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Ducts are properly insulated and supported without compressing the insulation

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

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Duct and HVAC Insulation

Reference

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

Sealed and Insulated Flex Ducts

Guide

Guide describing how to air seal and insulate flex ducts.

Ducts Buried in Attic Insulation

Guide

Guide describing the practice of burying HVAC ducts in loose-fill insulation on the attic floor.

Mechanical Insulation Design Guide - Installation

Reference

Web resource that lays out the pre-work considerations, methods and finishes for installing mechanical insulation.

Ducts Buried in Attic Insulation and Encapsulated

Guide

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

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Duct insulation is installed over boot

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Insulation does not cover boot and is not sealed

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Duct is located in unconditioned space and is not insulated

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Duct is located in unconditioned space and is properly insulated

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

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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

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Exterior Insulation Implications on Heating and Cooling in Cold Climates

Reference

The New York State Energy Research and Development Authority (NYSERDA) is interested in finding cost-effective solutions for deep energy retrofits (DERs) related to exterior wall insulation in a cold climate, with targets of 50% peak load reduction and 50% space conditioning energy savings.

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

Right – Spray foam air seals and insulates the walls including the walls behind the fireplace and covers the underside of the roof deck of this mixed-dry climate home to provide an insulated attic space for HVAC ducts.

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This IR camera image shows an HVAC duct in the attic that may have displaced insulation.

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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).

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

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The pipe insulation on this exterior refrigerant line is intact but significantly degraded from ultraviolet (UV) exposure.

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

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

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Baffles are installed to protect airflow from the soffits to the ridge vents before the ceiling drywall and attic insulation are installed.

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

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

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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

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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

Sealed and Insulated Flex Ducts

Ducts Buried in Attic Insulation

Mechanical Insulation Design Guide - Installation

Ducts Buried in Attic Insulation and Encapsulated

Air seal and insulate flex ducts

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

Duct is located in unconditioned space and is properly insulated

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

Exterior Insulation Implications on Heating and Cooling in Cold Climates

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

Spray foam insulates and air seals the underside of the attic roof and walls.

Right – An insulated space is provided in the home’s attic to house the HVAC equipment.

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

Right – Spray foam air seals and insulates the walls including the walls behind the fireplace and covers the underside of the roof deck of this mixed-dry climate home to provide an insulated attic space for HVAC ducts.

This IR camera image shows an HVAC duct in the attic that may have displaced insulation.

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

The pipe insulation on this exterior refrigerant line is intact but significantly degraded from ultraviolet (UV) exposure.

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

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

Baffles are installed to protect airflow from the soffits to the ridge vents before the ceiling drywall and attic insulation are installed.

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

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

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