Linear Slot Air Diffuser

What is a Linear Air Grille? Structure and Working Principle

A Linear Air Grille (Linear Diffuser) is a narrow, elongated slot-type air terminal used for air supply and return in HVAC systems. It provides smooth, uniform air distribution with high aesthetic value. Linear grilles are typically installed on ceilings, walls, or technical partitions. Unlike conventional grilles, the linear design forms a continuous air slot, ensuring even airflow distribution while delivering a modern architectural appearance.

Structure of a Linear Air Grille

A standard Linear grille consists of four main components:

1. Frame: Made of powder-coated or anodized extruded aluminum, providing rigidity, corrosion resistance, and durability in humid HVAC environments.
2. Directional Blades: Installed inside the slot, adjustable ±15–30° to control airflow direction, balance temperature, and regulate air distribution.
3. Air Slots: Available in single-slot, double-slot, or triple-slot configurations depending on airflow and design requirements.
4. Neck & Plenum Box: Connects to flexible ducting; can integrate a volume damper for airflow balancing and performance optimization.

Working Principle

Conditioned air is delivered through the duct into the plenum box and then discharged through the narrow linear slots. The air spreads along the ceiling surface and rapidly mixes with room air, resulting in:

• Low air velocity

• Low noise level

• High thermal diffusion efficiency

These characteristics make Linear diffusers ideal for modern HVAC applications requiring both comfort and aesthetics.

Types of Linear Air Grilles

1. By Number of Slots

• Single-slot Linear – Suitable for narrow spaces, low ceilings, and low airflow (corridors, small offices).

• Double / Triple-slot Linear – Higher airflow and wider distribution (offices, malls, public areas).

• Continuous multi-slot Linear – Long continuous air strip for premium architectural designs.

2. By Function

• Supply Linear Diffuser – Includes adjustable blades for directional airflow control and draft prevention.

• Return Linear Grille – No directional blades; larger free area for efficient air return and pressure balance.

3. By Material

• Powder-coated aluminum – Most common, lightweight, corrosion-resistant.

• Stainless steel (Inox) – For high-humidity or hygienic environments (cleanrooms, hospitals).

• PVC engineering plastic – Lower cost, good insulation, but lower mechanical strength.

4. By Installation Location

• Ceiling installation (most common)

• Wall or floor installation (when ceiling mounting is not feasible)

Key Advantages

1. Uniform Air Distribution – Low Noise
Continuous slot design ensures even airflow, minimizes cold drafts, and meets NC25–NC30 noise standards for offices and premium spaces.

2. High Architectural Aesthetics
Slim aluminum profile allows continuous alignment, creating a seamless modern ceiling or wall finish.

3. Flexible Airflow Control
Adjustable blades ±15–30° enable precise airflow direction and pressure balancing. Can integrate volume dampers for airflow regulation.

4. Durable and Easy Maintenance
Anodized or powder-coated aluminum resists corrosion and deformation. Removable structure simplifies cleaning and servicing.

Applications in HVAC Systems

Office Buildings & Commercial Centers
Used with VRV/VRF or AHU systems to provide quiet, uniform airflow and improved thermal comfort.

Hotels, Restaurants, Showrooms
Continuous slot design enhances interior aesthetics while delivering smooth, draft-free air distribution.

Hospitals, Cleanrooms, Data Centers
Precise airflow control supports pressure regulation and air quality management when combined with HEPA filtration and dampers.

Industrial Facilities
Can be installed in parallel continuous runs for large-area airflow distribution with long-term durability.

Technical Standards and Installation Notes

Typical Performance Range

• Airflow rate: 60–250 m³/h per meter length (depending on slot width 12–25 mm and number of slots)

• Recommended air velocity: 2.0–3.5 m/s

• Static pressure: 20–40 Pa

• Noise level: ≤ NC30 (office), ≤ NC35–40 (commercial)

Installation Guidelines

• Install at least 300–500 mm from walls for uniform air distribution.

• Ensure airtight flexible duct connection to prevent pressure loss.

• Use plenum box with volume damper for airflow balancing.

• Measure airflow with anemometer after installation for proper adjustment.

Common Installation Errors

• Incorrect airflow direction

• Incorrect ceiling cut-out size

• No airflow balancing → noise or weak airflow

• Lack of cleaning before operation → dust buildup

Proper installation ensures optimal HVAC performance, comfort, and long service life.

G-Sora Linear Air Grille for HVAC

G-Sora is a leading manufacturer and supplier of HVAC accessories in Vietnam, providing high-quality Linear air grilles for M&E contractors, consultants, and project owners nationwide. With extensive experience in ventilation and air-conditioning systems, G-Sora delivers reliable, high-performance air distribution solutions for modern buildings.