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Preferred Utilities

Preferred Utilities engineers and fabricates fuel oil handling systems for diesel generators and dual-fuel fired boilers for mission critical facilities such as data centers, hospitals, and emergency response facilities. Our engineers specialize in mission critical fuel oil system design so they are current with the latest industry practices and fire protection codes. In addition, Preferred Utilities offers a wide variety of fuel oil system components designed to meet the unique requirements of our fuel oil customers. Preferred Utilities' industrial factory is located in Danbury, CT

Suction Stub Heater

The Model SS Suction Stub Heater is specifically designed to maintain residual fuel oil in the tank suction stub at a pump able temperature during the time the oil is not flowing.


The Model SS Suction Stub Heater is a low watt density, thermostatically-controlled, electric immersion type fuel oil heater specifically designed to maintain residual fuel oil in the tank suction stub at a pumpable temperature during times the oil is not flowing.

Care should be used in selecting heaters for installation in the suction line to avoid oversizing or a subsequent high watt density applied to the heater surface. These conditions will cause temperature overrides which in turn lead to vapor lock at the oil pump. The wattage on the Model SS heater is relatively low, but is adequate to maintain the oil in the safe range of 80° F to 120° F during shutdown.

As shown in the sketch below, the heater is installed through the straight run of a tee located at the top of the suction stub. It is suitable for installation in 2″ or larger suction lines. The length “A” shown in the table should exceed the tank diameter by six inches because of the required pipe fittings. The thermostat settings and all wiring connections are located in a heavy-duty cast iron, water and vapor-proof electrical junction box. A contactor is not required.

The Preferred Model SS Suction Stub Heater is stocked for 230/208 VAC single phase current in a variety of sizes. Heaters for 460 VAC single phase current and non-standard lengths are available on special order.


  • Low Watt Density Heater
  • Thermostatically Controlled
  • Electric Immersion Type Fuel Oil Heater


Provide and install in the oil suction stub, inside each tank, one (1) Model SS __ __ Suction Stub Heater as manufactured by Preferred Utilities Mfg. Corp., Danbury, CT. Heater shall be of the low watt density type, thermostatically controlled and shall be complete with a cast iron water and vapor proof electrical junction box.