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Guide to Heating System Oil Burners HeatAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

Here we discuss Oil Burners: Guide to Oil Burners for heating systems, boilers & Furnaces: basic parts, operation, maintenance, performance & money-saving tips and readers will also find that this website answers most questions about central heating and water heating systems to aid in troubleshooting, inspection, diagnosis, and repairs.

Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Homeowner's Guide to Oil Burners for Boilers, Furnaces, & Water Heaters

Oil fired heating equipment such as hydronic (hot water) boilers, steam boilers, warm air furnaces, and water heaters, have used heating oil, usually No. 2 heating oil, and various types of oil burners to burn the fuel, thus providing a heat source for nearly 100 years. Here we describe the basics of how oil burners work, and we provide a guide to their inspection and problem diagnosis and repair.

How Oil Burners Work

Refer to the schematic of a conventional oil burner shown below, where we list the major parts parts of a modern oil burner. The sketch is courtesy of Carson Dunlop.

Sequence of steps in home heating or hot water heater oil burner operation:

1. Electric power on: In response to an aquastat or other heating boiler, furnace, or water heater control, electrical power to the oil burner is switched "on". Electricity is connected through a safety control such as the Cad Cell relay labeled "primary controller" in the sketch. Details: Aquastat, Cad Cell Relay
   
   
2. Oil burner electric motor starts: The primary controller permits electrical power to flow to the electric motor shown on the right side of the oil burner, causing the motor shaft (not shown) to rotate.
   
   
3. Motor shaft rotates, driving other parts: the spinning shaft of the electric motor extends horizontally through the inside of the oil burner motor where it is coupled first to a rotating squirrel cage fan - the oil burner's air blower (providing combustion air), and second to the the air blower and oil pump (fuel unit). High speed oil burner motors spin at 3450 RPM. Older "low speed" (and quieter) oil burners use an electric motor rotating at 1725 rpm.
   
   
4. Combustion air: Oil burner blower fan spins, drawing combustion air through adjustable air intake slots on the left side of the oil burner, and simultaneously,
   
   
5. Heating oil delivery: the electric motor shaft extension drives the oil pump (fuel unit) shown on the left-most side of the oil burner in the sketch. The oil pump draws heating oil from the oil tank through a fuel line connected to the oil tank (hopefully through an external oil filter and an internal filter screen) and pressurizes the heating oil to 100 psi or more. Pressurized heating oil flows out of the oil pump thorugh a high pressure oil line into the oil burner tube where it is converted to a fine spray by an oil nozzle attached to the end of the nozzle assembly. See OIL TANKS, OIL TANK PIPING DEFECTS
   
   
6. Heating oil ignition: electricity is also delivered to an ignition transformer (the black box on top of the back of the oil burner). The ignition transformer converts the incoming 120V electrical power to very high voltage which is fed to two electrodes attached to the nozzle assembly. The nozzle electrodes, separated by a small gap, produce an electrical spark (usually continuously) which is right in the path of the oil being sprayed by the oil burner nozzle, causing the oil to ignite.
   
   
7. Heating oil combustion: the sprayed, burning heating oil heats the interior of the furnace, boiler, or water heater combustion chamber which is normally lined with a material whose surface will get very hot but won't burn. The combustion chamber liner prevents the oil burner from damaging the cast iron or steel boiler itself, while the hot surface of the combustion chamber liner helps make sure that all of the fine droplets of oil sprayed into the combustion chamber do in fact ignite.
   
   
8. Heat transfer: hot combustion gases from the burning heating oil flow (usually upwards) through the furnace, boiler, or water heater heat exchanger where they transfer heat to that appliance before continuing to flow through a flue vent connector (stack pipe) and then outside through a chimney. See: BOILERS, CHIMNEYS, FURNACES, STEAM HEATING, WATER HEATERS
   
   
9. Electric power and oil burner off: when the aquastat, thermostat, or other primary control senses that the desired temperature has been reached, electric power to the oil burner is turned off, stopping the electric motor from spinning, thus stopping the combustion air blower, oil pump, and turning off the ignition transformer.

