Fan Engineering Guides

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

Shaded-pole motors compared with PSC and BLDC fan motors
By longwell / September 9, 2026 / Fan Engineering Guides

BLDC vs Shaded-Pole vs PSC Motors

Three motor types cover most small fans, and they differ by a factor o...

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Motor nameplate showing insulation class and temperature rise
By longwell / September 9, 2026 / Fan Engineering Guides

Motor Insulation Class & Temperature Rise (F/H)

Insulation class sets the temperature a winding can survive. Temperatu...

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Fan motor nameplate showing IP ratings for ingress protection
By longwell / September 9, 2026 / Fan Engineering Guides

IP Ratings for Fans Explained (IP54/IP66)

IP ratings look simple until you need one. Here is what each digit act...

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Axial fan tip clearance between blade tips and the venturi ring
By longwell / September 9, 2026 / Fan Engineering Guides

Tip Clearance & Leakage in Fans

Air escaping past the blade tips is pure loss, and the gap causing it ...

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Reynolds number comparison between a small and a large fan impeller
By longwell / September 9, 2026 / Fan Engineering Guides

Reynolds Number: Scaling Fans Small to Large

Two geometrically identical fans of different sizes do not perform ide...

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Fan efficiency grade and FEI values compared on a performance curve
By longwell / September 9, 2026 / Fan Engineering Guides

Fan Efficiency Grade (FEG/FEI) Deep Dive

FEG rated the fan. FEI rates the selection. That single difference exp...

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Testing a fan run capacitor with a multimeter on the capacitance range
By longwell / September 9, 2026 / Fan Engineering Guides

How to Test & Replace a Fan Run Capacitor

A weak run capacitor causes slow starting, low speed and overheating, ...

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Single-phase and three-phase fan motors side by side on a bench
By longwell / September 8, 2026 / Fan Engineering Guides

Single-Phase vs Three-Phase Fan Motors

Above about 3 kW the choice makes itself, and below 1 kW it usually do...

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Fitting a VFD on any fan starts with checking the motor nameplate
By longwell / September 8, 2026 / Fan Engineering Guides

Can You Put a VFD on Any Fan?

A drive will spin almost any induction motor, though that is not the s...

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Wiring a fan speed controller to a single phase motor terminal block
By longwell / September 8, 2026 / Fan Engineering Guides

Wiring a Fan Speed Controller (Step by Step)

Speed controllers are not interchangeable, and fitting the wrong type ...

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