There should be a label on the heater designating how many watts it uses. Assuming the following: P = power in watts, E = potential in volts, and I = current in amperes, use the following formula:
P = I times E. Example if the voltage is 120 Volts and the power in watts is 500, then the current would be 4.17 amps.
or, if this is a 12 Volt unit, then current would be 41.7 amps.
In the first example, if the electric rate is 15 cents per kilowatt hour, your electicity cost would be 7 1/2 cents for every hour you run it.