Technical Reviewers

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Daniel Friedman - InspectAPedia.com ^TM Website Author/Editor
• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

More expert information on this topic

More Information on Inspecting and Repairing Heating Systems

• Carbon Dioxide Gas Toxicity
• Carbon Monoxide Gas Toxicity, exposure limits, poisoning symptoms, and inspecting buildings for CO hazards
• Dust from HVAC? An Investigation of Indoor Dust Debris Blamed on a Heating/Cooling System Reveals Carpet Dust
• Goodman Furnace High Temperature Plastic Vent HTPV safety recall US CPSC notice
• Home Heating System Should Be Checked [for proper venting and for CO Carbon Monoxide Hazards - DJF]
• Inspection Procedures for Oil-Fired Heating Systems Detailed step by step approaches for inspecting complex systems]
• Lennox Pulse Furnace Safety Inspection/Warranty Program: Carbon Monoxide Warning
• Oil Tanks - The Oil Storage Tank Information Website: Buried or Above Ground Oil Tank Inspection, Testing, Cleanup, Abandonment of Oil Tanks
• Oil Tanks Above Ground, UL Standards, guidance for home owners, buyers, and inspectors
• Plastic Heating Vent Pipe & Other Heating Safety Recall Notices
• Weil McLain Model GV Gas Boiler/gas valve CPSC recall/repair
• Domestic and Commercial Oil Burners, Charles H. Burkhardt, McGraw Hill Book Company, New York 3rd Ed 1969.
• National Fuel Gas Code (Z223.1) $16.00 and National Fuel Gas Code Handbook (Z223.2) $47.00 American Gas Association (A.G.A.), 1515 Wilson Boulevard, Arlington, VA 22209 also available from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269. Fundamentals of Gas Appliance Venting and Ventilation, 1985, American Gas Association Laboratories, Engineering Services Department. American Gas Association, 1515 Wilson Boulevard, Arlington, VA 22209. Catalog #XHO585. Reprinted 1989.
• The Steam Book, 1984, Training and Education Department, Fluid Handling Division, ITT [probably out of print, possibly available from several home inspection supply companies] Fuel Oil and Oil Heat Magazine, October 1990, offers an update,
• Principles of Steam Heating, $13.25 includes postage. Fuel oil & Oil Heat Magazine, 389 Passaic Ave., Fairfield, NJ 07004.
• The Lost Art of Steam Heating, Dan Holohan, 516-579-3046 FAX
• Principles of Steam Heating, Dan Holohan, technical editor of Fuel Oil and Oil Heat magazine, 389 Passaic Ave., Fairfield, NJ 07004 ($12.+1.25 postage/handling).
• "Residential Steam Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
• "Residential Hydronic (circulating hot water) Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
• "Warm Air Heating Systems". Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
• Heating, Ventilating, and Air Conditioning Volume I, Heating Fundamentals,
• Boilers, Boiler Conversions, James E. Brumbaugh, ISBN 0-672-23389-4 (v. 1) Volume II, Oil, Gas, and Coal Burners, Controls, Ducts, Piping, Valves, James E. Brumbaugh, ISBN 0-672-23390-7 (v. 2) Volume III, Radiant Heating, Water Heaters, Ventilation, Air Conditioning, Heat Pumps, Air Cleaners, James E. Brumbaugh, ISBN 0-672-23383-5 (v. 3) or ISBN 0-672-23380-0 (set) Special Sales Director, Macmillan Publishing Co., 866 Third Ave., New York, NY 10022. Macmillan Publishing Co., NY
• Installation Guide for Residential Hydronic Heating Systems
• Installation Guide #200, The Hydronics Institute, 35 Russo Place, Berkeley Heights, NJ 07922
• The ABC's of Retention Head Oil Burners, National Association of Oil Heat Service Managers, TM 115, National Old Timers' Association of the Energy Industry, PO Box 168, Mineola, NY 11501. (Excellent tips on spotting problems on oil-fired heating equipment. Booklet.)

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