Fan Engineering Guides

Video-led explanations of fan operation, selection, testing and system behavior for HVAC and equipment engineers.

Testing the signal on an EC fan not responding to its controller
By longwell / September 10, 2026 / Fan Engineering Guides

Why Is My EC Fan Not Responding to Control Signal?

A fan that runs at one speed regardless of the signal usually has a wi...

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Blower wheel with uneven dirt build-up causing imbalance
By longwell / September 10, 2026 / Fan Engineering Guides

Blower Wheel Out of Balance: Symptoms & Fix

An unbalanced wheel announces itself through vibration at exactly one ...

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Engineer listening to identify whistling and humming fan noise
By longwell / September 10, 2026 / Fan Engineering Guides

Whistling / Humming Fan Noise: Diagnose the Sound

Different fan noises come from different physics. A whistle is usually...

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Axial fan blade pitch and angle of attack shown on a hub
By longwell / September 10, 2026 / Fan Engineering Guides

Fan Blade Pitch & Angle of Attack Explained

Pitch is the single strongest lever on axial fan performance. Increase...

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Airfoil impellers with aerofoil section blades in a centrifugal fan
By longwell / September 10, 2026 / Fan Engineering Guides

Why Airfoil Impellers Are the Most Efficient

Airfoil blades reach the highest static efficiency of any centrifugal ...

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Volute cutoff clearance shown between the scroll tongue and the wheel
By longwell / September 10, 2026 / Fan Engineering Guides

Volute / Scroll Housing & Cutoff Design

The scroll does half the work in a centrifugal fan, and the cut-off de...

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Fan inlet cone and venturi ring guiding air into an impeller
By longwell / September 10, 2026 / Fan Engineering Guides

Inlet Cone & Venturi: Small Part, Big Efficiency

The inlet cone is a cheap pressing that decides how cleanly air enters...

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Specific speed chart mapping fan types against duty ranges
By longwell / September 9, 2026 / Fan Engineering Guides

Specific Speed: How Engineers Pick a Fan Type

Specific speed collapses airflow, pressure and rotational speed into o...

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Fan inlet with a bend close to it causing system effect losses
By longwell / September 9, 2026 / Fan Engineering Guides

System Effect: The Hidden Efficiency Killer

A fan tested in a laboratory rarely meets its curve on site, and syste...

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Sound power measurement of a fan in an acoustic test chamber
By longwell / September 9, 2026 / Fan Engineering Guides

Sound Power vs Sound Pressure (dB Deep Dive)

Sound power belongs to the fan. Sound pressure belongs to the room. Co...

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