Rigid fiberglass HVAC duct board air handler (C) Daniel Friedman Rigid Insulating Board HVAC Ducts

  • FIBERGLASS DUCT, RIGID CONSTRUCTION - CONTENTS: Rigid insulating board to build air conditioning or heating ducts. Tools used to construct ductwork. How to use fiberglass duct board to construct HVAC ductwork. Use of rigid duct board with a thermosiphoning air collector (TAP). Using basement air with a thermo-siphoning air collector system. Solar Age Magazine Articles on Renewable Energy, Energy Savings, Construction Practices
  • POST a QUESTION or READ FAQs about rigid fiberglass duct insulation board

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Fiberglass insulating duct board:

This article discusses the use of rigid insulating board to construct air conditioning and heating system ductwork, and use of rigid ductwork with a thermosiphoning air collector system (TAP).

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Rigid Insulating Board & Fiberglass Air Conditioning & Heating Duct Construction

Exposed fiberglass in ductwork (C) Daniel FriedmanOur page top photograph shows reinforced aluminum foil faced fiberglass duct board used to construct the supply air plenum on a heating system.

The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.

Question: How are Rigid-Insulation Ducts Constructed, What Materials & Tools are Used?

I have heard that rigid insulating board can be used to construct heating ducts (or air conditioning ductwork). Can you provide information about the construction of rigid insulating board ductwork, including duct construction tools, etc.?

Is it reasonable to use rigid duct board with a thermosiphoning air collector (TAP), considering that I desire to move air 12 to 15 feet from the south wall to the middle of a one-story house?

This thermosiphoning air collector plan also includes using air from the basement to enter the cold side of the TAP. -- Byrl Bowman, Kalamazoo, MI

Answer: Fiberglass Duct Board

The product you refer to is fiberglass duct board, available from Certainteed, Knauf, and Owens Corning.

The fiberglass insulating board panels are one-inch in thickness, R-4.3, rigid-fiberglass panels that have a reinforced kraft paper or foil facing on one side. Rigid fiberglass duct board panels can be cut and fitted on site using a utility knife and special grooving tools to make the folds and laps.

The duct board sections are stapled together and sealed using pressure-sensitive aluminum foil tape.

The duct construction hand tools are made by AmCraft, Inc..

To purchase fiberglass insulation duct board materials, check with the larger heating and air-conditioning supply houses in your area, or with a manufacturer's rep.

As for your plan to use a thermosiphoning air collector, it sounds fine, but don't expect much air flow from a thermosiphoning collector if the system is ducted. A fan will be needed.

Technical Opinion About Rigid Fiberglass Ductwork

Foil faced rigid fiberglass duct board has proven an excellent system for constructing air plenums and main trunk lines for duct systems for both heating and air conditioning, and is in popular use across North America as well as in other countries. -- DJ Friedman

Advantages of Rigid Fiberglass Duct Board

  • Rapid, easy, low-cost onsite custom fabrication of ductwork
  • Combination of both duct insulation and a rigid material to form the duct itself
  • Ductwork constructed of this material transmits much less noise than metal ductwork

Disadvantages of Rigid Fiberglass Duct Board

Exposed fiberglass in ductwork (C) Daniel Friedman
  • Cleaning difficulty: When ducts are constructed using board that is foil faced only on the outside, the inner, fiberglass insulation can not be mechanically cleaned without damaging the ducts.

    If the fiberglass is damaged an increased level of release of fiberglass into the building air may be a problem for building occupants.

    also FIBERGLASS FRAGMENT HAZARDS in AIR or DUST for details.
  • Mold growth: In some air conditioning systems (improperly maintained, improper handling of condensate, or location in very humid climates), over-spray of condensate in the air handler or leaks into the ductwork can combine with the collection of organic debris in house dust to support mold growth.

    In some instances problem mold growth may be present in duct work at a significant level, although usually our field investigation finds that there are other more critical mold reservoirs in buildings where mold is detected in the duct system.
    See Mold in Fiberglass Insulation for details.

Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

Original Article

The link to the original Q&A article in PDF form immediately below is preceded by an expanded/updated online version of this article.


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