Free Air Distribution - Installation Specialty Exam Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Air Distribution - Installation Specialty Exam practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A worker is laying out the longitudinal closure of a straight sheet-metal supply duct. How should that seam run relative to airflow?

   1. A.Parallel to airflowCorrect answer: A
   2. B.Perpendicular to airflow
   3. C.Diagonally across each end
   4. D.Circumferentially around each end

   Explanation: The source states: "Longitudinal seams are joints in the direction of airflow." The longitudinal closure follows the length of the air path. Perpendicular and circumferential closures join duct ends; a diagonal line does not define a longitudinal seam.

   Reference: ASHRAE Handbook: Duct Construction — HVAC System Leakage — System Sealing

2. 2An inspection finds a return-duct opening drawing air from a hot attic during cooling. What is the direct thermal effect of this leak?

   1. A.Lower return temperature and more cooling capacity
   2. B.Higher return temperature and less cooling capacityCorrect answer: B
   3. C.Lower supply pressure and more cooling capacity
   4. D.Higher refrigerant efficiency and less heat gain

   Explanation: The source states: "leaks from a hot attic into a return duct heat the return air, which in turn reduces system cooling capacity." Hot attic air adds heat to the return stream and reduces effective cooling. The other choices reverse that effect or assign an unsupported benefit.

   Reference: ASHRAE Handbook: Duct Construction — HVAC System Leakage

3. 3Warm air moving across a cooler coil carries thermal energy from the air to the coil. Which heat-transfer mode describes energy transfer associated with this fluid movement?

   1. A.Conduction
   2. B.ConvectionCorrect answer: B
   3. C.Radiation
   4. D.Fusion

   Explanation: The source states: "The movement of fluid such as air or water can transfer heat." Convection involves fluid motion. Conduction acts through material contact, radiation through electromagnetic energy, and fusion is melting rather than this transport mode.

   Reference: Natural Resources Canada: How Your House Works — How your house works — Heat flow — Convection

4. 4A contractor proposes applying a pesticide biocide inside a duct. What controls whether that particular use is legally permitted under EPA's guidance?

   1. A.The manufacturer's general hard-surface sanitizer claim
   2. B.The customer's written permission to apply it
   3. C.The product's registered use and label directionsCorrect answer: C
   4. D.The contractor's trade-license classification

   Explanation: The source states: "A product must be registered by EPA for a specific use before it can be legally used for that purpose." The specific EPA registration and label govern this use; marketing, consent and trade licensing do not authorize unlisted pesticide applications. It also states: "It is a violation of federal law to use a pesticide product in any manner inconsistent with the label directions."

   Reference: EPA: Should You Have the Air Ducts in Your Home Cleaned? — Should chemical biocides be applied to the inside of air ducts?

5. 5A rectangular sheet-metal transition reduces from a large trunk to a smaller branch. Which size governs its material thickness under ASHRAE's construction guidance?

   1. A.The smaller fitting dimension
   2. B.The greater fitting dimensionCorrect answer: B
   3. C.The average of the end dimensions
   4. D.The difference between end dimensions

   Explanation: The source states: "On size change fittings, the greater fitting dimension determines material thickness." Use the larger fitting dimension when selecting thickness; averaging, subtracting, or using only the reduced end understates the controlling size.

   Reference: ASHRAE Handbook: Duct Construction — Round, Flat Oval, and Rectangular Ducts — Rectangular Ducts

6. 6A fan transmits objectionable mechanical vibration into nearby ductwork and framing. Which intervention directly reduces transmitted vibration energy?

   1. A.An internal acoustic duct liner
   2. B.A larger low-velocity discharge grille
   3. C.Suitable rubber or spring isolation mountsCorrect answer: C
   4. D.Greater separation from occupied rooms

   Explanation: The source states: "mounting the fan on a soft material, such as rubber or suitable spring isolator as required to limit the amount of transmitted vibration energy" Mechanical isolation limits transmitted vibration; the alternatives address airborne noise or occupant exposure.

   Reference: DOE Improving Fan System Performance — Introduction to Fan Systems — Noise

7. 7In an operating air-conditioning evaporator, liquid refrigerant changes to vapor while room air is cooled. What occurs to heat during this phase change?

   1. A.The refrigerant releases heat to the air
   2. B.The air gains heat from condensation
   3. C.The refrigerant absorbs heat from the airCorrect answer: C
   4. D.The air is cooled without heat transfer

   Explanation: The source states: "The absorbed heat causes the refrigerant to turn to a low-pressure vapor again" The refrigerant absorbs heat and evaporates, removing heat from air. Heat rejection/condensation is the opposite process; cooling is not an absence of heat transfer.

   Reference: DOE Air Conditioning — The Refrigerant Cycle

8. 8Which duct material does EPA identify as having no currently registered biocide products for application to its interior?

   1. A.Bare sheet-metal supply duct
   2. B.Unlined metal return duct
   3. C.Smooth unlined metal duct
   4. D.Fiberglass duct boardCorrect answer: D

   Explanation: The source states: "No products are currently registered by EPA as biocides for use on fiberglass duct board or fiberglass lined ducts" This restriction concerns fiberglass duct board and liner. EPA distinguishes them from certain label-authorized uses on bare metal; it does not authorize every product on metal.

   Reference: EPA: Should You Have the Air Ducts in Your Home Cleaned? — Should chemical biocides be applied to the inside of air ducts?

9. 9A shop is fabricating a large rectangular duct. What structural function can a properly designed transverse joint serve?

   1. A.Supporting the external vapor retarder
   2. B.Providing internal sound absorption
   3. C.Reinforcing the duct against deformationCorrect answer: C
   4. D.Equalizing air velocity across the section

   Explanation: The source states: "Transverse joints (e.g., standing drive slips, pocket locks, and companion angles) and, when necessary, intermediate structural members and tie rods are designed to reinforce the duct system." The joint can act as structural reinforcement. Vapor control, acoustic absorption, and velocity equalization are different functions and do not describe this joint's structural purpose.

   Reference: ASHRAE Handbook: Duct Construction — Round, Flat Oval, and Rectangular Ducts — Rectangular Ducts

10. 10A rigid-metal duct connection has separated after its old tape failed. In DOE's repair method, what is the minimum specified screw count to secure it before mastic is applied?

    1. A.At least one specified sheet-metal screw
    2. B.At least two specified sheet-metal screws
    3. C.At least four specified sheet-metal screws
    4. D.At least three specified sheet-metal screwsCorrect answer: D

    Explanation: The source states: "Secure the duct connection using at least three #7 x ½-inch self-piercing/self-drilling sheet metal screws." Three is the stated minimum; one and two are below it, while four exceeds it.

    Reference: Air Seal and Repair Ducts — Re-Connecting Rigid Duct Connections