Flexible HVAC duct sources, suppliers, list of manufacturers:

This article lists sources of suppliers of flexible insulated ductwork used in heating and air conditioning systems or where insulated flexible ductwork is needed for other applications such as venting moist exhaust air through un-conditioned attics, basements or crawl spaces.

Suppliers of Insulated HVAC Flex Duct - where to buy flexible ductwork

Watch out: Be sure to check the diameter and duct lengths you need before ordering any product. Excessive duct length beyond what's needed as well as extra bends and curves, kinks or improper duct upport interfere with good air flow rates. For details review our flex-duct installation specifications at DUCT ROUTING & SUPPORT.

Remember to also purchase the necessary cable ties, duct tape or other connecting accessories to support flexible ductwork properly and to make your duct connections air tight and secure.

• Home & building suppliers such as Home Depot or Lowes or your local building supplier. See lowes.com or homedepot.com for online sales by these companies.
• Atco insulated flexible dutwork
• DuctSox® is a flexible fabric textile-type flexible ductwork supplier. DuctSox Corporation 9866 Kapp Court Peosta, IA 52068 Phone: 563-588-5300 • 866-563-7729 Fax: 563-588-5330, Website: http://www.ductsox.com/
• FanTech 6-inch foil-covered, plastic lined 6" flexible duct in 25-foot lengths sells for about $30. U.S. The product is distributed through HVAC suppliers and online suppliers such as SupplyHouse.com Tel: 1-888-757-4774
• Grainger, an enormous supplier provides a range of flexible air duct products in both insulated and non-insulated forms for HVAC as well as fan and ventilation applications. Contact Grainger in the U.S. at 1-800-GRAINGER or at the company's website: www.grainger.com
• Hart & Cooley provides residential & commercial flexible HVAC ductwork in a variety of product forms and sizes including polyethylene-covered UV_resistant flex duct and metalized polyester covered flex-duct. Contact Hart Cooley, 5030 Corporate Exchange Blvd. SE Grand Rapids, MI 49512 P (800) 433-6341 F (800) 223-8461 Email: info@hartcool.com, website: http://www.hartandcooley.com/
• Imperial provides 3" x 8 ft. aluminum general purpose flex duct at about $9. U.S. distributed through HVAC suppliers and online suppliers
• Lambro provides aluminum covered insulated flexible ductwork used for transition ductwork and for increased fire resistance. 4" x 8 ft. @ $11. U.S. distributed through HVAC suppliers and online suppliers
• Snappy 6-inch x 25 ft. fiberglass insulated flex duct is sold in 25-foot lengths for about $26. U.S. In larger 14-inch diameter the cost is about $63. U.S. per 25 foot length.
• Speedi-Products sells foil covered plastic lined insulated flexible ductowrk, for example their model # FD-25R4 12 is sold in 12" diameter and 24 foot lengths for about $25. U.S. The product is distributed through HVAC suppliers and online suppliers.
• Un-insulated wire-reinforced mylar flex-duct of various diameters, not something we recommend for HVAC installations in most situations, is sold by Jon-Don at www.jondon.com

Reader Question: what are the origin and history of flex-duct?

2016/02/10 Douglas Gulley said:

Dear Inspectapedia, Regarding the invention & history of flexible ducting - it seems like I have a memory of some well respected, senior member of the hvac industry making a reference to the idea that flex duct in the hvac industry is only accidental & happenstance as the original flex duct was designed for use in a wholly different industry & context

.(Not that it wouldn't of happened eventually anyway...) Problem is I can't remember the story with surety (perhaps the reference was to duct tape...) nor is googling any help. How about it? Any stories from the early times that might be relevant? Thanks in advance!

Reply: history of flexible air ducts reflected in U.S. patents

Certainly flexible ducting has been around for more than 150 years and may have originated with flexible elbows for metal flue vent connector. A research of U.S. patent history gives us insight into the history and development of flexible hoses and duct systems. I found citations dating back to the late 1800's and in applications such as flexible air hoses for connections between train cars, flexible metal elbows on flue vent connectors or metal chimneys, and other uses.

Modern wire coil, fiberglass, and plastic covered (and hopefully lined) flex-duct is a more recent invention. But rubber, metal, and fabric all had roles in both the original and ongoing materials and uses of flexible hoses, tubing, and ductwork.

Patents reflecting the history of the development of flexible HVAC air ducts are arranged below in rough chronological order

Shown above: silver-jacketed plastic-lined, fiberglass-insulated flexible air ducts from JPL, a U.S. air duct manufacturer, website: www.jpflex.com, Tel: 800-255-3539

I may have missed some important ones and will add more as they come to hand, but these patent descriptions give an interesting view of the development of flexible ductwork. Some of these patent citations have been edited for clarity or to correct apparent patent text scanning errors.

