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Ducts are properly insulated and supported without compressing the insulation

Ducts are insulated but strapping is compressing the insulation therefore reducing the R-value

Duct and HVAC Insulation

Author(s)

North American Insulation Manufacturers Association

Organization(s)

NAIMA

Publication Date

January, 2010

Information sheet with HVAC duct insulation, testing, maintenance and performance information.

Sealed and Insulated Metal Ducts

Guide describing how to air seal and insulate metal ducts.

Sealed and Insulated Flex Ducts

Guide describing how to air seal and insulate flex ducts.

Ducts Buried in Attic Insulation and Encapsulated

Guide describing approaches to burying and encapsulating ducts in unconditioned attics to increase the overall R-value of duct insulation.

Air seal and insulate flex ducts

Publication Date

Fri, 10/28/2011 - 12:00

Duct insulation is installed over boot

Insulation does not cover boot and is not sealed

Duct is located in unconditioned space and is not insulated

Sealed and Insulated Fiber Board Ducts

Guide describing how to air seal and insulate fiber board ducts.

Insulation does not cover boot and is not sealed

No insulation installed in cavity and not air sealed

Duct is located in unconditioned space and is properly insulated

Measure Guideline: Sealing and Insulating Ducts in Existing Homes

Author(s)

Aldrich Robb,

Puttagunta Srikanth

Organization(s)

Consortium for Advanced Residential Buildings,

CARB,

National Renewable Energy Laboratory,

NREL,

Steven Winter Associates,

SWA

Publication Date

December, 2011

Report describing the sealing and insulating of HVAC duct systems in existing homes.

Prescriptive Path: Supply ducts in unconditioned attic have insulation ≥ R-8. Performance Path: Supply ducts in unconditioned attic have insulation ≥ R-6

Pull the insulation and outer liner of the flex duct over the collar to come in full contact with the liner and insulation of the trunk line or fitting and tape in place

Boot has been covered with insulation and sealed with mastic

Publication Date

Fri, 10/28/2011 - 12:00

Inadequate amount of insulation installed with compression, misalignment, and voids

Trunk to duct connections are properly insulated and have been sealed with mastic

Wrong - Flex duct resting on floor compressing insulation and causing condensation

Seal all joints and seams in the metal ductwork with mastic before installing insulation

Cleaning Fibrous Glass Insulated Duct (Ductboard / Duct Board) Systems - Recommended Practices

Author(s)

North American Insulation Manufacturers Association

Organization(s)

NAIMA

Publication Date

June, 2019

Manual showing duct cleaning contractors how to identify the different types of insulated air ducts, how to open each type for access by cleaning equipment and personnel, how to close and seal openings after cleaning.

Wrong - Duct insulation and vapor barrier do not cover all of the flex duct.

Publication Date

Fri, 12/07/2018 - 12:00

Wrong - Flex duct insulation is overly compressed in 3 ways; Zip-tie fastener is over the insualtion not under the insulation at the duct boot collar, duct turning radius is too tight, and support strap is too tight.

Publication Date

Sat, 01/19/2019 - 12:00

Right – Flex ducts are properly supported with straps that don’t pinch the insulation; closed-cell spray foam will be applied to the underside of the roof deck of this hot-humid climate home to provide an insulated attic space for the HVAC ducts.

Publication Date

Thu, 09/30/2021 - 12:00

Cavity used for return is not insulated and is not air sealed, which will pull in air from outside

Wrong- A tie strap should not be used over the duct outer liner because it can compress the insulation. Tuck in the fibrous insulation and seal the outer liner to the connecting duct with mastic or foil tape (Steven Winter Associates 2013).

All other supply ducts and all return ducts in unconditioned space have insulation ≥ R-6

Publication Date

Fri, 10/28/2011 - 12:00

A nylon draw band and tensioning tool are used to secure the inner coil of the pre-insulated flexible duct

Publication Date

Wed, 11/21/2012 - 12:00

A nylon draw band and tensioning tool are used to secure the inner liner of the pre-insulated flexible duct

When wrapping metal ducts with insulation allow two inches of overlap and staple along the seam with outward clinching staples

If HVAC duct must be installed in an exterior wall, separate it from the exterior with at least R-6 of continuous rigid insulation

Right – Rigid foam is installed behind HVAC ducts to provide additional insulation to the ducts which are installed within the conditioned space.

Publication Date

Mon, 09/30/2019 - 12:00

Wrong: open wall cavity connected to this return air plenum is allowing cellulose attic insulation to be pulled into the furnace

Publication Date

Sun, 06/01/2014 - 12:00

A ducted central return brings air from central return registers back to the air handler through insulated, air-sealed ducts

Publication Date

Thu, 03/09/2017 - 12:00

To attach the flex duct to a main trunk duct or any other connection, the flex duct is pulled over the connecting collar at least 2 inches past the raised bead, then the insulation is pulled back

Wrong – These flex ducts are pulled taut, which is correct but they are inadequately supported with straps that are spaced too far apart and are too tight causing pinching of the insulation and turns are sharp rather than gradual.

