Principals of Electric Resistance Heating:
In electric resistance heating, metals are generally used as heating elements. These metals are designed to permit a certain current to flow to provide the required heat. (This may be either 120 V or 240 V)
Some units are designed to operate at incandescent or glowing temperatures. Some units are mounted in protected cabinets. The systems that do not glow are known as non-incandescent temperature units.
The higher the heating element temperature, the smaller the space it must occupy. Some units are designed with high temperature heating elements. They release both air (convection) heating energy and radiant energy. Electrical energy is changed into heat energy in the following ratios:
1 watt = 3.415 Btu / hr
100 watts = 341.5 Btu / hr
1000 watts = 3415 Btu / hr
The voltage multiplied by the amperage flow in a circuit equals the wattage.