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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


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

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
Standardized size 1 in. (25 mm) conduit openings
  • Facilitates wiring
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