2011KOERBER Recommended Practices-Flexible Duct RE NE

7/29/2019 2011KOERBER Recommended Practices-Flexible Duct RE NE

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Recommended Practices

for Properly InstallingFlexible Duct

Presented to

HVACR & Mechanical Instructor Workshop

by

ATCO Rubber Products, Inc.

and the

Air Diffusion Council

March 23, 2011


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Air Diffusion Council

19 Active Members that manufacture flexible ducting inthe US & Canada.

50+ Associate Members that supply materials to the

flexible duct and HVAC industry. 30+ years promoting and furthering the interest of the

general public in the areas of safety, quality, efficiency,and energy conservation.


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Mission Statement of The Air Diffusion Council

The purpose for which the Air Diffusion Council was formed, as stated in its Certification ofIncorporation, is to promote and further the interests of manufacturers of air distributionequipment, more specifically, flexible air ducts and related products, and the interests of the

general public in the areas of safety, quality, efficiency and energy conservation, and to this end,

develop programs approved and supported by the membership that legally promote and further

these interests, such as:

To encourage, assist and support the maintenance and development of credible and effective industry standards

for the installation, use and performance of flexible duct products; to promote the use of those standards by

various code bodies, government agencies; architects, engineers, heating and air conditioning contractors, etc. so

that the best interests of the public may be served.

To collect and disseminate lawful information of value to members of the Council, the general public and

others and to act as a clearing house for all such information, as well as providing a means by which theinterests of the individual members of the Council can be protected, defended, supported more vigorously and

effectively in legal association with others who share those interests.

ADC Bylaws, Article 1, Section 2 (1996)


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ADCFlexible Duct Performance &

Installation Standards(5thEdition)

The Greenbook of

Flex

Provides information about

Characteristics of flexible duct

Testing, Listing, Reporting,

and Certifying

Installation Requirements

Typical Accessories

General Commentary


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Flexible Duct General Information

Available R-Values R 4.2

R 6.0

R 8.0

Packaged in Compressed FormCarton

BagDiameter Range

2 12 (in 1 increments)

14 22 (in 2 increments)

Standard Length 25 Linear Feet


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Flexible Duct Types

(Non-Metallic Ducts)

Insulated

Non Porous Inner Core

Various types of OuterVapor Barriers

Insulated

Perforated Porous Inner Core

Various types of OuterVapor Barriers

Uninsulated


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(Metallic Ducts)

Insulated

Metallic Inner Core

Various types of Outer Vapor Barriers

Uninsulated

Flexible Duct Types


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UL ListedAir DuctNo Length Limitations -

Identified by a Square or Rectangular shaped UL Label

that states UL Listed Air Duct

UL ListedAirConnector

Length restricted to 14 feet maximum -

Identified by a Round Shaped UL Label

that states UL Listed Air Connector,

Not for use in lengths greater than 14feet

How To Identify the Duct

Tested to all UL tests

Limited UL testing


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What makes a good flexible duct installation?

Design the flexible duct system per the requirementsof ACCA Manual D.

Use the flexible duct manufacturers air friction loss

data to size the ducts whenever possible, otherwiseuse the chart in ACCA Manual D.

Use the minimum length of flexible ducting neededto make the connections (Install fully extended).

Keep bends greater than or equal to 1 duct diameter.Minimize sagging and snaking of the duct runs.

Properly seal the flexible duct connections.

Properly support the flexible ducting.

Key Points -


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Key Point #1

Design the flexible duct systemper the requirements of ACCA

Manual D.


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Typical Supply & Return System(Uses Flex Duct & Duct Board Mixing Boxes)

From ACCA Manual D


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Representative Laboratory Test Set-Up Demo

Represents a typical up-flow supply system for an approximate 1100 ft2 dwelling sized following the proceduresin ACCA Manual D. Actual delivery was measured using an ALNOR Balometer.


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Use the flexible duct manufacturers air

friction loss data to size the ductswhenever possible, otherwise use thechart in ACCA Manual D.

Key Point #2


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Typical Duct Air Friction Calculator

250 CFM at 0.2 WC/100

140 CFM = 400 FPM in 8 Duct


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TypicalAir

FrictionLossChart


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Use the minimum length of flexibleduct needed to make the connections.

Install ducts extended to their fullestlength without compression.

When in doubt, stretchhh ittt outtt

Key Point #3


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Longitudinal Compression

of Flexible Duct

Compression causes increased pressuredrop:

15% = approximate 2 times30% = approximate 4 times45% = approximate 6 to 8 times

The moral of the story:

Ducts should be fully extended beforeand during installation.

System has optimum air flow- Minimizes pressure drop- Maximizes savings


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Goals:

1. Make it easy for the air to change direction.

2. Reduce overall equivalent feet of the duct run.

Key Point #4

Keep bends greaterthan or equal to one(1) duct diameter.

Minimize sagging andsnaking of the duct

runs.


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90 = 20 equiv. ft.

180 offset = 40 equiv. ft.

45 = 10 equiv. ft.

So howdo bends actually affect the air flow?


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Examples

If duct is 8 feet long then the totalequivalent length = 28 feet.

For this installation the totalequivalent length is nearlytwice at approximately 50 feet.

