The work: Substituting while the sheet metal duct fabricator is on vacation.
The apprentice: Allen Charles Edwards (ACE) — first-year mechanic.
The technician: N. Arthur Thomas Egan (NATE) — 15-year HVACR veteran.

NATE and ACE are working in the shop while the shop fabricator is on vacation. They are fabricating fittings for various jobs according to field drawings.

NATE: “Ace, since we’re working in the fabrication shop, it might be a good time to talk about the different types of duct systems. Can you identify the different types of duct systems shown in these drawings?”

Match the letter corresponding to the drawing with the system descriptions provided below.


System Types

1.Extended plenum:

2. Reducing plenum:

3. Reducing trunk system:

4. Radial system:

5. Perimeter loop system:


Usage Reasons

6.Used for equal friction method sizing:

7. Used in concrete to provide better comfort in heating:

8. Used in cold climates for maintaining comfort conditions at floor level on a concrete slab:

9. Used as the most common type of residential system:

10. Used like the extended plenum but equalizes the branch duct take-offs:

Author’s Note
Please remember no question appearing in these articles is on a NATE exam. These questions and dialogue are my creation alone. The NATE Technical Committee does not review the article content, and the committee has the final decision for the use of a question on the tests.

Interpretation of codes, regulations, and standards comes from my experience as a technician and a contractor. Different jurisdictions have varying interpretations. The particular area a job is being done in will dictate which viewpoint is to be properly used.

I learn a lot from your commentary and try to incorporate information into the next article, so please continue to comment.

e (Drawings courtesy of ACCA.)
Patrick L. Murphy
Director of Technical Development

Answers: 1) a; 2) d; 3) e; 4) b; 5) c; 6) a; 7) b; 8) c; 9) d; 10) e.

Patrick Murphy is director of technical development, North American Technician Excellence (NATE). If you have any further questions or comments on this quiz, contact Murphy at pmurphy@natex.org.

Publication date: 04/28/2003