Nevada (NV) C-21B Air Conditioning Contractor Practice
Exam 2026 | 2 Full Version| 400 questions and expert
rationale | Guaranteed pass
DESCRIPTION
The Nevada (NV) C-21B Air Conditioning contractor exam is an open-book trade
assessment required for licensing to install and repair residential and commercial
HVAC systems. It is administered by PSI and must be paired with the Construction
Management Survey (CMS) exam to obtain a valid Nevada license.
CORE EXAM DOMAINS
The exam tests proficiency across the full lifecycle of air conditioning systems:
1. Load Calculations (15%): Using Manual J, S, and D to determine
cooling/heating requirements and duct sizing.
2. Systems & Equipment (25%): Installation and operation of A/C units, heat
pumps, furnaces, and ventilation.
3. Controls (15%): Low-voltage wiring, thermostats, and electrical
safety/troubleshooting.
4. Piping & Refrigerants (20%): Refrigerant handling (EPA 608), gas piping, and
condensate drainage.
5. General Knowledge & Safety (25%): Thermodynamics, UMC codes, OSHA
safety standards, and pressure testing.
,NEVADA C-21B PRACTICE EXAM — 2 VERSIONS
1. According to the Uniform Mechanical Code (UMC), what is the minimum
clearance required in front of a furnace control side for service and
inspection?
A. 18 inches
B. 24 inches
C. 30 inches
D. 36 inches
Answer: C
Rationale: To ensure technician safety and proper tool maneuverability, the UMC
requires a minimum of 30 inches of working space in front of the control side of
the equipment. This allows for the safe removal of burners, blowers, and controls
without obstruction.
2. When installing a condensate drain line for a high-efficiency furnace, what
is the minimum slope required to ensure proper drainage?
,A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
Answer: B
Rationale: Gravity-fed condensate lines must maintain a minimum slope of 1/4
inch per foot (2% grade). If the slope is too shallow, biofilm (slime) can build up,
leading to clogs, water damage, and system shutdowns via the float switch.
3. In a heat pump system, the "Reversing Valve" is typically energized in
which mode for most manufacturers?
A. Heating
B. Cooling
C. Defrost only
D. Emergency heat only
Answer: B
Rationale: While some brands vary (like Rheem/Ruud), the industry standard
(Carrier, Trane, Goodman) is for the reversing valve (O-terminal) to be energized
in the cooling mode. This allows the system to fail-safe into the heating mode
during winter if the solenoid coil fails.
, 4. What is the maximum permitted length of a flexible air duct (flex duct)
according to standard Nevada energy conservation codes?
A. 5 feet
B. 10 feet
C. 14 feet
D. 25 feet
Answer: C
Rationale: While some jurisdictions allow longer runs, the general standard for
efficiency is to limit flexible ducts to 14 feet. Excessively long flex duct runs
significantly increase static pressure and reduce airflow due to the internal friction
of the wire helix.
5. According to the International Fuel Gas Code (IFGC), a gas shut-off valve
must be located within how many feet of the appliance it serves?
A. 3 feet
B. 6 feet
C. 10 feet
D. Within the same room, no distance limit
Answer: B
Rationale: The shut-off valve must be in the same room and within 6 feet of the
appliance. This ensures that in the event of a gas leak or fire at the unit, a
technician or occupant can quickly and safely isolate the fuel source.
Exam 2026 | 2 Full Version| 400 questions and expert
rationale | Guaranteed pass
DESCRIPTION
The Nevada (NV) C-21B Air Conditioning contractor exam is an open-book trade
assessment required for licensing to install and repair residential and commercial
HVAC systems. It is administered by PSI and must be paired with the Construction
Management Survey (CMS) exam to obtain a valid Nevada license.
CORE EXAM DOMAINS
The exam tests proficiency across the full lifecycle of air conditioning systems:
1. Load Calculations (15%): Using Manual J, S, and D to determine
cooling/heating requirements and duct sizing.
2. Systems & Equipment (25%): Installation and operation of A/C units, heat
pumps, furnaces, and ventilation.
3. Controls (15%): Low-voltage wiring, thermostats, and electrical
safety/troubleshooting.
4. Piping & Refrigerants (20%): Refrigerant handling (EPA 608), gas piping, and
condensate drainage.
5. General Knowledge & Safety (25%): Thermodynamics, UMC codes, OSHA
safety standards, and pressure testing.
,NEVADA C-21B PRACTICE EXAM — 2 VERSIONS
1. According to the Uniform Mechanical Code (UMC), what is the minimum
clearance required in front of a furnace control side for service and
inspection?
A. 18 inches
B. 24 inches
C. 30 inches
D. 36 inches
Answer: C
Rationale: To ensure technician safety and proper tool maneuverability, the UMC
requires a minimum of 30 inches of working space in front of the control side of
the equipment. This allows for the safe removal of burners, blowers, and controls
without obstruction.
2. When installing a condensate drain line for a high-efficiency furnace, what
is the minimum slope required to ensure proper drainage?
,A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
Answer: B
Rationale: Gravity-fed condensate lines must maintain a minimum slope of 1/4
inch per foot (2% grade). If the slope is too shallow, biofilm (slime) can build up,
leading to clogs, water damage, and system shutdowns via the float switch.
3. In a heat pump system, the "Reversing Valve" is typically energized in
which mode for most manufacturers?
A. Heating
B. Cooling
C. Defrost only
D. Emergency heat only
Answer: B
Rationale: While some brands vary (like Rheem/Ruud), the industry standard
(Carrier, Trane, Goodman) is for the reversing valve (O-terminal) to be energized
in the cooling mode. This allows the system to fail-safe into the heating mode
during winter if the solenoid coil fails.
, 4. What is the maximum permitted length of a flexible air duct (flex duct)
according to standard Nevada energy conservation codes?
A. 5 feet
B. 10 feet
C. 14 feet
D. 25 feet
Answer: C
Rationale: While some jurisdictions allow longer runs, the general standard for
efficiency is to limit flexible ducts to 14 feet. Excessively long flex duct runs
significantly increase static pressure and reduce airflow due to the internal friction
of the wire helix.
5. According to the International Fuel Gas Code (IFGC), a gas shut-off valve
must be located within how many feet of the appliance it serves?
A. 3 feet
B. 6 feet
C. 10 feet
D. Within the same room, no distance limit
Answer: B
Rationale: The shut-off valve must be in the same room and within 6 feet of the
appliance. This ensures that in the event of a gas leak or fire at the unit, a
technician or occupant can quickly and safely isolate the fuel source.