• Laubsch, Carl L. "Carl l." U.S. Patent 568,537, issued September 29, 1896.
  This invention relates to adjustable pipe sections or elbows, but more particularly to adjustable elbows for stove or smoke-conveying pipes.
• Milton, Osborn. "Stovepipe attachment." U.S. Patent 1,661,674, issued March 6, 1928.
  
  This invention relates to stove pipes and more particularly to lock joints therefor. The primary object of the invention is to provide a lock joint for securing telescopic ends of pipe sections together to provide a substantial rigid joint that necessitates rotation of the pipe sections before the joint can be disconnected.
  
  Another object of invention is to provide a pipe joint of simple and inexpensive nature and one that is automatic in its connecting action, such action consisting in merely telescoping the ends of the sections and the locking means will snap in operative position.
• A similar invention in piping was patented in the 1930's
  Elkins, Philip D, "Coupling." U.S. Patent 1,891,874, issued December 20, 1932.
• Brown, Wallace, E., "Flexible noncollapsible tubing." U.S. Patent 2,091,265, issued August 31, 1937.
  
  This invention relates to tubing or hose which may be used for the ventilation of mines and underground excavations, for transporting fluids in industrial operations and the like, and especially to a tubing or hose constructed in part of collapsible rubberized fabric and combined in such a manner as to be useful to transport air or other gases under reduced atmospheric pressures.

• By 1937 flex duct was discussed in this patent:
  Lambert, Robert D. "Duct." U.S. Patent 2,089,492, issued August 10, 1937.
  
  ...square or rectangular ducts formed of sheet metal, but such ducts are inadequate to meet the present day needs in that they are relatively diilicult and expensive to install and because they transmit both the sounds of moving air and the i[?] mechanical sounds of the apparatus to the rooms of the building to winch the ducts areconnected.
  
  An object of the present invention is to provide a relatively inexpensive duct which is strong vand durable, which will eectively absorb sound waves, which may be readily cut into any desired length with ordinary carpenters tools and which may be easily installed with a minimum of labor expense. The invention consists in the novel construction and combination of parts, to be more fully described hereinafter, and the novelty of which will be particularly pointed out and distinctly claimed.

• In 1940 flexible metal piping was discussed for use in air ducting
  Bristol, Robert D. "Air duct." U.S. Patent 2,215,318, issued September 17, 1940.
  
  The present invention relates to air ducts, and more particularly to sheet metal air ducts for are to provide an air duct construction comprising standardized elements which may be economically manufactured, conveniently packed for shipment, readily assembled and easily installed;
  
