Free NATE-AIR-DIST-INSTALL Practice Questions

Question 1

An 8-inch flexible supply branch delivers much less air than scheduled. Its damper is fully open, its connections are airtight, and the other branches deliver their scheduled airflow. In the attic, 25 feet of flex has been bunched into a 14-foot route with a tight loop. The approved layout specifies an 8-inch branch along that route. What should be corrected before another balancing attempt?

Accepted Answer

Shorten and fully extend the flex, using broad bends and nonconstricting supports.

Answer

Increase blower speed and rebalance the other branches.

Answer

Replace the branch with 10-inch flex while retaining the existing looped route.

Answer

Partially close the other branch dampers until this outlet reaches its scheduled flow.

Question 2

During furnace start-up, the temperature rise reaches 74°F; the nameplate permits 35-65°F. Gas input is correct, the filter and coil are clean, the ducts are unobstructed, and blower rotation is correct. The cooling airflow setting is appropriate, but the heating setting is the lowest approved tap. The high limit opens late in each heating cycle. Which adjustment addresses this evidence?

Accepted Answer

Select a higher approved heating-blower setting and recheck the temperature rise.

Answer

Reduce gas input to bring temperature rise into range.

Answer

Extend blower-off delay to remove more heat between cycles.

Answer

Replace the high-limit control before making changes to airflow.

Question 3

A shop drawing specifies a metal duct with inside dimensions of 20 by 14 inches before lining. The installed duct has 1-inch liner on all four walls. A valid equal-area traverse gives an average velocity of 600 feet per minute across the remaining clear opening. The acceptable airflow for this section is 810-990 CFM. Which airflow and disposition belong on the start-up sheet?

Accepted Answer

About 900 CFM; within the acceptable range.

Answer

About 1,167 CFM; above the acceptable range.

Answer

About 1,029 CFM; the flow exceeds the allowable maximum.

Answer

About 667 CFM; below the acceptable range.

Question 4

Water accumulates in a new draw-through air handler's drain pan only while the blower runs. When the blower stops, the pan empties promptly. The drain is clear, slopes correctly, and terminates freely. Its trap is primed, but the effective water seal is shallower than the unit requires. An installer proposes a vent tee between the pan and the trap. What should be done instead?

Accepted Answer

Rebuild the trap to the required seal depth and verify drainage with the blower running.

Answer

Install a larger downstream drain while retaining the existing trap and water-seal depth.

Answer

Increase the downstream pipe slope so water leaves the existing shallow trap more quickly.

Answer

Reduce the cooling blower speed until the shallow trap drains, then retain that speed for normal operation.

Question 5

With both pressure ports open to the same room, an electronic manometer reads +0.12 in. w.c. The technician then connects it to the supply and return test ports and obtains a higher-than-expected pressure reading. No equipment adjustment has been made. How should the technician handle this result?

Accepted Answer

Check the meter setup and zero, then repeat the pressure measurement.

Answer

Adjust blower speed to reduce the displayed static pressure.

Answer

Remove the air handler from service until its excessive static pressure has been corrected.

Answer

Ignore the offset; it cancels during a differential measurement.

Question 6

At blower start and stop, a broad rectangular return-duct panel snaps inward or outward with one loud pop. It is quiet at steady fan speed. Supports and joints are secure, the blower wheel turns smoothly, and measured static pressure is within the equipment's operating range. Which repair most directly targets the noise?

Accepted Answer

Stiffen the flexing panel with reinforcement appropriate to the duct construction.

Answer

Add vibration isolators beneath the blower support frame.

Answer

Realign the blower wheel and replace its bearings to eliminate vibration from rotating components.

Answer

Reseal the transverse joints to eliminate whistling caused by air moving through small gaps.

Question 7

During start-up after return-duct replacement, a home's carbon monoxide alarm sounds. The homeowner reports a headache, and another occupant feels dizzy. The furnace is operating in the basement. What takes priority over further equipment testing?

Accepted Answer

Get everyone outdoors and call emergency services from outside.

Answer

Turn off the furnace, then identify the source before deciding whether evacuation is necessary.

Answer

Open windows and run the circulating blower while checking whether the occupants' symptoms improve.

Answer

Check ambient carbon monoxide with a second instrument before treating the alarm as confirmed.

Question 8

While fabricating rectangular duct, a sheet-metal worker forms one longitudinal edge into a pocket. The mating edge receives a right-angle flange, which is inserted into that pocket before the exposed locking edge is hammered closed. This connection is a:

Accepted Answer

Pittsburgh lock seam

Answer

Standing S-slip transverse connection

Answer

Round-pipe snap-lock seam

Answer

Drive-slip transverse joint

Question 9

A vertical wall penetration requires a fire damper that can close while the supply fan continues operating. Closure conditions can reach 2,500 feet per minute and 1.5 in. w.c. All four candidates have the required fire-resistance rating and size. Which listing satisfies the installation conditions?

Accepted Answer

Dynamic-rated; closure limits of 3,000 FPM and 4.0 in. w.c.; listed for vertical walls.

Answer

Static-rated; listed for vertical walls in systems that stop airflow before damper closure.

Answer

Dynamic-rated; closure limits of 2,000 FPM and 4.0 in. w.c.; listed for vertical walls.

Answer

Dynamic-rated; closure limits of 3,000 FPM and 4.0 in. w.c.; listed only for horizontal floor installations.

Question 10

A constant-airflow ECM blower is programmed for 1,200 CFM. After a more restrictive filter is installed, measured airflow remains near 1,200 CFM, but blower speed and electrical power increase. The motor remains within its approved operating envelope. What does this behavior indicate?

Accepted Answer

The blower is compensating for added resistance to maintain its programmed airflow.

Answer

A motor-control fault requires replacement of the ECM.

Answer

Filter bypass has eliminated the added resistance and preserved airflow.

Answer

Less system resistance requires more motor power at unchanged airflow.

Free NATE-AIR-DIST-INSTALL Practice Questions

Domain 1: Installation

Question 1

Question 2

Question 3

Question 4

Domain 2: Service

Question 5

Domain 3: System Components

Question 6

Question 7

Question 8

Domain 4: Applied Knowledge

Question 9

Question 10

That's 10 of 1,030