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Ventilation Catalogue

Ventilation Introduction

What Affects Fan Performance?

Simple facts:

1. Fan size (i.e. diameter of impeller & outlet)
2. Duct and the way it is installed

Smaller duct = greater resistance to airflow.
More bends = greater resistance to airflow.
Longer duct runs = increasingly reduced airflow.

Wrinkled ducting causes turbulence and reduces airflow

Wrinkdled Duct Airflow Diagram

Smoother, extended ducting allows smooth, increased airflow

Smooth Duct Airflow Diagram

 ALUDUCT flexible ducting retains its stretched-out shape (for smooth airflow) far better than most competitive products. Many competitive ducts tend to shrink back on themselves, wrinkling the duct fabric.

3. Fan type

Centrifugal Flow:

Pressure developing fans which achieve good flow against the resistance created in a ducted system.
Particularly useful in venting areas like internal bathrooms/ laundries, multi-room extraction systems, heat-transfer systems, etc.

Mix Flow
Powerful in-duct mounted fans, designed for applications that require high air flows, with low relative noise.

Axial Flow:
Suitable for wall, window and roof applications where they can extract directly to the outside. Short duct runs are an option but the length of duct should be limited.

  • 100mm dia : 2-3m length
  • 125mm dia : 3-4m length
  • 150mm dia : 4-5m length

Compare Centrifugal Against Axial Fan Performance:

Fan Performance Graph


Fan Performance Graph