  to provide such an air duct construction the standardized elements of which may be assembled at the place of installation to met virtually any of the innumerable conditions which are encountered in such installations; and, to provide such an air'duct construction the elements of which may be assembled with a minimum of cutting and fitting of the several sheet metal parts.
• Brett, Lewis P. "Air duct construction." U.S. Patent 2,531,349, issued November 21, 1950.
• Clark, Quentin L., and Clifford A. Schroeder. "Flexible insulated duct." U.S. Patent 3,216,459, issued November 9, 1965.
  Since air-conditioning `and heating'system ducting must extend throughout a building and is positioned in attics, walls, and between floors of multi-story buildings, the ducting often passes through extremely restricted spaces.
• Flexduct lawsuit, Richard T.D. Bethea et als, v. Song Hee Hong, et al, filed may 29, 2009, Jackson Tennessee Court of Appeals, dispute involving the contract for sale of a house. A musty odor was associated with mold contaminated flex duct in the building. The ductwork could not be cleaned because of its fragility - an Owl-flex duct product. Sellers (correctly) asserted that the ductwork could not be cleaned. The court finding includes the statement that "OWL FLEX ductwork was uncleanable". The buyers ability to terminate the sales contract was upheld.
• "Design & Installation of Residential Flexible Ductwork Systems", Georgia Department of Community Affairs, 60 Executive Park, NE, Atlanta GA 30329 - (404) 679-4940 - (800) 359-4663 [Also see the installation manuals below at JPL] - original source dca.state.ga.us/development/construction codes/publications/1ONE.pdf
  "1. This information is intended to assist contractors, installers and code officials in the proper design and installation of flexible ductwork systems. The information presented in this document comes primarily from sources in the International Mechanical Code including referenced standards and Georgia Amendments.
  2. It is recommended as a guide that HVAC system documentation, including owner’s manuals, manufacturer’s installation instructions and a sketch of the duct system design that details duct size and approximate duct lengths be provided to the building owner or posted on the air handling unit or furnace. (See sample Duct System Design Sketch). Documentation should also include Manual J calculations."
• "Flexible Duct Performance & Installation Standards", Air Diffusion Council, 1901 N. Roselle Road, Suite 800, Schaumburg, Illinois 60195, Tel: (847) 706-6750, Fax: (847) 706-6751 - Email: info@flexibleduct.org - www.flexibleduct.org/ -
  "The ADC has produced the 4th Edition of the Flexible Duct Performance & Installation Standards (a 28-page manual) for use and reference by designers, architects, engineers, contractors, installers and users for evaluating, selecting, specifying and properly installing flexible duct in heating and air conditioning systems.
  Features covered in depth include: descriptions of typical styles, characteristics and requirements, testing, listing, reporting, certifying, packaging and product marking.
  Guidelines for proper installation are treated and illustrated in depth, featuring connections, splices and proper support methods for flexible duct. A single and uniform method of making end connections and splices is graphically presented for both non-metallic and metallic with plain ends."
  The printed manual is available in English only. Downloadable PDF is available in English and Spanish. 
• Owens Corning Duct Solutions - www.owenscorning.com/ductsolutions/ - provides current HVAC ductwork and duct insulating product descriptions and a dealer locator. Owens Corning Insulating Systems, LLC, One Owens Corning Parkway, Toledo, OH 43659 1-800-GET-PINK™
• "Flexible Duct Media Fiberglas™ Insulation, Product Data Sheet", Owens Corning - see owenscorning.com/quietzone/pdfs/QZFlexible_DataSheet.pdf
  "Owens Corning Flexible Duct Media Insulation is a lightweight, flexible, resilient thermal and acoustical insulation made of inorganic glass fibers bonded with a thermosetting resin."
• "Flexible Duct Performance and Installation Standards", (3rd ed.) – Air Diffusion Council, 1901 N. Roselle Road, Suite 800, Schaumburg, Illinois 60195, Tel: (847) 706-6750 - Fax: (847) 706-6751 email: Email: info@flexibleduct.org
• HVAC Duct Construction Standards—Metal and Flexible (1995 ed.) – Sheet Metal and Air Conditioning Contractors’ National Association, Inc. (SMACNA)
• J.P. Lamborn Co., 559-650-2120 / fax 559-650-2112, email: cuserv@jplflex.com - original source for the air duct installation manuals below - http://www.jplflex.com/featured/instructions.asp - note that these FlexDuct installation guides provided by JP Lamborn Co. originate with the Air Diffusion Council - referenced above.
  Flexible air duct Installation Instructions for Air Ducts & Connectors without fittings
  Flexduct Installation Instructions for Flexible Air Ducts & Connectors with fittings
  Flex duct Installation Instructions for Flex Ducts & Connections using mastic
  "Originally founded in 1961, JP Lamborn Co. has grown to become one of the largest producers of insulated flexible duct in the country. With 4 state of the art manufacturing plants strategically positioned across the USA in order to serve a growing national distributor base. The company prides itself in delivering quality, service, innovations and competitive pricing to customers it serves."
• Plate Glass Company, Pittsburgh, Pa., Filed Febl?, 1963., Sel- N0- 257,196
  
  ... a corporation of [?] and around numerous corners and bends. Thus, for installation purposes, it is often desirable to have a flexible duct which can be readily passed through restricted spaces ....
• Koerber Marvin A, Richitelli Charles G, "Stretchable reinforced wrapper for insulated flexible duct." U.S. Patent 3,885,593, issued May 27, 1975.
• Kutnyak TA, Koerber MA, inventors; Automation Industries, Inc., assignee.
  
  A stretchable but reinforced wrapper or moisture and air barrier is used in the fabrication of insulated flexible duct for air conditioning, heating, and ventilating systems.
  
  The wrapper is a laminate of one or more films having an inherent stretch or elongation characteristic in both axial and bi-axial directions, and a reinforcing material of fabric or fiber for reinforcing the film layer or layers while still allowing bi-axial stretch or elongation of the wrapper and duct.

• Thomas A. Kutnyak, Marvin A. Koerber, "Reinforced flexible duct with integral molded liner." United States patent US 4,196,755. 1980 Apr 8.
  
  The reinforced flexible duct consists of a single- or double-ply reinforcing fabric, a wire helix, and a continuous extruded liner.
  
  The fabric, wire helix, and extruded liner are continuously helically wound on a mandrel. The freshly extruded liner adheres to itself, to the helically wound wire, and to the reinforcing fabric to form a continuous reinforced flexible duct. Optionally, a narrower continuously extruded and wound scuff strip can be wound over the wire helix.

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