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This article describes 650-C chimneys, also called Super Chimneys designed for use with wood stoves and wood burning appliances.
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. Page top illustration of a 650-C chimney courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
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Super Chimneys, 629 Chimneys or 650-C Chimneys Replace Class-A Metal Chimneys & Flues
A 650-C Chimneys are required for use with wood burning stoves and, as Carson Dunlop's sketch explains, they have replaced Class A metal chimneys.
Type 650-C chimneys, also called Super Chimneys are tested for fire safety to 2000 deg.F. and provide an extra measure of fire safety.
Image at left: Selkirk 650C-rated insulated chimney installed using a cathedral ceiling support box.
650C chimneys, developed ca. 1983, are insulated and designed to withstand continuous flue gas temperatures of 650 degrees or less.
650-C chimneys are considered a suitable alternative to masonry chimneys used to vent woodstoves, heating appliances (boilers, furnaces, water heaters), and fireplaces.
Watch out: typically a 650-C chimney requires a 2-inch clearance to combustible framing or other combustibles. Depending on local building code approval, this distance can be reduced by appropriate heat shielding.
The 650-C or Super Chimnney is designed to resist corrosion both by its material and by the use of insulation that, by maintaining internal flue temperatures at a higher level (not as cooled by outside air) reduces the degree of condensation on the chimney flue interior.
Since Type A chimneys were discontinued for these applications after 1983 (to 1990 - citation needed), those venting systems are commonly replaced by a 650C chimney. [Type A chimneys do not have the same temperature tolerance and do not comply with current building codes in North America.]
Selkirk offers some important heating appliance and chimney safety advice concerning the 650C chimney illustrated above:
All chimneys should be inspected at least once a year to
determine that their physical integrity is being maintained.
The need for chimney maintenance also depends on the kind
of appliance and how it is operated.
Wood and coal-burning
appliances may need a great deal of chimney maintenance.
Open front fireplaces without doors usually dilute their smoke
with large amounts of air. Thus the buildup of chimney
deposits is generally very low.
“Air tight” or controlled draft
wood stoves and heaters produce dense smoke if they are
loaded for long duration or overnight fires, and can rapidly
produce heavy, thick creosote deposits. It is possible, by having
a short duration daily hot fire, to burn off these deposits or
prevent them from building up to dangerous levels.
This takes
skillful operation and an appreciation of how to get the correct
temperature. - Selkirk [1]
Definition of "Factory Built Chimney"
Factory-built chimney
means a
chimney
consisting entirely of factory-made parts, each designed
to be assembled with the other without requiring fabrication on site. - http://www.nationalcodes.nrc.gc.ca 11/13/2013
Super Chimney or 650C Chimney Product Sources & Standards
[1] "Installation Instructions for Roof Supported Model CF Chimney with a Cathedral Ceiling Support Box", Selkirk Canada, Inc., 1400 California Ave., PO Box 160, Brockville, Ontario K6V 5V3, Tel: 800-267-3620. Selkirk's product line includes a Model CF Chimney with a cathedral ceiling support box. [The author, DF, installed this type of chimney and support box - a design that permits the chimney to "hang" from the roof structure, making installation of a woodstove easier - Ed.] Available in 6", 7" and 8" chimney sizes (this is the internal flue diameter). Retrieved 11/14/2013, un-dated document.
[2] ASTM Standard ULCS629M 650C Factory-Built Chimneys, www.astm.org, U.S. standard retrieved 11/13/2013
[4] "Safety Tips Installing a Fireplace", Alberta Safety Council Suite 1000, 10665 Jasper Ave NW, Edmonton, Alberta T5J 3S9 Toll-free within Alberta: 1-888-413-0099 - Quoting: Factory-built chimneys serving solid-fuel-burning appli-
ances and their installation shall conform to CAN/ULC-
S629-M,
650°C Factory-Built Chimneys
. This document warns that "The chimney for a factory-built fireplace must be specifically designed, tested, and labeled for the particular unit".
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Reader Comments, Questions & Answers About The Article Above
Below you will find questions and answers previously posted on this page at its page bottom reader comment box.
(Mar 31, 2012) Caroline Slater said: We bought our detached house new from a builder on a development. There is a gas mains where the fire should go. The wall is an external wall. There is no obvious space where a flue would be. The builder told us we have a 'super flue' and that would allow us to install any gas fire. However a lot of gas fires require depth and all we have is a flat external wall. How can we tell if we have a super flue without causing damage to our property? Can we install a gas or wood burning stove if we have a super flue? What would be required if we did that? There is no chimney.
Reply:
Caroline, a "superflue" is a type of metal chimney. If one is actually installed in your home, you'd see it - or at least some sort of metal chimney - protruding above the roof. It may have been boxed in with wood framing or even built into the structure entirely depending on the home's design, but to be used it has to be accessible at bottom and top. Find the chimney, inspect the labels on it. Send me a photo if you can.
Before we know what sort of chimney is installed and where it is, we can't get far in thinking about where you can install a gas fireplace.
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In addition to any citations in the article above, a full list is available on request.
[1] "Installation Instructions for Roof Supported Model CF Chimney with a Cathedral Ceiling Support Box", Selkirk Canada, Inc., 1400 California Ave., PO Box 160, Brockville, Ontario K6V 5V3, Tel: 800-267-3620. Selkirk's product line includes a Model CF Chimney with a cathedral ceiling support box. [The author, DF, installed this type of chimney and support box - a design that permits the chimney to "hang" from the roof structure, making installation of a woodstove easier - Ed.] Available in 6", 7" and 8" chimney sizes (this is the internal flue diameter). Retrieved 11/14/2013, un-dated document.
[2] ASTM Standard ULCS629M 650C Factory-Built Chimneys, www.astm.org, retrieved 11/13/20133
[3] CAN/ULC- S629-M, 650°C Factory-Built Chimneys
[4] "Safety Tips Installing a Fireplace", Alberta Safety Council Suite 1000, 10665 Jasper Ave NW, Edmonton, Alberta T5J 3S9 Toll-free within Alberta: 1-888-413-0099 - Quoting: Factory-built chimneys serving solid-fuel-burning appli- ances and their installation shall conform to CAN/ULC- S629-M, 650°C Factory-Built Chimneys . This document warns that "The chimney for a factory-built fireplace must be specifically designed, tested, and labeled for the particular unit".
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
John Cranor [Website: /www.house-whisperer.com ] is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-873-8534 or by Email: johncranor@verizon.net
Thanks to Luke Barnes for suggesting that we add text regarding the hazards of shared chimney flues. USMA - Sept. 2008.
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
"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: CHIMNEY INSPECTION DIAGNOSIS REPAIR . 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
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.
Chimney & Stack Inspection Guidelines, American Society of Civil Engineers, 2003 - These guidelines address the inspection of chimneys and stacks. Each guideline assists owners in determining what level of inspection is appropriate to a particular chimney and provides common criteria so that all parties involved have a clear understanding of the scope of the inspection and the end product required. Each chimney or stack is a unique structure, subject to both aggressive operating and natural environments, and degradation over time. Such degradation may be managed via a prudent inspection program followed by maintenance work on any equipment or structure determined to be in need of attention. Sample inspection report specifications, sample field inspection data forms, and an example of a developed plan of a concrete chimney are included in the guidelines. This book provides a valuable guidance tool for chimney and stack inspections and also offers a set of references for these particular inspections.
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
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.