Automatic vent dampers save energy and lower heating cost fuel bills
How does an automatic vent damper work
When, where, and why is an automatic vent damper or "flue vent damper" installed?
Inspection guide to flue vent dampers on oil fired heating equipment
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Here we discuss Automatic flue vent dampers, what they are, how they work, and why they can save money on heating bills. Page top sketch courtesy of Carson Dunlop.
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.
The articles at this website describe the basic components of a home heating system,
how to find the rated heating capacity of an heating system by examining various data tags and components, how to recognize common heating system operating or safety defects, and how to save money on home heating costs.
We include product safety recall and other heating system hazards.
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.
Heating costs can be reduced by any measure that makes sure that as much as possible of the warmth produced by burning a heating fuel (such as natural gas) is sent into the occupied space rather than lost elsewhere.
An automatic vent damper, such as illustrated in Carson Dunlop's sketch here and in our photograph just below, reduces heat loss in buildings where gas-fired heaters are installed.
When the heater is off the electric motor turns the vent damper to the "closed" position so that heat is not lost from the boiler nor the building by natural convection.
When the heater is about to turn on, before the burner is ignited the automatic vent damper motor opens the vent so that combustion gases can flow freely through the flue vent connector and out of the building's chimney.
Don't confuse an automatic flue vent damper with two other "damper" devices: a heating system automatic duct damper or a duct fire damper.
Exactly what is an automatic flue damper?
An automatic flue damper is a device which closes the heating flue when the furnace or boiler is "off" so that we won't continue to lose building heat up the chimney - it's a device to reduce heating costs and save on heating oil consumption.
When the heating system has turned off at the end of an "on" cycle of burning fuel, the automatic flue damper electric (see sketch above and photo at left) motor turns a baffle inside of the flue vent connector pipe to a position "across" the pipe so that the airflow inside the pipe is blocked or stopped.
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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.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
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,
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
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The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems
Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.