ARLINGTON, Va. - Manual D® is the Air Conditioning Contractors of America (ACCA) standard for residential duct design. ACCA has now introduced a new CD training package that the association says takes the complex concepts of Manual D, explains them in plain English, and offers real-world examples on how to apply them in day-to-day business.

“Understanding Manual D: Airflow & Duct Design in the Real World” is the first in a new series of training materials being released by ACCA under the name “HVAC Essentials.” These recorded training sessions, which are viewed directly on a PC, are being developed to allow people (individually or in groups) to learn these concepts at their own pace, in segments or all at once, depending on their needs.

“Understanding Manual D” consists of five CDs, each including one segment of around 60 minutes. Each CD also includes appropriate handouts for easy printing.

The five CDs are:

Part 1 - Airflow Basics: Instruction on airflow basics, the fan laws, things to know about PSC motors, how to identify duct system types, an explanation of external static pressure, and how to read a blower performance chart.

Part 2 - Choosing a Blower: Understanding the myth of .10" static pressure. How to use an air duct calculator correctly. The friction rate formula is explained. How to choose an air handler or furnace blower.

Part 3 - Creating Comfort Using Manual T: The occupied zone is defined. Terminal velocity, register throw, drop and spread, and manufacturer’s engineering data are defined and discussed. How to choose a return grille; what constitutes a zone; and the general principles to properly handle return air are explained.

Part 4 - System Design: The 12 step procedure for using ACCA Manual D is explained and used to design and layout a trunk and branch duct system for a three-bedroom ranch house. This is a step-by-step procedure from the first trunk duct to the last branch run-out.

Part 5 - Testing and Balancing: What to do after the system is installed and running, including the use of a Magnehelic or manometer, location of static pressure tips, how to determine the system’s volume using blower performance charts, and component airflow data sheets.

“Understanding Manual D” is taught by Jack Rise, an HVAC trainer and ACCA EPIC-certified instructor.

The CD series can be purchased online at (under New Products) or by calling 888-290-2220.

Publication date:10/01/2007