About This Book
ACCA Manual D (Residential Duct Systems) is the ANSI-recognized national standard for designing efficient residential HVAC duct systems.
Core Purpose
Manual D complements Manual J, which calculates the heating and cooling loads (in CFM) required for each room. Where Manual J determines how much airflow is needed, Manual D determines how to size, shape, and route the ductwork to deliver it.
It balances a home's airflow demands against the blower's available static pressure (TESP), and applies to all common duct materials—sheet metal, flex duct, and duct board—for both constant-volume and variable air volume (VAV) systems.
Key Components
- Friction Rate Calculation: Determines the allowable pressure drop per 100 feet of duct based on available static pressure and total equivalent length (TEL)
- Duct Sizing & Equivalent Lengths: Calculates pressure losses through straight runs, elbows, transitions, junction boxes, and grilles
- Blower Coordination: Ensures compatibility with single-speed, multi-speed, and variable-speed (ECM) blowers
- Code Compliance: Widely adopted by state and national building codes as the official residential duct design standard
Manual D is typically used alongside Manual J (load calculations) and Manual S (equipment selection).
Practice Tests Using This Book
This book is required or recommended for 4 licensing exams. We've written 22 practice questions directly from this material, each one citing the chapter and section it comes from.