Nevada Refrigeration and Air Conditioning Contractor (C-21) Books Allowed into Exam Package

Prepare for the Nevada Refrigeration and Air Conditioning Contractor (C-21) examination with a focused exam-room package containing the two code references candidates are allowed to use during the open-book trade test: the Uniform Mechanical Code, 2018 and NFPA 54 - Standard for National Fuel Gas Code, 2012.

This package is designed specifically for candidates who want the books allowed into the Nevada C-21 examination rather than a larger study package containing supplemental technical references that are not permitted in the testing room. The two included books support code-based preparation for refrigeration, air conditioning, mechanical systems, fuel-gas piping, ventilation, equipment, combustion air, venting, and related installation requirements.

The Nevada C-21 examination is an open-book test. The trade exam contains 85 questions, allows 3 hours for completion, and requires 60 correct answers to pass. The examination covers a broad range of refrigeration and air-conditioning topics, including fuel systems, refrigerants and refrigeration, piping, load calculations, ducts, controls, heating equipment, chillers, hydronics, solar systems, ventilation, testing, safety, and evaporative cooling.

The C-21 Refrigeration and Air Conditioning classification is broad because it covers work involving refrigeration systems, air-conditioning equipment, ductwork, sheet metal associated with HVAC systems, chilled-water systems, solar air-conditioning equipment, and hot-water piping used for temperature control. Candidates should therefore prepare for both refrigeration and mechanical-system knowledge rather than concentrating on one narrow area.

The Uniform Mechanical Code, 2018 supports many mechanical and HVAC-related topics on the exam, while NFPA 54, 2012 supports natural gas and fuel-gas questions. Candidates should become comfortable deciding which reference applies before starting a lookup.

Open-book testing still requires strong trade knowledge. With 85 questions in three hours, candidates have only a little more than two minutes per question on average. Efficient preparation should combine technical understanding with reference-navigation practice so the approved books can be used strategically rather than searched from beginning to end for every answer.

What You Get

• Uniform Mechanical Code, 2018 — exam-room-approved reference supporting refrigeration, air conditioning, heating, mechanical equipment, ventilation, ducts, piping, hydronics, combustion air, and related mechanical requirements.
• NFPA 54 - Standard for National Fuel Gas Code, 2012 — exam-room-approved reference supporting natural gas piping, appliance installation, sizing, testing, combustion air, venting, regulators, and other fuel-gas system requirements.
• Focused Exam-Room Package: This product contains the two books approved for use during the Nevada C-21 trade examination.
• Open-Book Exam Preparation: Use the same approved references during study sessions to build familiarity and improve lookup speed before test day.
• Code Navigation Practice: Learn how to move efficiently through mechanical and fuel-gas requirements under timed conditions.

Exam Details

The Nevada C-21 Refrigeration and Air Conditioning Contractor examination contains 85 questions. Candidates are allowed 3 hours to complete the examination and must answer 60 questions correctly to pass.

The examination content is divided into the following subject areas:

• Piping: 6 questions
• Insulation: 1 question
• Hangers and Supports: 3 questions
• Sound, Vibration and Seismic Control: 1 question
• Heating and Cooling Principles: 3 questions
• Refrigerants and Refrigeration: 7 questions
• Load Calculations: 6 questions
• Testing, Adjusting and Balancing: 3 questions
• Controls: 5 questions
• Machine Room: 1 question
• A/C and Heat Pump Equipment: 4 questions
• Furnaces and Heaters: 4 questions
• Hydronics: 2 questions
• Chimneys, Flues and Vents: 5 questions
• Combustion Air: 2 questions
• Fuel Systems: 10 questions
• Ducts: 6 questions
• Evaporative Cooling: 2 questions
• Chillers: 3 questions
• Solar: 4 questions
• Ventilation and Exhausts: 3 questions
• Safety: 4 questions

Fuel Systems is the largest individual category with 10 questions. Refrigerants and Refrigeration accounts for 7 questions, while Piping, Load Calculations, and Ducts each account for 6 questions.

Because the exam spreads questions across many technical areas, candidates should build a balanced study plan. Concentrating only on refrigeration theory or only on mechanical code navigation can leave major parts of the exam underprepared.

Open Book Test

The Nevada C-21 Refrigeration and Air Conditioning Contractor examination is an open-book test.

The following references included in this package are allowed into the examination:

• Uniform Mechanical Code, 2018
• NFPA 54 - Standard for National Fuel Gas Code, 2012

The Uniform Mechanical Code should be used when preparing for refrigeration, mechanical equipment, air conditioning, heating, ducts, ventilation, hydronics, piping, chillers, furnaces, combustion-air requirements, and other mechanical-system topics.

NFPA 54 should be used when preparing for natural gas piping, appliance connections, regulators, sizing, testing, combustion air, chimneys, flues, vents, and related fuel-gas requirements.

Knowing which book applies to a question is one of the most important open-book skills. If a candidate understands the topic but chooses the wrong reference, valuable time can be lost searching sections that do not contain the answer.

