Circulation heaters are used primarily to heat moving, flowing, or circulating fluid streams.  Fluid flows through the heater, which transfers heat to the stream.  Any liquid or gas is generally acceptable for use with a circulation heater. Often, circulation heaters are used as stock tank heaters, asphalt heaters, livestock tank heaters, circulation tank heaters, dry well heaters, and septic tank heaters. 

Important parameters to consider when specifying circulation heaters are maximum operating or sheath temperature, AC voltage required, AC voltage phase, watts and watt density. Maximum operating temperature is the maximum temperature that the sheath covering the circulation heater may reach. The maximum sheath temperature does not represent the maximum temperature that a heated substance may reach. AC voltage required represents the minimum alternating current (AC) volts required to operate the heater. AC voltage phase can be either single-phase or three-phase. Watts represents the maximum wattage available from the circulation heater. Watt density is the amount of wattage, per square inch, that the circulation heater is capable of delivering. Watt density is calculated by dividing the available wattage by the heated area. Watt density is a good measure of the heater's ability to quickly heat a substance. High watt density heaters should not be used with extremely viscous materials, materials that are poorly circulated or explosive/volatile materials. Important dimensions for circulation heaters include heater height, inlet and outlet separation, diameter and nominal pipe diameter, both inlet and outlet.  A circulation heater will generally have identical inlet and outlet diameters.

Circulation heaters may have one of several types of connections. These include flanges and NPT pipe threads.  A heater may be available with multiple connection types. A sheath, sleeve or jacket is the protective covering for the heater.  Some circulation heaters may be available with multiple options for sheath material.  The sheath material for circulation heaters can be one of many types including, iron, stainless steel, and steel.  A circulation heater may be mounted or installed into a stream using multiple methods.  Mounting types include ANSI flange and screw (NPT) plug. Features common to circulation heaters include adjustable thermostats, sanitary application approval, cooling option, corrosion resistant, cryogenic use, custom heater design, explosion proof housing, integrated thermostat, and UL approved.