Metal chimney not Type B Vent (C) Daniel Friedman

Single-Wall Metal Vents and Chimneys: Inspection, Diagnosis, Cleaning & Repairs
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Detailed Inspection & Photo Guide to single wall chimney defects
Obsolete single wall metal fireplace chimneys
Unsafe, damaged single wall metal chimney used for venting a gas appliance
Questions & answers about single wall metal chimneys & flues: installation, fire clearances, troubleshooting, maintenance

Single wall metal chimneys: this article describes Single-Wall Metal Vents and Chimneys, their Inspection, Diagnosis, Cleaning & Repairs.

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Single-Wall Metal Vents and Chimneys

Readers of this section should also be sure to review details at Flue Vent Connectors - Boilers, Furnaces. This article series on chimneys, chimney construction, and chimney safety provide detailed suggestions describing how to perform a thorough visual inspection of chimneys for safety and other defects. Chimney inspection methods and chimney repair methods are also discussed.

The single wall metal fireplace chimney shown at page top was installed in a solid masonry fireplace in the 1960's. It can no longer be safely used because of the new construction in the left of the photo. This chimney will need to be replaced with a modern insulated flue and extended in height.

The metal chimney shown at left is not a Type B gas vent and may be unsafe. Certainly it should not be in use for venting a heating appliance.

Do not mistake this single-walled vent for a Type-L vent nor for a Type-B vent even though a hasty glance may make it look like one of those.

This vent appears to be single-walled aluminum and it has what looks almost like a coffee can installed as a rain cap.

If the metal chimney we see in this photo is being used to "vent" a water heater it is probably not working and probably lacks adequate draft. The result may be carbon monoxide release in the building.

Single-wall metal pipes used to connect heating appliances to chimneys (metal or masonry) are discussed separately at Single-Wall Metal Flue Vent Connectors where we provide details about single wall metal flues and their fire clearance requirements.

Single wall metal pipes are also described in our table listing clearances by gas-fired appliance type at Listed Flue Vent Connectors for Gas Fired Heating Appliances.

Also see Metal Chimney Safety Alert - CPSC Document #5047.

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Questions & answers about single wall metal chimneys & flues: installation, fire clearances, troubleshooting, maintenance.

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Metal Chimneys & Flues
  Bracing for Metal Chimneys
  Class A Chimneys, MetalBestos™
  Connecting Metal Chimney Sections
  Continuous metal chimneys
  Definitions of Chimney Types & Parts
  Fire Clearances for Metal Chimneys
  Height required for L Vents & B Vents
  Indoor Hazards, Metal Chimney & Vent
  Manufactured Chimneys
  Offset from Vertical in Chimneys, excessive
  Replacement Components for Metal Chimneys
  Single-Wall Metal Vents & Chimneys
  Super Chimneys, 629 Chimneys
  Triple-Wall Metal Fireplace Chimneys
  Type B-Vents
  Type L Vents
  Wet time & Corrosion in Chimneys, Vents
  Wood Framed Chimney Chases

NFPA 211 - Standards for Chimneys & Fireplaces, NFPA 211: Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances, 2006 Edition (older editions and standards are found at the same bookstore)
NFPA #211-3.1 1988 - Specific to chimneys, fireplaces, vents and solid fuel burning appliances.
NFPA # 54-7.1 1992 - Specific to venting of equipment with fan-assisted combustion systems.
GAMA - Gas Appliance Manufacturers' Association has prepared venting tables for Category I draft hood equipped central furnaces as well as fan-assisted combustion system central furnaces.
National Fuel Gas Code, an American National Standard, 4th ed. 1988 (newer edition is available) Secretariats, American Gas Association (AGA), 1515 Wilson Blvd., Arlington VA22209, and National Fire Protection Association (NFPA), Batterymarch Park, Quincy MA 02269. ANSI Z223.1-1988 - NFPA 54-1988. WARNING: be sure to check clearances and other safety guidelines in the latest edition of these standards.
Fire Inspector Guidebook, A Correlation of Fire Safety Requirements Contained in the 1987 BOCA National Codes, (newer edition available), Building Officials and Code Administrators International, Inc. (BOCA), Country Club HIlls, IL 60478 312-799-2300 4th ed. Note: this document is reissued every four years. Be sure to obtain the latest edition.
Uniform Mechanical Code - UMC 1991, Sec 913 (a.) Masonry Chimneys, refers to Chapters 23, 29, and 37 of the Building Code.
New York 1984 Uniform Fire Prevention and Building Code, Article 10, Heating, Ventilating, and Air Conditioning Requirements
New York 1979 Uniform Fire Prevention & Building Code, The "requirement" for 8" of solid masonry OR for use of a flue liner was listed in the One and Two Family Dwelling Code for New York, in 1979, in Chapter 9, Chimneys and Fireplaces, New York 1979 Building and Fire Prevention Code:
"Top Ten Chimney (and related) Problems Encountered by One Chimney Sweep," Hudson Valley ASHI education seminar, 3 January 2000, contributed by Bob Hansen, ASHI
Chimney Inspection Checklist, Carson Dunlop, Associates, Toronto, Ontario
"Rooftop View Turns to Darkness," Martine Costello, Josh Kovner, New Haven Register, 12 May 1992 p. 11: Catherine Murphy was sunning on a building roof when a chimney collapsed; she fell into and was trapped inside the chimney until rescued by emergency workers.
"Chimneys and Vents," Mark J. Reinmiller, P.E., ASHI Technical Journal, Vol. 1 No. 2 July 1991 p. 34-38.
"Chimney Inspection Procedures & Codes," Donald V. Cohen was to be published in the first volume of the 1994 ASHI Technical Journal by D. Friedman, then editor/publisher of that publication. The production of the ASHI Technical Journal and future editions was cancelled by ASHI President Patrick Porzio. Some of the content of Mr. Cohen's original submission has been included in this more complete chimney inspection article: InspectAPedia.com/chimneys/Chimney_Inspection.htm. Copies of earlier editions of the ASHI Technical Journal are available from ASHI, the American Society of Home Inspectors.
Natural Gas Weekly Update: http://tonto.eia.doe.gov/oog/info/ngw/ngupdate.asp Official Energy Statistics from the U.S. Government
US Energy Administration: Electrical Energy Costs http://www.eia.doe.gov/fuelelectric.html

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.
NFPA 211 - 3-1.10 - Relining guide for chimneys
NFPA 211 - 3-2 - Construction of Masonry Chimneys
NFPA 211 - 3-3 - Termination Height for chimneys
NFPA 211 - 3-4 - Clearance from Combustible Material
NFPA 54 - 7-1 - Venting of Equipment into chimneys
Brick Institute of America - Flashing Chimneys
Brick Institute of America - Proper Chimney Crowns
Brick Institute of America - Moisture Resistance of Brick
American Gas Association - New Vent Sizing Tables
Chimney Safety Institute of America - Chimney Fires: Causes, Effects, Evaluation
National Chimney Sweep Guild - Yellow Pages of Suppliers
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Single-Wall Metal Vents and Chimneys

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