New Duct Components

Detail ID 5.0104.1
Topic
Forced Air
Subtopic
Duct Installation
Desired Outcome

Efficient, quiet, and optimal air flow, provided through safe, durable, and sealed ducts that do not have visible air leakage @ 25 pascals

SF Single Family Site-Built Housing
MH Manufactured Housing
MF Multifamily Housing

Specifications

  • SF
  • MF
Specification Objective

Select insulation:

with a flame spread and smoke development index of 25/50 when tested in accordance with ASTM E84 or UL 723 and that includes an exterior vapor retarder layer

Select duct materials:

with a flame spread of no more than 25 when tested in accordance with ASTM E84 or UL 723 and that are UL 181, SMACNA, NAIMA approved or conform to ASTM A653

Select durable and safe materials

  • SF
  • MF
Specification Objective

Remove all old ductwork and duct insulation from the premises

Old duct materials disposed of off premises

  • SF
Specification Objective

Design residential duct systems using friction charts and ANSI/ACCA Manual D (Residential Duct Systems) or equivalents

Do not use building cavities as ductwork under any situation

Route ducts so that standard service and repair to the building and its systems does not damage the ducts

Maximize air flow

  • MF
Specification Objective

Design residential duct systems using friction charts, ANSI/ACCA Manual D (Residential Duct Systems), or ASHRAE equivalents

Design commercial duct systems using ANSI/ACCA Manual Q (Low Pressure, Low Velocity Duct System Design), or ASHRAE equivalents

Do not use building cavities as ductwork under any situation

Route ducts so that standard service and repair to the building and its systems does not damage the ducts

Maximize air flow and safeguard indoor air quality

  • SF
Specification Objective

Design supply terminations to be capable of delivering air with the proper speed and throw to cover the entire space they serve and that do not produce noticeable flow noise when system is operating at full speed

Design return grille gross area to be equal to or larger than return box

Appropriate level of air mixing, air flow, and occupant comfort

  • MF
Specification Objective

Design terminations using ANSI/ACCA Manual T (Air Distribution Basics)

Terminations must be capable of delivering air with proper speed and throw of 80-120% of the farthest wall, floor, or ceiling they serve, and must have a noise level less than 30 decibels

Return grille gross area will be equal to or larger than return box

Appropriate level of air mixing, air flow, and occupant comfort

  • SF
  • MF
Specification Objective

During renovation or construction, block registers, grilles, and diffusers with a durable material

Do not use duct system until construction is finished

Protect equipment and ducts from damage and debris collection

  • SF
  • MF
Specification Objective

For exterior ducts (i.e., exposed to outdoors), use duct material that meets the following criteria:

insulation level of R-12 or greater

includes a weatherproof barrier that is resistant to ultraviolet light damage

will not be damaged by weather

Prevent condensation, reduce thermal loss or gain, protected from elements

  • SF
  • MF
Specification Objective

When a 90 degree turn is required in the plenum, use radius elbow fittings or square fittings with turning vanes

Supply plenum must be the same size or larger than the air handler supply opening

If equipment is installed on top of the return plenum, plenum platform must independently support the weight of the equipment

Minimize static pressure and maximize air flow

  • SF
  • MF
Specification Objective

Install reducers between sections of different size ducts in accordance with existing standards based on duct material (e.g., SMACNA, NAIMA)

Minimize static pressure and maximize air flow

  • SF
  • MF
Specification Objective

Install runs as short as possible

Minimize static pressure and maximize air flow

  • SF
  • MF
Specification Objective

Install take-offs onto the trunk in accordance with duct construction standards (SMACNA)

Install take-offs using mechanical fasteners for all applications

Take-offs that create high turbulence will not be used (e.g., elbows with integrated dampers, scoops)

Minimize static pressure and maximize air flow

  • SF
  • MF
Specification Objective

Install flexible duct as straight as possible and fully stretched without unnecessary sagging, crimping, or bends

Do not bend flexible duct more than 45 degrees without using a rigid elbow

Use a rigid connector when joining two pieces of flexible duct together

Minimize static pressure and maximize air flow

  • SF
  • MF
Specification Objective

Use boots with a directional collar (e.g., 45 degree elbow) whenever ducting turns directly after the boot connection

If using straight boots, connect an elbow to the boot before connecting the duct

Do not connect flexible duct directly to a straight boot if it turns more than 15 degrees within 6' of boot connection

Minimize static pressure and maximize air flow

  • SF
  • MF
Specification Objective

Install fire dampers and ductwork in accordance with applicable fire code

Install smoke alarms inside duct plenums that convey more than 2500 cfm

Seal ductwork penetrations through fire rated surfaces according to applicable code requirements for the surface

Meet applicable fire code and provide functional smoke detection

  • SF
  • MF
Specification Objective

Install accessible filter grills that have no air bypass around the filters

Install filter slot covers to prevent return air leakage

Avoid filters with high static pressure drop unless system is designed for them

Protect equipment from dirt and debris and allow proper airflow

  • SF
  • MF
Specification Objective

Room-to-room pressure differences shall not exceed 3 pascals with the air handler running

Install appropriate means of pressure balancing if necessary (e.g., transfer grilles, jumper ducts, individual room returns)

Unrestricted air flow, minimize shell leakage caused by duct system, prevent interference with combustion appliance function

  • SF
  • MF
Specification Objective

Seal all ducts in accordance with SWS Subtopic "Duct Sealing"

Seal ductwork penetrations through interior walls with a durable and compatible sealant (e.g., caulk, silicone)

Visibly sealed ducts and penetrations

  • SF
  • MF
Specification Objective

Fasten duct connections in accordance with SWS detail "Duct Repair: Mechanical Fastening"

Durable duct connection

  • SF
  • MF
Specification Objective

Support ducts in accordance with SWS detail "Duct Repair: Duct Support"

Durably supported ducts

  • SF
  • MF
Specification Objective

Insulated ducts in accordance with SWS Detail "General Duct Insulation"

Properly insulated and condensation resistant ducts

  • SF
  • MF
Specification Objective

Install dampers as close to the trunk as possible and in accessible locations to the fullest extent possible

Volume dampers are accessible after interior finishes are installed

View Sub-Topic:
Duct Installation