Radiant flat panel heaters are used to heat objects via radiant heat transfer, usually via infrared (IR) waves. They are used in a variety of industries and applications, including: space heating, drying, curing, water evaporation, food processing, material preparation, bonding, joining, and industrial processing. Power requirements for radiant flat panel heaters include maximum operating (sheath) temperature, phase, alternating current (AC) voltage, heating capacity, and watt density. Maximum operating (sheath) temperature is the highest temperature that the heater's sheath or sleeve may reach. Note that this is not the maximum temperature that a heated substance may reach. Some radiant flat panel heaters use single-phase power. Others use three-phase power. Heating capacity is the wattage which a radiant flat panel heater can deliver. Watt density is a good measure of how quickly radiant heater can transfer heat to a surface. To calculate watt density, suppliers divide the available wattage by the heated surface area.