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Combustion Air Requirements for Power Burners Combustion Air Guidelines
POST a QUESTION or COMMENT about combustion air requirements and safety hazards for oil and gas fired heating appliances
Combustion air defects & hazards for power burners:
This article series explains how to recognize and fix combustion air defects on heating appliances such as boilers, furnaces, and water heaters. These articles answer most questions about central hot water heating system troubleshooting, inspection, diagnosis, and repairs. Our photo at page top shows an oil fired furnace installed in a closet with an airtight door; there was no outside combustion air supply. The heating system could not work properly nor safely in this home.
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Combustion Air Requirements Specifications for Power Burners
For combustion air requirements for power burner fired heating appliances we excerpt research by Utiskul (2012) cited in theReferences or Citations for this article. Utiskul, writing for the NFPA discusses NFPA 54 cited by U.S. heating appliance manufacturers for combustion air standards, and in Canada, CSA B149.1-10 (which gives different criteria).
Excerpting notes on combustion air for power burners the author notes:
NFPA 54 requires the largest outdoor openings for combustion air in comparison to the other
referenced guidelines. The opening free area required by NFPA 54 ranges from 0.33 to 1 square
inch per kBtu/hr input rating, depending on the number of the openings and how they
communicate with the outdoors.
The other guidelines require combustion air openings with free
area ranging from 0.08 to 0.14 square inches per kBtu/hr, which is consistent with providing an
additional approximately 30% air supply to the combustion process. CSA B149.1-10 contains a
separate provision for appliances equipped with power burners to supply combustion air with
outdoor openings sized to 0.03 square inches per kBtu/hr of the total burner input rating.
Power burner boilers have the highest
range of energy input ratings (60,000 to 83,600,000 Btu/hr) in comparison to that of water
heaters (60,000 to 40,300,000 Btu/hr) and furnaces (30,000 to 9,800,000 Btu/hr).
A majority of
the manufacturers (60%) included in this study reference NFPA 54 for combustion air
requirements (0.33 to 1 square inches per kBtu/hr input) for their power burner appliances with
energy inputs ranging from 30 to 92,000 kBtu/hr. Of the 25 manufacturers, eight recommend
that combustion air be provided by openings sized to 0.03 to 0.75 square inches per kBtu/hr of
the total appliance input rating from 150 to 83,600 kBtu/hr.
The opening size in accordance January 30, 2012
QMS QA ID No. 1103894.000 B0F0 0112 YU01 50
with these eight manufacturers is approximately 25% to 97% smaller than that of the NFPA 54
requirements. The remaining manufacturers recommend combustion air requirements based on
a specified volumetric flow rate from 0.24 to 0.47 cfm per kBtu/hr of appliance input rating.
Based on the review of available literature data, a review of the manufacturer’s requirements for
combustion air, the investigation of the combustion air required for power burners, and the
theoretical analysis of air flows through openings, sizing criteria for combustion air openings for
power burner appliances are theorized as follows:
A minimum opening area of 0.2 square inches per kBtu/hr input rating for power burner
appliances equipped with a draft control device; and
A minimum opening area of 0.1 square inches per kBtu/hr input rating for power burner
appliances that require no dilution of flue gases.
Based on the theoretical analysis provided in this study, these theorized combustion air
requirements should provide an adequate amount of combustion air for proper appliance
operation and will optimize overall building efficiency by reducing unnecessary area in
openings. It is strongly recommended the theorized sizing criteria be validated through fullscale
field experiments, which will provide a basis for new code development. - Utiskul (2012)
Combusion Air for Power Burners, Research & Standards
Utiskul, P. Yunyong, Ph.D. P.E., Wu, Neil P., P.E., BIteau, Hubert, Ph.D., "Combustion Air Requirements for
Power Burner Appliances, Final Report", [PDF], The Fire Protection Research Foundation, One Batterymarch Park
Quincy, MA, USA 02169-7471
Email: foundation@nfpa.org
http://www.nfpa.org/foundation, retrieved 2016/06/21, original source: http://www.nfpa.org/~/media/files/research/research-foundation/rfcombustionairrequirements.pdf?la=en
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In addition to any citations in the article above, a full list is available on request.
American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Handbook - Fundamentals, 1993, Chapter 15, page 15.9 Air For Combustion.
ASME CSD-1- Controls and Safety Devices for Automatically Fired Boilers, 1992 with addendum 1a 1993. section CG-260 Combustion Air.
BOCA - National Mechanical Code, 1990, article 10, Combustion Air.
NFPA 31 - Installation of Oil Burning Equipment, 1992, section 1-5 Air for Combustion and Ventilation.
NFPA 54: National Fuel Gas Code (2015), addresses heating appliance combstion air ventilation specifications. NFPA 54, ANSI Z223.1 provides minimum safety requirements for the design and installation of fuel gas piping systems in homes and other buildings.
NFPA 85: Boiler and Combustion Systems Hazards Code: NFPA 85 contributes to operating safety and prevents explosions and implosions in boilers with greater than 12.5 MMBTUH, pulverized fuel systems, and heat recovery steam generators.
