The GWDD4520 Aluminium Double Deflection Grille is designed for use in cooling, heating, and ventilation systems. It provides precise directional airflow control through individually adjustable blades and includes a removable core for easy installation, cleaning, and access to dampers. Constructed from durable aluminium, the grille offers long-lasting performance and a professional appearance suitable for a wide range of HVAC applications.
Application
Suitable for both supply and return air in residential, commercial, and industrial HVAC systems. Ideal for situations requiring adjustable airflow direction and straightforward maintenance. Mullions are fitted to grilles where blade lengths exceed 800 mm to ensure rigidity and airflow consistency.
Features / Benefits
- Suitable for cooling, heating, and ventilation applications
- Individually adjustable blades for precise directional airflow control
- Removable core for easy installation, cleaning, and damper access
- Mullions fitted to grilles with blade lengths exceeding 800 mm
- Durable aluminium construction for corrosion resistance and longevity
- Available in a wide range of sizes to suit most system designs
The table below gives the minimum height for a flat ceiling for satisfactory performance, base on the register being mounted between 300 and 600 mm below the ceiling for a range of flows between 3 and 20 metres
| Output Velocity (m/s) | Minimum Ceiling Height in Metres |
| 3 | 4.5 | 6 | 7.5 | 9 | 10.5 | 12 | 15 | 18 |
| 2.0 | 2.4 | 2.7 | 3.0 | 3.3 | 3.7 | 4.0 | 4.3 | 4.6 | 4.9 |
| 2.5 | 2.4 | 2.7 | 3.0 | 3.0 | 3.3 | 3.7 | 4.0 | 4.3 | 4.6 |
| 3.0 | 2.4 | 2.7 | 2.7 | 3.0 | 3.3 | 3.7 | 4.0 | 4.3 | 4.6 |
| 4.0 | 2.4 | 2.7 | 2.7 | 3.0 | 3.3 | 3.3 | 3.7 | 4.0 | 4.3 |
| 5.0 | 2.1 | 2.4 | 2.4 | 2.7 | 3.0 | 3.0 | 3.3 | 3.7 | 4.0 |
| 6.0 | 2.1 | 2.4 | 2.4 | 2.7 | 3.0 | 3.0 | 3.3 | 3.3 | 3.7 |
| 7.0 | 1.8 | 2.1 | 2.4 | 2.7 | 2.7 | 3.0 | 3.0 | 3.3 | 3.3 |
| 8.0 | 1.8 | 1.8 | 2.1 | 2.4 | 2.4 | 2.7 | 2.7 | 3.0 | 3.0 |
| | Throw Range in Metres |
Table 1.
The above figures are for straight blow and 22.5?
For 45? vane setting, deduct 300 mm from ceiling height
| Outlet Velocity (m/s) | Noise Rating (NR) | Typical Applications |
| 2.5 | 25 - 30 | Bedroom, Auditioriums |
| 3.7 | 35 - 40 | Private Office |
| 5.0 | 40 - 45 | General Office |
| 7.5 | 50 - 60 | Light Industrial |
Table 2.
Design NR Values bases on AIRAH DA2, Noise Control
| Air Volume (L/s) | Register Size | 450 x 200 |
| Vane Setting | 0? | 22.5? | 45? |
| 125 | Throw (m) | 6 | 5 | 4 |
| Velocity (m/s) | 2 | 2 | 2.5 |
| Static Pressure (Pa) | 2 | 2.5 | 3 |
| 150 | Throw (m) | 6.5 | 6 | 5 |
| Velocity (m/s) | 2 | 2.5 | 2.5 |
| Static Pressure (Pa) | 2.5 | 3 | 4 |
| 200 | Throw (m) | 9 | 7.5 | 6.5 |
| Velocity (m/s) | 3 | 3 | 3.5 |
| Static Pressure (Pa) | 5 | 6 | 7.5 |
| 250 | Throw (m) | 11 | 9.5 | 8 |
| Velocity (m/s) | 3.5 | 4 | 4.5 |
| Static Pressure (Pa) | 7 | 9.5 | 11.5 |
| 300 | Throw (m) | 13.5 | 11.5 | 9.5 |
| Velocity (m/s) | 4 | 5 | 5.5 |
| Static Pressure (Pa) | 10 | 10 | 16.5 |
| 350 | Throw (m) | 15.5 | 13.5 | 11 |
| Velocity (m/s) | 5 | 5.5 | 6 |
| Static Pressure (Pa) | 13.5 | 18 | 22 |
| 400 | Throw (m) | 17.5 | 15.5 | 12 |
| Velocity (m/s) | 5.5 | 6.5 | 7 |
| Static Pressure (Pa) | 17.5 | 24 | 28 |
| 450 | Throw (m) | 20 | 17 | 14 |
| Velocity (m/s) | 6 | 7.5 | 8 |
| Static Pressure (Pa) | 22 | 30 | 37 |
| 500 | Throw (m) | 22 | 18.5 | 15.5 |
| Velocity (m/s) | 7 | 8 | 9 |
| Static Pressure (Pa) | 23 | 37 | 45 |
| 550 | Throw (m) | 24 | 21 | 17.5 |
| Velocity (m/s) | 7.5 | 9 | 9.5 |
| Static Pressure (Pa) | 32 | 45 | 54 |
| 600 | Throw (m) | 27 | 23 | 19 |
| Velocity (m/s) | 8.5 | 9.5 | 10.5 |
| Static Pressure (Pa) | 39 | 54 | 66 |
Table 3.
Air Volume - Litres per Second (L/s)
Throw (m) is to a terminal velocity of 0.25m/s
Static Pressure - Pascals (Pa)
Core Velocity - Metres per Second (m/s)
