An 8,000-gal rectangular aboveground storage tank filled with diesel fuel was installed at a major airport in the Chicago area. With a winter temperature of ‐20°F (-7°C), a heater is required to maintain the fuel at 40°F (4°C), a temperature that maintains free-flowing viscosity.

Because openings are not allowed in the side of the tank, the only access for the heater was through the top. Using its I‐Heat heater selection program, heater maker Indeeco determined that a 2 KW immersion heater would do the job.

St. Louis-based Indeeco recommended an over-the-side flanged deep tank immersion heater with a remote industrial control panel. The heater used a 3", 150 lb, carbon steel flange and 0.475" dia steel elements rated at 6 W/in2. The 46" heating elements were mounted to a 76" riser, which positioned the elements in the lower half of the tank. The heater was furnished with both high limit and temperature control thermocouples. One of Indeeco’s standard NEMA 4X industrial control panels — equipped with a main power disconnect switch, controlling contactor, transformer, digital thermostat, Type J thermocouple controller, status pilot light and 150 W enclosure heater — was selected to control the heater.