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These 10 free CAZ questions are organized by exam domain, so you can see how each part of the Combustion Appliance Zone Certification (CAZ) blueprint is tested. Reveal the answer and explanation under each question.
On a calm winter morning, a heated building's fans and air-handler blower are off. Repeated measurements along one exterior wall show negative indoor-to-outdoor pressure on the lowest floor and positive pressure on the uppermost floor. On a milder, equally calm day, both magnitudes are smaller with the equipment still off. What explains the height and temperature dependence?
Correct answer: C - Stack effect from the indoor-outdoor temperature difference.
A technician keeps a differential manometer in the hallway outside a closed combustion-appliance room. The required measurement is CAZ pressure relative to outdoors, rather than relative to the hallway. How should the input and reference ports be connected?
Correct answer: D - Input to the CAZ; reference connected to outdoors.
A manometer measuring CAZ pressure relative to outdoors stores a fan-off baseline of -1.6 Pa. Its adjusted display then shows operating pressure minus that stored baseline. With the exhaust fan running, the adjusted display reads -4.4 Pa. Conditions are stable, and no additional correction has been applied. The report has separate fields for raw operating pressure and fan-induced change. Which entries belong in those fields?
Correct answer: D - Raw operating pressure: -6.0 Pa; fan-induced change: -4.4 Pa.
For a furnace with an external return filter and an add-on cooling coil, the manufacturer specifies a maximum TESP of 0.80 in. w.c., measured between the furnace inlet and outlet. With clean components and the cabinet closed, readings relative to the same room are: before the filter, -0.06; furnace inlet, -0.24; furnace outlet before the coil, +0.38; after the coil, +0.20 in. w.c. All readings are from the same operating condition. Which commissioning conclusion follows?
Correct answer: C - TESP is 0.62 in. w.c.; the stated pressure limit is met, but airflow remains to be verified.
A horizontal supply duct expands through a transition containing no fan. Measurements confirm unchanged volume flow, lower mean air velocity downstream, and higher downstream static pressure. Air density is approximately constant. A trainee argues that the static-pressure rise proves the transition added energy to the air. Which explanation corrects that conclusion?
Correct answer: A - Velocity pressure can convert to static pressure while total pressure still decreases.
The main house and an enclosed appliance closet are both near outdoor pressure with the mechanical equipment off. Starting only the air-handler blower makes the house positive relative to outdoors and the closet negative relative to outdoors. Door positions and weather remain stable. Which defect best fits this combination?
Correct answer: B - A return-duct leak drawing air from the appliance closet.
A bedroom receives its required 100 CFM of supply air. Closing the bedroom door raises its pressure to +7 Pa relative to the hall; opening it reduces the difference to +1 Pa without changing supply airflow. New carpeting obstructs the existing door undercut. Which repair addresses the restriction while preserving the room's required airflow?
Correct answer: B - Restore the return-air path and verify pressure and supply airflow with the door closed.
While establishing a CAZ test configuration, a technician holds exhaust-fan settings constant and obtains these raw CAZ-to-outdoors pressures: blower off, door closed, -4.5 Pa; blower on, door closed, -2.8 Pa; blower off, door open, -6.0 Pa; blower on, door open, -3.4 Pa. The baseline and weather remain stable. For the subsequent appliance checks under ANSI/BPI-1200-S-2017, select the blower and CAZ-door settings.
Correct answer: A - Blower off; CAZ door open.
A field record for a natural-draft domestic water heater documents draft-hood spillage at 2 minutes of main-burner operation and 90 ppm air-free flue CO at 5 minutes. Ambient CO stayed at 2 ppm. The vent was cold before ignition. Under ANSI/BPI-1200-S-2017, the water-heater CO threshold is 200 ppm air-free. How should the spillage and CO findings be classified?
Correct answer: A - Record failed spillage and acceptable flue CO as separate findings.
Partway through a CAZ inspection, the technician's properly prepared, dedicated ambient CO monitor rises to 82 ppm. No occupant reports symptoms, and the source has not been identified. Under ANSI/BPI-1200-S-2017, what takes priority over completing the diagnostic work?
Correct answer: D - Stop testing, evacuate everyone, and arrange emergency assistance from outdoors.
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