HVAC ducts, cavities used as ducts, and combustion inlets and outlets may pass perpendicularly through exterior walls but shall not be run within exterior walls unless at least R-6 continuous insulation is provided on exterior side of the cavity

Right - The precast insulated concrete walls of the basement provide a conditioned space for the high-efficiency (18 SEER, 9.5 HSPF) air-source heat pump, with its variable-speed fan, five-stage compressor, and MERV 11 filter.

Ducts in Raised Ceiling Sections

Guide describing method for designing and installing ducts in a raised ceiling chase.

Encapsulated Ducts

Guide that illustrates how and when to encapsulate ductwork in unconditioned attics, increases the R-value of duct insulation, mitigating condensation issues and reducing air leakage.

Support at Intervals for Flex Ducts

Guide describing how to hang ducts with supporting straps or saddles to adequately support ducts so they do not sag and are not pinched or compressed in a manner that would cause damage to the ducts, the duct insulation, or the duct air barrier covering.

Sufficient Cavity Space for Flex Ducts

This measure guide describes how to correctly install ducts, ensuring enough cavity space to avoid compression.

Burried and encapsulated ducts in a ceiling plane

Publication Date

Fri, 02/01/2013 - 12:00

HVAC Ducts Shall Not Be Run within Exterior Walls

Guide describing the use of building cavities as supply or return ducts.

Show Home Targets Energy Efficiency in Hot-Humid Climates

Author(s)

U.S. Department of Energy

Organization(s)

DOE

Publication Date

November, 2004

Case study describing the New American Home project.

Measure Guideline: Reducing Thermal Losses and Gains With Buried and Encapsulated Ducts in Hot-Humid Climates

Author(s)

Mantha Pallavi,

Zoeller William,

Shapiro Carl

Organization(s)

Consortium for Advanced Residential Buildings,

CARB,

Steven Winter Associates,

SWA

Publication Date

August, 2013

Document covering the technical aspects of buried and insulated ducts (BEDs), as well as the advantages, disadvantages, and risks of BEDs compared to alternative strategies.

New Whole-House Solutions Case Study: Lancaster Live/Work Townhome Prototype

Author(s)

Building Science Corporation

Organization(s)

BSC

Publication Date

April, 2010

Case study describing a building project in the marine climate.

No Excessive Coiled or Looped Flex Ducts

Guide outlining how to correctly install flex ducts without excessive coils or loops.

Boot is uninsulated

Publication Date

Fri, 10/28/2011 - 12:00

Duct work is uninsulated and not sealed at seams

HVAC duct layout

No Kinks or Sharp Bends in Flex Duct Installation

Guide outlining how to correctly install flex ducts without kinks or sharp bends.

Seams are being properly sealed with mastic and mesh tape

Trunk to duct connections are only mechanically fastened and not sealed

Assembled section of fiber board duct

Publication Date

Fri, 01/11/2013 - 12:00

Use only Underwriters Laboratory UL-181 approved tape

The tape is covered with mastic to ensure an airtight seal between the duct and the fitting

Fiber board sheets are available with pre-cut shiplapped ends

After securing the inner coil, cover the draw band and the seam with a generous amount of mastic

Collars that are specifically made for flexible duct have a raised bead to prevent the duct from slipping off

Fiberglass duct board typically comes in sheets 4 foot wide by 10 foot long

Two pieces of flex duct are spliced together with a metal sleeve, nylon draw bands, mastic, metal tape, and more mastic

Seal seams in fiber board ducts with out-clinching staples, UL-181A-approved tape, and mastic

Hand tools for cutting fiber board sheets include a knife, straight edge, and color-coded edge-cutting tools

Right – R-25 of open-cell spray foam lines this new home’s attic ceiling, to protect HVAC ducts from heat and cold.

Right - Open-cell polyurethane spray foam to R-28 on underside of roof turns new attic into conditioned space for HVAC.

No Ducts or Air Handlers Located in Garage

Guide describing how to design HVAC systems to be located within the conditioned space of the home, either in a utility closet or in an air sealed conditioned attic, basement, or crawl space.

Cut fiber board with a red V-groove tool and a gray shiplap tool to create mitered corners and a shiplapped edge for duct sections

New Whole-House Solutions Case Study: Pine Mountain Builders, Pine Mountain, Georgia

Author(s)

Pacific Northwest National Laboratory

Organization(s)

PNNL

Publication Date

January, 2013

Case study describing a builder in Georgia that designs energy-efficient homes for a green community, yielding homes with HERS scores as lowas 59 and electric bills as low as $50 a month.

Example of an HVAC installer’s balancing report form

Publication Date

Sun, 05/01/2011 - 12:00

Energy Code - Module 7: Ducts, HVAC, Hot Water, and Lighting

Author(s)

Nebbia

Organization(s)

Newport Partners

Publication Date

January, 2022

Webinar that will explain mandatory and prescriptive requirements related to duct installation, insulation, sealing, and testing, as well as requirements for heating, cooling, and hot water systems and controls.