I Built a Miniature Duct System to Show What Ruins Airflow

A plain introduction to Manual D and duct design. I show how friction rate is calculated from "total effective length" and why the length of a duct run can be deceiving. 00:00 – Why a Short Run Can Act Long 00:27 – Starting a Duct Design 01:00 – What Happens If You Exceed the Budget 01:35 – Finding the Furthest Room 02:21 – Measuring Linear Distance 03:03 – Measuring Effective Length 04:48 – Example Run Calculation 05:28 – Static Pressure Demo – No Fitting vs. Soft 90 05:59 – Static Pressure Demo – Hard 90 06:26 – Don’t Forget the Return Side 07:05 – Subtracting for Coil and Filter 07:52 – Calculating Friction Rate 08:18 – Why This Matters for Everyone 09:01 – Closing Notes