Electric heaters have been around for decades as a source of heat in homes to provide warmth to us. One of the reason for their popularity is because of lower cost to purchase and easy maintenance compared to other sources of heat. They are usually powered by electricity though a small percentage are still using propane or kerosene as fuel.
They work by converting electricity into heat using metals as heating elements. The metals have high resistance that permit a certain amount of current to flow through them to provide the required heat. Electrical energy is changed into heat energy and the relationship between the wattage and Btu/hr. is: