Inline Heaters

Inline heaters (a.k.a. circulation heaters) are ideal for processing fluid, including hazardous liquids, that requires intermediate heating while maintaining a flow rate. Instead of stripping the heat from another source as it would for a heat exchanger, an inline heater simply transfers the heat generated from electrical power into the target fluid.

Composition of inline heaters

Inline heaters comprise heating elements covered by an anti-corrosion metallic vessel chamber. To maximize efficiency, the flanged heater is often thermally insulated by either the side or inline operation. This is particularly done when a flowing medium has to be heated.

A pump unit transports the inlet fluid into the circulation system. The fluid is then continuously circulated and reheated in a closed loop around the immersion heater until the desired temperature (up to 1000°F) is reached. The heating medium will then flow out of the outlet nozzle at a fixed flow rate determined by the temperature control mechanism.

Different applications call for varying options for terminal enclosure, sheath material, flanged connections, and temperature ranges. Several mounting options are also available such as integral mounting utilizing SCRs and remote mounting which uses contactor control panels.

Vessel heaters are a type of inline heater manufactured as a packaged unit containing several components such as heating element, chamber, thermostat, sensors, insulated material, brackets for mounting, and electrical connections. The efficiency of this heater is high as all heat is produced within the substance or vessel. The operation is fast and executed in a short time. The heat generated is evenly distributed throughout the substance. The main characteristics of inline heaters are efficient heat transfer, ease of installation and maintenance, and compatibility with the current standard industrial piping. Applications such as waste oil, steam and water processing can use inline heaters to regulate and control the temperature, but also to maintain fluid viscosity. Improper liquid viscosity could gradually slow down overall production processing time. In addition, a slight deviation in viscosity could affect the product's final yield and purity. To avoid this type of problem, an inline heater can heat the fluid so that at the temperature the viscosity remains unchanged and the fluid proceeds at a desirable flow rate. To control the liquid flow rate, the heater's wattage can be manipulated and regulated to obtain the desired temperature. In other words, the flow rate is directly proportional to the temperature/liquid viscosity.


Almost all inline heaters use thermocouple sensors that can be integrated with any control to manage the temperature range. Tools such as the RTDs and digital thermocouples can be used to precisely control the temperature of the heating system. For extra protection, optional components such as moisture resistant or explosion proof housing are available for special applications. Drain valves are also available on the circulation heater to facilitate system maintenance, whereby the leftover fluid or residues (such as water or calcium) can be easily removed from the equipment. Special mounting options are available for the target application's mobility requirement. On WATTCO units, the flange immersion heater inside the circulation unit can be customized depending on the chemical and physical properties of the target fluid. Other customization options, such as the equipment orientation (vertical or horizontal) or flange type, are also available.

There is a wide variety of immersion heaters on the market, which can be tailored to meet specific needs of an oil plant. The offered products can be used in a variety of applications that feature high pressure ranges or are executed in hazardous regions.

Many applications make use of industrial heaters. The most common of these are heating oils, corrosive solutions, water cooled engines, oil sump heaters, process kettles, blending mills, moulding dies, steam superheating and preheating purposes such as viscosity pumping and oil delivery to burners.

Ilan Toledano, is the President of Wattco. With over 20 years of experience in the electric heating industry, Ilan Toledano has been involved in sales and marketing, product development, and expansion of the industrial immersion heaters in the chemical and oil and gas industry for the past 15 years. Mr. Toledano has a B.Comm from Concordia University in Finance and Business Law; 

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