During cold weather, many folks use eclectic space heaters to keep comfortable. One of the most frequently asked questions I get is from folks wanting to know how much their space heater will cost on their electric bill.
Most household electric space heaters in the North America are rated for either 750 Watts or 1,500 Watts. Many of the 1,500-Watt size space heaters have two power settings. High for 1,500 Watts and Low for 750 Watts.
Why is 1,500 Watts the maximum?
A single 1,500-Watt electric appliance is the most you can use on a single circuit in residential housing. If you plugged in anything more powerful, you will blow a fuse or pop a circuit breaker.
In fact, you can only use two or three plug in electric space heater in a typical house because of the limited number of circuits. If you use your hair drier or electric fry pan on the same circuit as an electric space heater, you will knock the power off for that circuit.
Do not be frustrated by this. Remember electric circuit over load protection is there to prevent house fires.
It does not mater if the heating element is a heating coil, a light bulb, or any other device. Plug in space heaters are all made to use 1,500 watts or less.
They are all about 100% efficient so efficiency claims do not matter
Since 1,500 watts is the power input limit, the heat out put limit is about 5,000 BTU (British Thermal Units) per hour. All of the different heating elements are about 100% efficient.
An old fashion light bulb is only about 90% efficient as a heater. However, after the 10% that is light energy bounces around through the air it too becomes heat. Fan motors are only about 80% efficient but the energy wasted is in the form of heat, so it is not wasted when you want heat.
How do I estimate how much my space heater will cost to run?
To figure out how much money your space heater will cost you need to know what you will be paying for your next kilowatt-hour of electrical power. Not easy because the price is different for every utility company in North America.
Check your bill. It may say right on it what your cost of a kilowatt-hour (kWh) is. My home electric bill gives me very limited information, but it says the electric rate is 6.42 cents per kWh.
That number is not the whole story. It does not include taxes, the customer charge, distribution charges or cost recovery charges.
They way to get a good estimate of your cost per kWh is to divide the total dollar amount of the bill by the total number of kilowatts that they are charging you for. On my last bill I was charged $87.47 for 741 kWh used. That divides out to 11.8 cents per kWh.
Rounding that to 12 cents per kWh and looking at the chart above it would cost me about 18 cents per hour to run one space heater. Doesn’t sound too bad for the comfort it gives.
If I used that space heater 10 hours a day the cost per day would be about $1.80. Most of the time there are 30 days in a month, so at most one space heater running 10 hours a day would add $54 to the electric bill. Since my total bill from just after thanksgiving to just before new years was $87, you can tell we do not use a space heater very much.
Actually, my wife uses one for about an hour in the bathroom to boost the temperature while she takes her shower, but only on very cold mornings. I dare not complain.
The $54 a month is most it would be. If the thermostat on the space heater is set right and working, it should not be heating all the time. It should be cycling on and off. It should heat the room, shut off, and then wait while the room cools, and then heat again.
It may be on only 60 or 70% of the time. That means the monthly cost might be more like $35. Reducing the time that you use the heater will reduce the cost.
Folks who live in parts of the country where the electric prices are higher will pay more. Check the chart for how much per hour.
A $250 electric space heater rated for 1,500 Watts and a $20 space heater rated for 1,500 Watts both cost the same on the electric bill and both produce the same amount of heat. One looks like a piece of furniture and the other looks like a space heater. Choose wisely.