STS Thermal SystemsSTS Thermal Systems
STS Thermal Systems

Over-The-Side-Immersion Heaters

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Download Tank Heater Application Worksheet

Over the side immersion heater offers a wide variety of styles and shapes to meet nearly all needs. Whether you are heating a small pail of water or a large tank of caustic, we have the right product for the job. If standard designs do not match the application, we offer fast delivery on most custom designs. Since direct immersion is 100% efficient and over the side immersion heaters require no tank modification these are the most easily used yet among the most effective means to heat your process. Used in tanks where through-the-wall heaters cannot be installed, portability is required, or where heaters must be removed for cleaning without emptying the tank. Suitable for freeze protection, for heating viscous materials to improve flow, or most open tank applications with proper sheath and watt density selection.


  • Lightweight and portable
  • Self supporting
  • All compatible materials
  • Stainless steel elements; stainless steel riser
    and junction box
  • Incoloy elements; stainless steel riser and junction box
  • Steel elements; steel riser and junction box
  • Watertight terminal housing with terminal block
    for wiring
  • Thermowell for installation of thermostat
  • Sludge legs
  • .430" diameter elements

Over The Side Imm


Over The Side

Depending upon sheath material and watt density considerations, Immersion Heaters can be used to heat many various solutions.

  • Easily installed or removed for cleaning, inspection or moved to improve heat distribution
  • Narrow profile to allow maximum work space in tank
  • Moisture explosion resistant terminal enclosure
  • Optional cord and plug
  • Specify passivation or other external finishing if required


  • Built-in thermostat: 0-100°F, 60-250°F, 50-250°C or 150-550°F
  • Explosion Proof or Moisture Proof enclosures
  • Passivated on wetted surfaces
  • Built in contactors and control transformers
  • Special sizes and ratings
  • Special materials of construction
  • Thermocouple for process control or high limit
  • Various riser pipe heights

Over The Side -Formed Element- Tank Side (SOS) Series

For industrial water heating and many other aqueous solutions which are generally "clear" and also compatible with both steel and Incoloy.


  • Incoloy® 840 sheath
  • Moisture tight PVC housing
  • Stainless Steel bulkhead fittings
  • Compact, low cost
  • Stainless Steel hanging bracket
  • UL & CSA Recognition on elements




Over The Side -Staight Elements- Tank Bottom (OL) Series


  • PVC NEMA 4 housing
  • ½” thermowell for optional thermostat
  • 4″ sludge legs below elements
  • All welded & pressure tested construction
  • Moisture sealed riser pipe to avoid condensation
  • Recompacted bends in heaters


OTS OL Series

Over The Side -Curved Elements- Tank Bottom (OR) Series


  • PVC NEMA 4 housing
  • ½" thermowell for optional thermostat
  • 4" sludge legs below elements
  • All welded & pressure tested construction
  • Moisture sealed riser pipe to avoid condensation

OTS OR Series

Over The Side -Vertical Loop (VO) Series


  • Moisture proof terminal enclosure
  • Simple installation
  • Maximum working space in tank due to thin profile


Oils, water, mild corrosives

VO Series

VO Side view

OTS Immersion Heaters