Dampers

Dampers help HVAC professionals, ventilation installers, and facility teams manage airflow in supply, exhaust, and ductwork systems. This category includes motorized volume control and shut-off dampers, manual iris dampers for airflow adjustment and measurement, horizontal-mount backdraft dampers for exhaust applications, and fixed non-vented roof curb dampers for roof-mounted ventilation component installations.

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Helpful Buying Guide

Dampers for HVAC, Ventilation, and Ductwork Systems

Dampers control, balance, and shut off airflow in supply, exhaust, and ductwork installations. Whether you need motorized volume control, simple two-position shut-off, manual balancing, or backdraft prevention, choosing the right damper type for your application and mounting location is the fastest path to a reliable installation.

Visual Guide

Popular examples in this category

36-Inch Aluminum Flanged Motorized Volume Control Damper36-Inch Aluminum Flanged Motorized Volume Control DamperWBB77153842-Inch Aluminum Flanged Motorized Damper42-Inch Aluminum Flanged Motorized DamperWBB77154216-Inch Aluminum Hat Channel Motorized Damper16-Inch Aluminum Hat Channel Motorized DamperWBB7715648-Inch Manual Iris Damper8-Inch Manual Iris DamperWBB2110237
What These Products Are For

Managing Airflow in HVAC and Ventilation Systems

Dampers regulate, balance, and isolate airflow in supply and exhaust ductwork, rooftop ventilation, and wall or curb-mounted applications. They are used by HVAC technicians, ventilation installers, and facility maintenance teams to control volume, prevent backdraft, and enable airflow measurement.

How To Choose

Start With Airflow Role and Mounting Location

Identify whether the damper controls supply or exhaust airflow, requires motorized or manual operation, and where it mounts—ductwork, wall, curb, or horizontal exhaust outlet. These three factors narrow your selection before you consider blade type, voltage, or sizing.

Common Applications

Where Dampers Are Typically Installed

Common installations include rooftop unit curb mounts, inline duct balancing, horizontal exhaust fan outlets, and two-position zone control in commercial HVAC. Manual iris dampers suit test-and-balance work, while motorized models serve automated or scheduled airflow control.

Additional Information

Features That Affect Performance and Installation

Look for blade seals on motorized models to reduce leakage, integrated end switches for control feedback, and spring-return mechanisms for fail-safe positioning. Fixed test points on iris dampers simplify commissioning without additional fittings or drilling.

Power-Open / Spring-CloseMotorized Volume Control Operation

Motorized volume control dampers use parallel blades with a power-open, spring-close mechanism, providing a fail-safe return to closed if power is interrupted.

24VShut-Off Damper Control Voltage

The motorized shut-off damper operates at 24V, opening when energized and returning to the normally closed position automatically when power is removed.

Fixed Test PointsIris Damper Measurement Feature

Manual iris dampers include fixed test points for airflow measurement during balancing, eliminating the need to drill or add separate fittings to the duct.

Full Aperture OpeningIris Damper Cleaning Access

The iris damper opens to a fully clear aperture, allowing cleaning access through the duct without removing the damper from the system.

Comparison Guide

Damper Types Side by Side

Match your airflow control need to the right damper type before comparing sizes or features.

NeedBest FitWhy It Matters
Continuous motorized airflow control in supply or exhaustMotorized volume control damper (flanged or hat channel)Parallel blades modulate volume; hat channel version adds blade seals and end switch for duct installs
Simple two-position zone control with fail-safe closed24V motorized shut-off damperOpens on power, returns to normally closed automatically—no manual reset needed
Duct airflow balancing and measurement during commissioningManual iris damperFixed test points and full aperture opening simplify test-and-balance work without extra fittings
Preventing reverse airflow on horizontal exhaust fan outletsHorizontal-mount backdraft damperSized to match fan or powered roof ventilator outlet; gravity or pressure closes blades when fan is off
Capping a roof curb for non-vented equipment installationFixed non-vented roof curb damperProvides a sealed base for roof-mounted ventilation components where airflow through the curb is not needed
Planning Guide

Plan the right fit before choosing

Planning Guide

Step 1 — Define the Airflow Function

Determine whether the damper needs to modulate airflow continuously, switch between fully open and fully closed, prevent reverse airflow, or serve as a fixed non-vented cap for a roof curb. Each function maps to a specific damper type, so clarifying this first prevents misapplication.

  • Continuous volume control: motorized volume control damper with parallel blades
  • Two-position on/off control: 24V motorized shut-off damper (power-open, spring-close)
  • Backdraft prevention on horizontal exhaust: horizontal-mount backdraft damper
  • Airflow balancing and measurement: manual iris damper with fixed test points
  • Non-vented roof curb cap: fixed roof curb damper for component installations
Planning Guide

Step 2 — Confirm Mounting Location and Configuration

Mounting location determines which product version you need. Flanged motorized dampers are designed for wall or curb mounting. Hat channel versions of the same motorized models can also be installed directly in ductwork and include blade seals and an end switch. Backdraft dampers are sized to match the fan or powered roof ventilator outlet diameter.

  • Wall or curb mount: choose flanged motorized volume control damper
  • Inline ductwork install: choose hat channel motorized damper with blade seals and end switch
  • Horizontal exhaust fan outlet: match backdraft damper size to fan outlet
  • Roof-mounted equipment base: use fixed non-vented roof curb damper
Planning Guide

Step 3 — Verify Electrical and Control Requirements

Motorized dampers require a power source and, in some cases, control wiring for the end switch or actuator signal. Confirm available voltage, whether spring-return fail-safe operation is required, and whether the control system needs position feedback before ordering.

  • 24V motorized shut-off: opens when powered, returns to normally closed on power loss
  • Motorized volume control: power-open, spring-close operation with parallel blade design
  • End switch models: provide open/closed position feedback to the control system
  • Manual iris dampers: no electrical requirements, adjusted and locked manually
FAQ

Common questions before buying

What is the difference between a motorized volume control damper and a motorized shut-off damper?

A motorized volume control damper modulates airflow continuously using parallel blades and is suited for supply or exhaust systems where you need variable flow. A motorized shut-off damper is a two-position device—it opens when 24V power is applied and returns to fully closed when power is removed. Use the shut-off model when you only need on/off zone control with a fail-safe closed position.

When should I choose a flanged motorized damper versus a hat channel version?

Flanged motorized dampers are designed for wall or curb mounting. Hat channel versions are built for the same volume control function but can also be installed directly in ductwork. Hat channel models also include blade seals to reduce leakage and an integrated end switch for position feedback to the control system.

How do I size a backdraft damper for a horizontal exhaust application?

Match the backdraft damper diameter or dimensions to the outlet size of the exhaust fan or powered roof ventilator it will serve. The damper should correspond to the fan's discharge collar size, not the duct diameter upstream, to ensure proper blade operation and an airtight seal when the fan is off.

Can a manual iris damper be used for both balancing and airflow measurement?

Yes. Manual iris dampers include fixed test points that allow airflow measurement with a manometer or pitot tube without drilling the duct. The iris mechanism also opens to a full, unobstructed aperture for cleaning access. Once balanced, the iris position is locked in place to maintain the set airflow rate.

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