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Fuel Oil Heaters information

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FUEL OIL HEATERS Frequently Asked Questions:

FUEL OIL HEATERS applications include:

  • #2 Fuel Oil

  • #4 Fuel Oil

  • #6 Fuel Oil  

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FUEL OIL HEATERS are used to heat primarily #2, #4 or #6 fuel oils to a desired operating temperature.  Warren Electric Corporation Fuel Oil Heaters are U.L. listed, tubular element heaters designed from 1 KW to 100 KW for mounting via our 4 ½” O.D. special flange, 3” ANSI Flange or 6” ANSI flange.   A standard fuel oil thermostat (100 degrees F to 225 degrees F) with or without cold oil interlock is a part of each heater. 

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How do you size FUEL OIL HEATERS?


FUEL OIL HEATERS are sized by using the following information:

  • Volume to be heated
  • Dimensions and capacity of tank
  • Thickness of insulation on tank (if any)
  • Temperature to maintain, worst case ambient temperature and desired heat-up time if tank is allowed to cool during non-operating periods
  • Available operating Voltage & Phase
  • Environmental operating conditions to select the proper terminal enclosure
  • Standard 100-225 Degrees F Fuel Oil Thermostat (with or without Cold Oil Interlock)
  • Flow rate, Desired Inlet & Outlet Temperatures if heater will be used in a casing  

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FUEL OIL HEATERS are used by the following business, industries, and locations:

  • Green Houses

  • Property Management

  • Apartment Complexes

  • Hospitals                                                                      

  • Manufacturing Buildings

  • Commercial Buildings

  • Oil Burner Manufactureres 

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How long is delivery for FUEL OIL HEATERS?


FUEL OIL HEATERS can usually be shipped in one to two weeks if parts are in stock.  If parts are not in stock, it can take up to six weeks to ship.

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How are FUEL OIL HEATERS installed?


FUEL OIL HEATERS are installed horizontally near the bottom of the tank/reservoir of in a casing. In either case, the heated portions of the heater elements must remain completely immersed and completely flooded whenever energized.  The cold section of the heater should be extended completely into the fuel oil.  The heater may overheat, damaging the elements, tank or fluid being heater and/or create a possible safety hazard due to high sheath temperature.  It may also cause the heater to become stuck in the casing due to major coking.    (See INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS)

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What is the Quality Policy and Warranty on FUEL OIL HEATERS ? 


Warren Electric Corporation FUEL OIL HEATERS must pass vigorous inspections prior to shipment.  Each individual heating element is checked for electrical leakage and breakdown at high voltage before assembly.  All heaters are 100% hydrostatically pressure tested to insure braze or wells attaching the element to the flange is free of all leaks.  We also electrically test 100% of heaters to ensure they meet the wattage/voltage specifications of the order.  100% of our heaters are also subject to testing for moisture content and hipot testing.  Every heater that Warren Electric Corporation has ever manufactured is identified with a serial number prior to shipment.  These serial numbers are kept on file indefinitely and can be used to identify back to the original inspection sheet and purchase order.   Warranty is 15 months from the date of shipment provided heater failure is not caused by operator error.

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Are there any special certifications available for FUEL OIL HEATERS? 


There are third party certifications and inspections available for fuel oil heaters including UL.

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How do you clean FUEL OIL HEATERS?

If you notice a build up of oil (called coke) burned onto the elements of the FUEL OIL HEATERS,  the heater elements only can be soaked in kerosene to break down the coke and a wire brush can be used to remove the excess build up if necessary. 

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How do you adjust  FUEL OIL HEATERS Thermostat with a Cold Oil Interlock? 


Models equipped with an auxiliary interlock switch are factory adjusted to close the interlock switch at a temperature setting of 125 degrees F.  If a higher or lower interlock setting is desired, just turn the small brass knurled knob located directly under the dial pointer in accordance with the directions on the nameplate of the heater. 

If the interlock is set higher than the oil temperature, the auxiliary interlock switch will prevent your burner from operating and the heater will stay off. 

If this occurs, either lower the interlock setting or raise the oil temperature.  This feature is in the design to minimize incorrect adjustment and function of your heater interlock control.

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