NFPA 87: Recommended Practice for Fluid Heaters, This recommended practice provides safety guidance for fluid heaters and related equipment to minimize fire and explosion hazards that can endanger the fluid heater, the building, or personnel
SBCCI- Standard Mechanical Code, 1991, section 305 Combustion and Ventilation Air.
Axtman, William H., "Combustion Air Requirements: The Forgotten Element in Boiler Rooms", Grayh Gull Associates, retired executive director of the American Boiler Manufacturers Association, National Board Technical Series, Winter 1995 National Board Bulletin. Retrieved 26 January 2015, original source: http://www.nationalboard.org/index.aspx?pageID=164&ID=191 Excerpt: Several safety codes such as the National Fire Protection Association's standards, NFPA 54 - National Fuel Gas code, NFPA 31 - Installation of Oil Burning Equipment, and the American Society of Mechanical Engineers (ASME) CSD-l Controls and Safety Devices for Automatically Fired Boilers have sections covering the requirements for combustion air intakes. In addition, building codes such as the Building Officials and Code Administrators International (BOCA) National Mechanical Code and the Standard Mechanical Code published by the Southern Building Code Congress International (SBCCI) have air requirements for combustion. Editor's note: Some ASME Boiler and Pressure Vessel Code requirements may have changed because of advances in material technology and/or actual experience. The reader is cautioned to refer to the latest edition and addenda of the ASME Boiler and Pressure Vessel Code for current requirements.
Nussbaumer, Thomas. "Combustion and co-combustion of biomass: fundamentals, technologies, and primary measures for emission reduction." Energy & fuels 17, no. 6 (2003): 1510-1521.
Utiskul, Yunyong P., Wu, Neil P., Biteau, Hubert, "Combstion Air Requirements for Power Burner Appliances, Final Report", The Fire Protection Research Foundation, The Fire Protection Research Foundation One Batterymarch Park Quincy, MA, USA 02169-7471 Email: foundation@nfpa.org http://www.nfpa.org/foundation, retrieved 25 Jan 2015, original source: http://www.nfpa.org/~/media/files/research/research%20foundation/rfcombustionairrequirements.ashx, Executive Summary: Gas-fired appliances require combustion air to properly function. Adequate air is necessary for supporting combustion of the appliance burner, dilution of flue gas, and proper ventilation of the space where the appliance is installed. Current standards and model codes outline requirements and methods to supply the combustion air. One method is to provide outdoor combustion air through openings or air ducts communicating with the outdoors through natural ventilation. Most standards require the outdoor opening(s) be prescriptively sized based on the total energy input rating of the appliance. However, in the United States, the current standards contain no separate provisions to address the opening size supplying the combustion air for commercial/industrial sized appliances, which typically have a high energy input rating of greater than 300 kBtu/hr and are equipped with a power burner unit. As a result, the opening(s) can be excessively sized when determined based on the current standards. This research project establishes minimum outdoor combustion air requirements specific to gasfired appliances utilizing power burners with input ratings no greater than 12.5 MBtu/hr. A review of the available literature, engineering guidelines, and current standards and model codes related to combustion air requirements was performed. This report provides an understanding of the technical basis for the existing provisions for combustion air and their applicability to power burner appliances. This report also identifies the range of energy input ratings for gasfired appliances equipped with power burners, and compares the combustion air requirements specified by a range of appliance manufacturers. A theoretical model for air flow through openings was developed and the modeling results, together with the data gathered through the literature review, were used to provide a baseline to establish the theorized combustion air requirements suitable for power burner appliances. ...
[1] Jeff Wilcox, "Evaluating Duct Work, How to Evaluate Furnace Duct Work & Cure Short Cycling or Inadequate Ductwork Problems" Vermont Department for Children and Families, Office of Economic Opportunity, - dcf.vermont.gov/sites/dcf/files/pdf/oeo/WAPManual/AppendixI.pdf retrieved 12/5/2013. Geoff Wilcox
Vermont Office of Economic Opportunity
Weatherization Assistance Program
Waterbury, VT
(802) 769-8376
Geoff.wilcox@state.vt.us
Reference Material for the original article came from:
1. Saturn Mechanical Systems Field Guide
2. Bacharach (Rudy Leatherman)
Field Controls provides instructions for the installation of LP and Natural Gas spill sensor switches, for example for their Gas Spillage Sensing Kit Model GSK-3, GSK-4, GSK-250M switches. Contact your heating service technician directly, or contact Field controls at fieldcontrols.com for more information. These switch models include a manual reset switch. Field Controls, Kingston NC 28504 - Tel 252-522-3031.
Tjernlund Products provides instructions for the installation and use of their controls, including the WHKE Millivolt Interlock Kit for use with their UC1 Universal Control, MAC1E or MAC4E auxiliary controls for gas fired equipment. This document also describes Tjernlund's recommended combustion air safety check which we recommended in this article. Contact Tjernlund Products at tjernlund.com or at 800-255-4208.
Bachrach Corporation, www.bachrach-training.com provides education for HVAC technicians. We found their web pages hanging during loading -01/2009. Readers may want to contact the company directly at: bacharach-inc.com or at 800-736-4666.
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.
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 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.)
In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: info@carsondunlop.com. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Carson Dunlop Associates provides extensive home inspection education and report writing material. In gratitude we provide links to tsome Carson Dunlop Associates products and services.