Entrance & exit losses intentionally ignored for thisdemonstration.


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The total pressure drop for any duct run equals the sum of the fitting (orbend) pressure drops and the pressure drop of the straight duct section.

Entrance fitting = 35 ft.Total duct length = 14 ft.2 x 45 bends (2 x 10) = 20 ft.1 x 90 bend (1 x 20) = 20 ft.Exit fitting = 35 ft.

Total Equivalent Length = 124 ft.


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Properly seal the flexible duct connections.

Goals:

1. Do we really need to cool the attic or the crawl space?

Key Point #5


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Proper Flexible Duct Connections

Sleeves used to connect 2 flex duct piecestogether shall be a minimum of 4 inchesin length and beaded on each end.

For non-metallic ducts, fittings shall be

beaded and have a minimum of 2 inchescollar length.

Use tapes or mastics listed to the UL181B Standard and marked UL181B-FX for tape and UL181B-M for mastic.

If non-metallic straps are used, the straps should be listed to the UL181BStandard and marked UL181B-C. Maximum pressure is limited to 6 inchesW.C. with non-metallic straps.


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or

The rightway to getfrom here to there!!!!!!!


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Installation Tools& Materials

Tape (UL 181B-FX listed & labeled) Mastic (UL 181B-M listed & labeled)

Non-Metallic (Plastic) Clamps (UL181B-C listed & labeled)

Metallic clamps (worm-gear type)

Sheet metal connecting collar(minimum 4 length with beads eachend)

Sheet metal screws (ONLY Used WithMetallic Inner Cores)

Duct Hanging Material (Straps /Webbing)1-1/2 minimum width

Duct Cutting Tools (Knife, scissors,wire cutters, etc)

Duct Clamp Tensioning Tool


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Using tape and fasteners to make connection

Cut completely through duct and wire

Fold back vapor barrier and insulation

Slide 1 of core over fitting and bead Seal core to collar with 2 wraps of ducttape

Secure connection with clamp placedover the core and tape, past the bead

Pull vapor barrier and insulation backover the core

Tape barrier with 2 wraps of duct tape

Flexible Duct Connection

(Non-Metallic)


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Using tape and fasteners to make splice

Flexible Duct Splice

(Non-Metallic)


Fold back vapor barrier and insulation onboth ends

Slide 1 of each core over connectingcollar and beads

Seal cores to collar with 2 wraps of ducttape

Secure each connection with clampplaced over the core and tape, past thebead

Pull vapor barrier and insulation backover the core and overlap



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(Non-Metallic)



Apply mastic uniformly to the outsidesurface of collar

Slide 1 of core over collar and past thebead

Secure connection with clamp placed

over the core and past the bead Pull vapor barrier and insulation back

over the core and fitting


Using mastic and fasteners to make connection


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(Non-Metallic)


Fold back vapor barrier and insulationon both ends

Apply mastic uniformly to both ends ofthe connecting collar

Slide 1 of each core over connectingcollar and beads

Secure each connection with clamp

placed over the core, past the beads Pull vapor barrier and insulation back

over the core and overlap


Using mastic and fasteners to make splice


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Using tape or mastic and screws to make a connection


(Metallic)

Cut completely through duct and trimedge


When using mastic, apply uniformly to

collar Slide 1 of core over fitting

Secure connection with #8 sheet metalscrews spaced equally aroundcircumference. Use 3 screws fordiameters under 12 and 5 for diameters

12 and over When using tape (press. < 4), seal coreto collar with 2 wraps of duct tape

Pull vapor barrier and insulation backover the core



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Using tape or mastic and sheet metal screws to make splice


(Metallic)

Cut completely through duct and trimedge

Fold back vapor barrier and insulationon both ends

When using mastic, apply uniformlyboth ends of the connecting collar

Slide 1 of core over connecting collar

Secure cores with #8 sheet metal screwsspaced equally around circumference.Use 3 screws for diameters under 12

and 5 for diameters 12 and over When using tape (press.


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Properly support the flexible ducting.

Goals:

1. Never use wire or other materials less than 1-1/2

2. Minimal compression of insulation = better R-Value3. Less sag orsnakingof duct = better air flow

Key Point #6


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What material should I use to support flexible duct?

Per NFPA 90A and 90B, supplementary material used with air ducts shall meetthe requirements of Class 1 when tested to UL 723 (Surface Burn

Characteristic Testing), i.e. 25 Flame Spread & 50 smoke developed maximum.

Per ADC, any strapping material in contact with the flexible duct shall be 1-1/2inch wide minimum and be applied at intervals not to exceed 4 feet (6 feet forvertical supports). Sag should not exceed inch per foot of support spacing.


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Additional Points on Supporting Flex Duct

Ceiling joists or trusssupports used to supportflexible duct

Added supports before and after tight bends Added support to avoid damage by fitting


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Select the proper duct R-value for the job & the codes!

R-4.2

R-6.0

R-8.0Thermal Performance

3rd

Party Verification


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- 30% - 47%


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1 2 3

4 5 6

7 8 9

* 0 #


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The End

VisitADC at www.flexibleduct.org

VisitATCO at www.atcoflex.com

2011KOERBER Recommended Practices-Flexible Duct RE NE

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