Free CxA Practice Questions

Question 1

An office AHU cannot maintain its 55°F supply-air setpoint. After 30 minutes of steady operation, calibrated probes read 55°F immediately after the cooling coil and 64°F after the downstream hot-water coil. The heating command is 0%, and the actuator is at its closed stop. The fan is upstream of both probes; there is no other heat source between them. Which fault should lead the investigation?

Accepted Answer

Hot-water flow through the nominally closed heating valve.

Answer

Positive bias in the BAS supply-air temperature sensor.

Answer

Inadequate chilled-water flow at the cooling coil.

Answer

Excessive fan heat entering the airstream between the two measurements.

Question 2

The approved sequence requires a standby chilled-water pump to restore at least 95 gpm within 15 seconds of lead-pump failure and generate a BAS alarm. A draft functional test simply forces the standby pump ON and checks motor rotation. Safe fault simulation and system restoration procedures are already approved. Which replacement step would test the automatic failover function?

Accepted Answer

Trip the lead pump by the approved method while demand remains active; record automatic standby flow recovery and alarm timing.

Answer

Rotate the lead selection to the standby pump and verify that the newly selected lead delivers 95 gpm.

Answer

Force the standby pump ON, stop the lead manually, and record the time to recover 95 gpm.

Answer

Start each pump locally and compare its run-status indication with the corresponding startup record.

Question 3

Friday's commissioning visit includes full functional testing of two independent air-handling systems. AHU-East has completed startup, controls checkout, calibration, and TAB. AHU-West still lacks TAB. The approved plan permits separate testing, and there are no shared interlocks, outage constraints, or unresolved hazards affecting East. The contractor asks to postpone the entire visit. The CxA should revise the schedule to:

Accepted Answer

Test East as scheduled and defer West's airflow-dependent tests until its readiness is established.

Answer

Postpone both systems until the building-wide TAB effort is complete.

Answer

Use East's results to waive West's matching tests when their manufacturers and sequences are identical.

Answer

Test West's airflow-dependent sequences now and add its final TAB values to the records when they arrive.

Question 4

During a power-loss test, the generator and automatic transfer switch complete their specified sequence, with transfer in 9 seconds against a 12-second limit. A separately specified uninterruptible power supply (UPS) must keep the network rack continuously energized throughout the event. A recorder at that rack detects a 0.8-second loss of voltage, and the servers restart. Which acceptance conclusion is supported without assuming a root cause?

Accepted Answer

The source-transfer requirement passes; the protected-load continuity requirement fails.

Answer

Both requirements pass because the rack interruption is shorter than the permitted source-transfer interval.

Answer

The transfer delay is the failed component; shortening it will establish compliance with the uninterrupted-service requirement.

Answer

The UPS battery capacity is inadequate; the recorded interruption establishes that larger batteries are required.

Question 5

An existing AHU is undergoing an authorized minimum-outdoor-air test at 10,000 cfm total supply flow. Simultaneous calibrated readings are: return air 78°F, outdoor air 38°F, mixed air before the coils 70°F, and supply air after the active cooling coil 55°F. Mixing is complete, air-density differences are negligible, and no heat is added or removed before the mixed-air measurement. The required outdoor airflow is at least 2,500 cfm. What does the temperature-mixing calculation indicate?

Accepted Answer

2,000 cfm; it falls below the required outdoor airflow.

Answer

2,500 cfm; it just meets the minimum outdoor-air requirement.

Answer

5,750 cfm; it provides more outdoor air than required.

Answer

8,000 cfm; the outdoor airflow is greater than required.

Question 6

While investigating an AHU acceptance-test failure, a mechanic removes the belt guard after the fan has been stopped through the BAS. The fan is stationary, but its variable-frequency drive remains energized and automatic restart is enabled. The mechanic reaches toward the belt. What must the CxA do immediately?

Accepted Answer

Stop the adjustment until authorized personnel isolate hazardous energy and verify the safe state.

Answer

Have a controls technician hold the BAS output OFF and watch for any restart command.

Answer

Place and tag the local selector switch in OFF before allowing the adjustment.

Answer

Disable automatic restart in the drive and confirm zero displayed speed before permitting work behind the guard.

Question 7

A VAV terminal is holding a displayed airflow of 900 cfm at its 900-cfm setpoint, yet a calibrated duct traverse measures 600 cfm. The controller's differential-pressure input agrees with a reference manometer, and the manufacturer's correct pickup relationship also gives 600 cfm. There is no intervening duct leakage, and inlet pressure is adequate. Before changing the fan pressure or terminal setpoint, where should the CxA focus the correction?

Accepted Answer

The controller's pressure-to-airflow scaling, followed by a repeat airflow-control test.

Answer

The AHU static-pressure setpoint, increased to supply the missing airflow.

Answer

The branch-duct size, increased to remove the presumed restriction before repeating controls checkout.

Answer

The terminal airflow setpoint, increased until the traverse reaches 900 cfm without changing its scaling.

Question 8

A value-engineering proposal would delete a chiller's permanent water-flow meter. The owner's project requirements call for continuous kW/ton reporting across the operating-load range. Electrical input and entering/leaving water temperatures will still be measured. The pump has variable-speed control, but the proposal assumes the design flow confirmed during TAB whenever the chiller runs. Which response preserves the required function?

Accepted Answer

Retain a verified means of measuring operating flow for the required kW/ton calculation.

Answer

Use electrical input and water-temperature difference without a flow measurement.

Answer

Use the TAB design flow as the cooling-output input whenever the chiller operates.

Answer

Substitute pump differential pressure directly for flow without a calibrated curve.

Question 9

"The room matches the original drawings, but every evening class complains," says a facilities manager. A former eight-person office now accommodates 40 trainees until 9 p.m.; the original HVAC schedule ends at 6 p.m. Original commissioning and TAB records are complete, but no requirements have been established for the changed use. What should anchor the existing-building commissioning investigation?

Accepted Answer

Current facility requirements covering classroom occupancy, ventilation needs, and the evening operating schedule.

Answer

The original owner's requirements, retained unchanged because the building previously passed commissioning.

Answer

The original TAB airflows, maintained by running the entire building continuously.

Answer

The installed AHU's nameplate capacity, used to determine allowable classroom occupancy and operating hours without a current needs assessment.

Question 10

Everyone attended the chilled-water plant training. During supervised recovery exercises, two night-shift operators cannot identify the pump-flow permissive needed before a chiller restart. The other required tasks have been demonstrated successfully. The contract requires each operator to demonstrate plant recovery, not merely attend instruction. The training follow-up should be to:

Accepted Answer

Retrain the two operators on the recovery sequence and repeat their observed demonstration.

Answer

Accept their attendance and substitute a written component-identification quiz.

Answer

Repeat the complete training program for every operator before granting any credit.

Answer

Close the gap after both attend another general chiller product presentation.

Free CxA Practice Questions

Domain 1: Managing Commissioning Projects 18% of exam

Question 1

Question 2

Domain 2: Preparing Commissioning Documentation 19% of exam

Question 3

Domain 3: Conducting Commissioning Activities 24% of exam

Question 4

Question 5

Question 6

Domain 4: Managing Training Activities 4% of exam

Question 7

Domain 6: Conducting Existing Building Commissioning 23% of exam

Question 8

Question 9

Question 10

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