NEVADA (NV) C-21B AIR-
CONDITIONING CONTRACTOR PRACTICE
EXAM 2026 100 QuEsTIONs &
ANswERs wITh DETAIlED
RATIONAlEs | COMPlETE EXAM PREP
& sTuDy GuIDE
TABLE OF CONTENTS
SECTION 1: HVAC FUNDAMENTALS & THERMODYNAMICS (Questions 1–20)
• Refrigeration Cycle Principles
• Sensible and Latent Heat
• Pressure-Temperature Relationships
• System Components and Functions
SECTION 2: LOAD CALCULATIONS & SYSTEM SIZING (Questions 21–35)
• Manual J, S, and D Applications
• Cooling and Heating Load Determination
• Duct Sizing and Airflow
• Equipment Selection Criteria
SECTION 3: SYSTEMS & EQUIPMENT (Questions 36–55)
• Split Systems and Packaged Units
, • Heat Pumps and Reversing Valves
• Furnaces and Air Handlers
• Condensers, Evaporators, and Compressors
SECTION 4: CONTROLS & ELECTRICAL SYSTEMS (Questions 56–70)
• Low-Voltage Wiring and Thermostats
• NEC Article 440 Requirements
• Motors, Capacitors, and Relays
• Electrical Safety and Troubleshooting
SECTION 5: PIPING, REFRIGERANTS & EPA 608 (Questions 71–85)
• Refrigerant Types and Phase-Outs
• Charging and Recovery Procedures
• Gas Piping and Condensate Drainage
• EPA Section 608 Compliance
SECTION 6: CODES, SAFETY & OSHA (Questions 86–95)
• Uniform Mechanical Code (UMC)
• OSHA 1926 Safety Protocols
• Pressure Testing and Combustion Air
• Equipment Clearances and Ventilation
SECTION 7: NEVADA CONTRACTOR LAW & BUSINESS (Questions 96–100)
• NAC 624.380 Classification Requirements
• Bond, Insurance, and Licensing
• NRS 624 Regulations
SECTION 1: HVAC FUNDAMENTALS & THERMODYNAMICS
, Correct answers are marked with two red dots.
Q1. What is the primary function of an air conditioning system as defined for a C-21B
contractor in Nevada?
A) To provide complete building automation
B) To regulate indoor temperature and humidity
C) To serve as a primary heating source only
D) To replace mechanical ventilation systems
Answer: B
Rationale: Under NAC 624.380, the C-21B subclassification specifically covers equipment
that uses evaporation, refrigeration, boilers, or combustion for the control of air temperatures
in structures, including humidity and thermostatic controls. HVAC systems regulate
environmental comfort and air quality.
Q2. What is the primary difference between sensible heat and latent heat?
A) Sensible heat changes temperature; latent heat changes phase
B) Sensible heat changes pressure; latent heat changes volume
C) Sensible heat is measured in BTU/hr; latent heat in kW
D) Sensible heat is only in cooling; latent heat only in heating
Answer: A
Rationale: Sensible heat results in a temperature change without a phase change, while
latent heat involves a phase change (e.g., condensation or evaporation) at constant
temperature. Sensible heat changes the temperature of air without changing its moisture
content.
Q3. Refrigerant in an HVAC system is primarily used to:
A) Heat water for domestic use
B) Absorb and release heat through phase changes
, C) Lubricate mechanical components
D) Provide structural support to the system
Answer: B
Rationale: Refrigerant cycles transfer heat for cooling and heating by absorbing heat during
evaporation and releasing heat during condensation.
Q4. Which component of the refrigeration cycle is responsible for compressing low-
pressure refrigerant vapor into high-pressure, high-temperature vapor?
A) Evaporator
B) Condenser
C) Compressor
D) Expansion valve
Answer: C
Rationale: The compressor is the heart of the refrigeration cycle, drawing in low-pressure
refrigerant vapor and compressing it to a high-pressure, high-temperature state before it enters
the condenser.
Q5. What is the primary purpose of a condenser in an air conditioning system?
A) To evaporate refrigerant
B) To absorb heat from indoor air
C) To release heat to the outside environment
D) To compress the refrigerant
Answer: C
Rationale: The condenser removes heat from the refrigerant, allowing it to condense back
into liquid form. It releases the heat absorbed from the indoor space to the outdoor
environment.
