWH. At 14 cents per KWH, your total cost for power would be $400 plus another $500 for the heater for a total of $900 in all.
Imagine a drumroll. Here's the simple answer...
If you take the $900 spent to heat a room with a money saving heater and then minus the $460 you really only needed to spend by using a standard heater, you were overcharged by $440 which you have unknowingly donated to Amish farmers or to Bob and his sponsors. Don't get me wrong, making donations is an American tradition and is depended upon by those in need, but I believe that if you are going to make this donation, you should at least know it's a donation. With this information in hand, you could better determine for yourself if a companies need for profit is greater than your need to keep your family fed and warm this winter.
What Else Could You Do With $440.00 Dollars?
If you choose to purchase a standard $60 ceramic electric heater ( very safe, reliable and comfortable ) in lieu of a money saving electric heater, what could you do with all the money you saved?
- Buy 170 gallons of fuel oil at $2.60 per gallon and heat your house completely for 30 days
- Buy 21890 cu ft of natural gas at $2.01 per ccf and heat your house completely for 30 days
- Buy 3 tons of coal at $146 per ton and heat your entire house for 3 months
- Buy a second $60 1500 watt heater and heat an entire other room for 4 months
- Hire a company to insulate and weatherize your home, saving 15% to 25% on all heating and cooling costs for years to come
- Buy groceries for a family of 4 for 2.5 weeks
- Contact Feed the Children and make a real donation that provides food and essentials for 9 starving children for 5 months
Electricity is already the most efficient method of heating, since it is 100% efficient. By combing electricity with heat pump technology, you could extract heat from the ground or air and use electricity to gather heat from these other sources, but the electricity itself cannot morph into more than what it is. There is no magic way to make pure electrical power provide more watts than the laws of physics allow.
For now, the best thing you can do to save energy is to spend your money on insulating and sealing your home so that the energy you do consume is used more effectively. A couple hundred dollars spent on home weatherization can save thousands of dollars as the years pass, regardless of what method you use to heat and cool your home. Be smart, be green and conserve what you are already using and you'll save more energy and money than any money saving heater company can ever hope to convince you of otherwise.
David's career highlights include authoring 'The Rewards of Making Energy-Efficient Choices', working in the electrical engineering division of three nuclear power plants and serving as an administrator, engineer and installer in the heating and air conditioning field.
He lives in Northeast Pennsylvania with his wonderful and supportive wife, Karlene and spends his time writing and performing home energy audits.