Over-the-side or OTS heaters as they are commonly referred to are used in two principle applications. The first is where installing a heater through the sidewall of the tank or vessel is not viable (because of material or special constraints) and the second necessitates the frequent removal of the heater. The key advantage of the Over the side heater is that the tank does not have to be drained in order to remove the heater for maintenance or servicing.

Over the side heaters are configured principally in two designs; the first is installed vertically in the tank, close to a sidewall. These types of applications normally do not have liquid level variations. It is important to note that the heated section of the elements always remain submerged. The second design type involves an L-shape with the heating elements arrayed horizontally, either straight out or in a curve, following the curvature of the tank wall. This style of heater is used when there are fluctuations in liquid level and by design, the heated portion of the tubular elements are located in the lower part of the tank, allowing them to remain submerged as the liquid level fluctuates. Depending on the vertical height requirements of the application, the OVER THE SIDE L-shape can be comprised of any length vertical riser, a two-inch pipe, welded to an element terminal box, where the elements are arrayed horizontally. On shorter verticals, the vertical section can be made of the tubular element, with a specific cold section. Thermowells are available as are feet and brackets to support the element arrays.

NEMA 4 (moisture resistant) enclosures are standard on all OVER THE SIDE style heaters and NEMA 7 (explosion proof) is available. Regular thermostats or pilot duty thermostats can also be fitted within the terminal enclosure.