CONDITIONING CONTRACTOR PRACTICE
EXAM 2026 100 QuEsTIONs &
ANswERs wITh DETAIlED
RATIONAlEs | COMPlETE EXAM PREP
& sTuDy GuIDE
TABLE OF CONTENTS
SECTION 1: HVAC FUNDAMENTALS & THERMODYNAMICS (Questions 1–20)
• Refrigeration Cycle Principles
• Sensible and Latent Heat
• Pressure-Temperature Relationships
• System Components and Functions
SECTION 2: LOAD CALCULATIONS & SYSTEM SIZING (Questions 21–35)
• Manual J, S, and D Applications
• Cooling and Heating Load Determination
• Duct Sizing and Airflow
• Equipment Selection Criteria
SECTION 3: SYSTEMS & EQUIPMENT (Questions 36–55)
• Split Systems and Packaged Units
, • Heat Pumps and Reversing Valves
• Furnaces and Air Handlers
• Condensers, Evaporators, and Compressors
SECTION 4: CONTROLS & ELECTRICAL SYSTEMS (Questions 56–70)
• Low-Voltage Wiring and Thermostats
• NEC Article 440 Requirements
• Motors, Capacitors, and Relays
• Electrical Safety and Troubleshooting
SECTION 5: PIPING, REFRIGERANTS & EPA 608 (Questions 71–85)
• Refrigerant Types and Phase-Outs
• Charging and Recovery Procedures
• Gas Piping and Condensate Drainage
• EPA Section 608 Compliance
SECTION 6: CODES, SAFETY & OSHA (Questions 86–95)
• Uniform Mechanical Code (UMC)
• OSHA 1926 Safety Protocols
• Pressure Testing and Combustion Air
• Equipment Clearances and Ventilation
SECTION 7: NEVADA CONTRACTOR LAW & BUSINESS (Questions 96–100)
• NAC 624.380 Classification Requirements
• Bond, Insurance, and Licensing
• NRS 624 Regulations
SECTION 1: HVAC FUNDAMENTALS & THERMODYNAMICS
, Correct answers are marked with two red dots.
Q1. What is the primary function of an air conditioning system as defined for a C-21B
contractor in Nevada?
A) To provide complete building automation
B) To regulate indoor temperature and humidity
C) To serve as a primary heating source only
D) To replace mechanical ventilation systems
Answer: B
Rationale: Under NAC 624.380, the C-21B subclassification specifically covers equipment
that uses evaporation, refrigeration, boilers, or combustion for the control of air temperatures
in structures, including humidity and thermostatic controls. HVAC systems regulate
environmental comfort and air quality.
Q2. What is the primary difference between sensible heat and latent heat?
A) Sensible heat changes temperature; latent heat changes phase
B) Sensible heat changes pressure; latent heat changes volume
C) Sensible heat is measured in BTU/hr; latent heat in kW
D) Sensible heat is only in cooling; latent heat only in heating
Answer: A
Rationale: Sensible heat results in a temperature change without a phase change, while
latent heat involves a phase change (e.g., condensation or evaporation) at constant
temperature. Sensible heat changes the temperature of air without changing its moisture
content.
Q3. Refrigerant in an HVAC system is primarily used to:
A) Heat water for domestic use
B) Absorb and release heat through phase changes
, C) Lubricate mechanical components
D) Provide structural support to the system
Answer: B
Rationale: Refrigerant cycles transfer heat for cooling and heating by absorbing heat during
evaporation and releasing heat during condensation.
Q4. Which component of the refrigeration cycle is responsible for compressing low-
pressure refrigerant vapor into high-pressure, high-temperature vapor?
A) Evaporator
B) Condenser
C) Compressor
D) Expansion valve
Answer: C
Rationale: The compressor is the heart of the refrigeration cycle, drawing in low-pressure
refrigerant vapor and compressing it to a high-pressure, high-temperature state before it enters
the condenser.
Q5. What is the primary purpose of a condenser in an air conditioning system?
A) To evaporate refrigerant
B) To absorb heat from indoor air
C) To release heat to the outside environment
D) To compress the refrigerant
Answer: C
Rationale: The condenser removes heat from the refrigerant, allowing it to condense back
into liquid form. It releases the heat absorbed from the indoor space to the outdoor
environment.
