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Draft inducers guide: Here we explain Draft Inducers or Draft Booster Fans installed on oil fired heating equipment.

This website answers most questions about central heating system troubleshooting, inspection, diagnosis, and repairs. We describe how to inspect residential heating systems to inform home owners, buyers, and home inspectors of common heating system defects.

Details about draft control on oil fired heating systems (such as the oil fired heater shown in the photo above), including furnaces or boilers, are discussed right here at Draft Regulators barometric dampers on oil fired equipment. (Details about draft control for gas fired heating systems, including furnaces or boilers, are discussed at Furnace Draft Hood on gas fired equipment. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

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Draft Inducer Fans for Problem Chimneys & Vents

Draft inducers are special fans that are installed in the flue vent connector (or sometimes in the chimney) used to vent a heating boiler or furnace. Most often we see these installed on oil-fired systems at which the technician was unable to obtain sufficient natural draft for proper oil burner operation.

If an oil burner lacks adequate draft, as we discussed above, it will not operate properly, leading to soot clogging, more costly heating bills, back pressure in the combustion chamber, and possibly unsafe heater operation.

The draft inducer fan shown in our photo was found in our garage of left-over stock from our heating service days. This model, the Tjernlund DJ-3 Draft Inducer Fan is sold by Tjernlund in St. Paul, MN, and the photo shows the essential parts of this draft inducer:

• An electric motor (this one made by Fasco)
• A blower assembly of fan blades driven by the motor and designed to project into a metal flue pipe or flue vent connector
• An electrical junction box to connect the motor to the oil burner controls to turn the fan on and off when needed
• A metal shroud around the fan assembly

The draft inducer fan motor and wiring need to be adequately protected from the heat of the oil burner combustion gases, that's why you wouldn't try to make one of these at home out of an old computer fan or stereo system fan.

When is it not appropriate to install a draft inducer fan?

When Might We Need to Install a Draft-boosting Draft Inducer Fan?

How is a draft inducer fan installed?

A rectangular opening is cut into the metal flue pipe at a suitable location - usually close to the heating equipment since that makes wiring easier. The draft inducing fan comes with a paper template showing the size of the opening to cut.

The fan is mounted to the opening on the metal chimney or flue pipe so that its blades project into the flue, and so that when the fan motor runs it's pushing exhaust air away from the heating equipment and towards the chimney.

We've seen people install these fans in fireplace chimney flues in an effort to improve a fireplace that has inadequate draft, but we can't say if the manufacturer would approve that installation. There may be hazards due to creosote and other deposits from a wood-burning fireplace when one of these fans is used.

A note from Tjernlund informs us that draft inducer fan model DJ-2 has been replaced by Model DJ-3 and that all references in instructions to DJ-2 fans apply to DJ-3 models too.

Questions & Answers regarding this article

Questions & answers about bad draft on heating equipment & the use of draft inducer fans

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DRAFT REGULATORS, DAMPERS, BOOSTERS
  Purpose of Barometric Draft Regulator what is a barometric damper and why do we need them
  Measure Draft - how when where and why we measure draft and how we set the draft regulator
  Barometric Damper Defect List
  How to Inspect a Barometric Damper - how to look into the flue, what you'll see, what it means about heating system economy and condition
  Automatic Vent Dampers - how an automatic vent damper saves heating cost
  Define flue damper, duct damper, & fire damper
  Draft Inducer Fans - for solving draft and chimney problems

• Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

• Carbon Monoxide Gas Toxicity, exposure limits, poisoning symptoms, and inspecting buildings for CO hazards
• Fuel Oil & Oil Heating Magazine, 3621 Hill Rd., Parsippany, NJ 07054, 973-331-9545
• 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
• Plastic Heating Vent Pipe & Other Heating Safety Recall Notices
• 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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