WATLOW Over-the-Side Heaters

Watlow’s immersion heaters are designed primarily for direct immersion in liquids such as water, oils, solvents and process solutions, molten materials as well as air and gases. By generating all the heat within the liquid or process, these heaters are virtually 100 percent energy efficient. These versatile heaters can also be formed and shaped into various geometries for radiant heating and contact surface heating applications. UL® and CSA component recognized elements are available.

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Product Description

Product Description

Over-the-side heaters are ideal for heating water, oils, solvents, salts and acids. Over-the-side heater application versatility is enhanced with optional sheath materials, kilowatt ratings, terminal enclosures and mounting methods.

The L and O shaped “installed-from-the-top” heaters slide easily into tanks, with the heated portion immersed along the side or at the bottom. The drum immersion heaters are designed for direct immersion in a standard 55 gallon steel drum. Watlow® vertical loop immersion heaters are well-suited for open tank applications.



Material Maximum Operating Temperatures Maximum Watt Densities
°F °C W/in2 W/cm2
Alloy 800 1600 870 60 9.3
N/A 1400 760 43 6.7
N/A 750 400 23 3.6
N/A 1200 650 60 9.3
  • Alloy 800 sheath element watt densities to 60 W/in² (9.3 W/cm²)
  • Wattages to 50 killowatts
  • Voltages to 600VAC
  • Applications


  • Water heating
  • Freeze protection
  • Viscous oils
  • Storage tanks
  • Degreasing tanks
  • Solvents
  • Salts
  • Caustic solutions
  • Paraffin
  • Features & Benefits

    Features & Benefits

    Features Benefits
    Rugged, light-weight construction
  • Resists damage during installation or removal
  • 0.475 in. (12 mm) diameter WATROD heating elements
  • Offers one- or three-phase operation
  • WATROD hairpins are repressed (recompacted)
  • Maintains MgO density, dielectric strength, heat transfer and heater life
  • Four inch (100 mm) sludge legs
  • Keeps heating elements off the tank’s bottom to help avoid being covered with sediment
  • RTV riser seal
  • Prevents moisture from infiltrating electrical areas
  • SRG insulated flexible lead wires, rated to 390°F (200°C)
  • Allows factory or field wiring for three- or one-phase operation
  • Riser materials are compatible with element sheath materials such as stainless steel with Incoloy® sheath and steel with steel sheath
  • Meets varying application needs
  • Ensures ease of use
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