Timed navigation drills can help. Select a topic such as refrigeration equipment, ventilation, gas piping, combustion air, or venting, then identify the correct book and locate the applicable section as efficiently as possible.

Open-book testing does not mean candidates should look up every answer. Many technical questions involving refrigeration principles, controls, load calculations, ducts, and system operation should be approached from trade knowledge first. The code books are most useful when a specific requirement, definition, table, clearance, installation rule, or fuel-gas provision needs to be confirmed.

Licensing Steps

1. Confirm the C-21 classification. Make sure Refrigeration and Air Conditioning Contracting matches the work the business intends to perform.
2. Identify the qualifying individual. The contractor application must identify the person responsible for satisfying the applicable trade qualification requirements.
3. Document qualifying experience. Prepare the required work-history information supporting refrigeration and air-conditioning experience.
4. Submit the Nevada contractor license application. Complete the applicable application and supporting documentation.
5. Receive examination eligibility. After the application and qualification information are reviewed, the qualifying individual can proceed with the required examinations.
6. Prepare for the C-21 trade examination. Study refrigeration, air conditioning, fuel systems, piping, ducts, controls, heating, hydronics, chillers, ventilation, and related subjects.
7. Practice with both approved references. Use the Uniform Mechanical Code and NFPA 54 regularly during preparation.
8. Prepare for Nevada Business and Law. Contractor applicants must satisfy the applicable Nevada business and law requirement unless an authorized waiver applies.
9. Complete the required examinations. Take the applicable trade and business examinations.
10. Complete remaining licensing requirements. Finish the additional requirements associated with issuance of the Nevada contractor license.

State Requirements

Nevada's C-21 Refrigeration and Air Conditioning classification covers a broad range of refrigeration, HVAC, and related mechanical work.

The scope includes refrigeration systems used to control temperatures below 50°F in refrigerated rooms and insulated spaces, together with related insulation, ducts, blowers, registers, humidity controls, thermostatic controls, and specified gas and electrical connections.

The classification also includes installation, repair, service, and maintenance of air-conditioning equipment and related ductwork used to control temperatures in occupied structures.

C-21 work can also include sheet metal associated with HVAC systems, repair and replacement of refrigeration and air-conditioning components, solar equipment used for air-temperature control, chilled-water systems, and hot-water piping used for temperature control.

This broad scope explains why the examination includes refrigeration, air conditioning, fuel systems, ductwork, load calculations, piping, controls, hydronics, chillers, solar, ventilation, safety, and other mechanical-system topics.

The C-21 trade examination is one part of the Nevada contractor licensing process. Applicants must also satisfy applicable qualification, application, business and law, and other state licensing requirements before a contractor license is issued.

Reference Books

• Uniform Mechanical Code, 2018
  This exam-room-approved reference supports preparation involving refrigeration, air conditioning, heating, mechanical equipment, ducts, ventilation, hydronics, piping, chillers, combustion air, furnaces, equipment rooms, and related mechanical requirements.
• NFPA 54 - Standard for National Fuel Gas Code, 2012
  This exam-room-approved reference supports preparation involving natural gas piping, appliance installation, sizing, testing, regulators, combustion air, chimneys, flues, vents, and related fuel-gas system requirements.

Exam Room Approved Books

• Uniform Mechanical Code, 2018
  Approved for use during the Nevada C-21 Refrigeration and Air Conditioning Contractor examination for applicable refrigeration, mechanical, heating, cooling, piping, ventilation, and equipment requirements.
• NFPA 54 - Standard for National Fuel Gas Code, 2012
  Approved for use during the examination for applicable natural gas piping, appliance, sizing, testing, venting, combustion-air, and fuel-system requirements.

This package focuses specifically on the books allowed into the Nevada C-21 examination. Supplemental study-only references for refrigeration theory, duct construction, load calculations, safety, solar, and evaporative cooling are not included in this exam-room package.

Test Information and Study Materials

A strong Nevada C-21 preparation plan should connect each major subject with the approved code reference most likely to support it.

Fuel Systems should receive substantial attention because this is the largest exam category. Review natural gas piping, sizing, system pressure, regulators, appliance connections, testing, shutoff requirements, combustion air, and venting. NFPA 54 should be used regularly for this portion of preparation.

Refrigerants and Refrigeration should include the refrigeration cycle, compressors, condensers, evaporators, metering devices, refrigerant behavior, pressure-temperature relationships, superheat, subcooling, and general system operation.

The Uniform Mechanical Code can support code-based refrigeration questions, but candidates should still build strong technical understanding because the code is not a substitute for knowing refrigeration fundamentals.

Piping should include materials, fittings, joining methods, supports, insulation, routing, refrigerant lines, hydronic piping, and proper installation practices. Candidates should understand how poor piping can affect pressure drop, oil return, system capacity, and equipment performance.

Ducts should include airflow, sheet-metal and flexible duct systems, supports, joints, sizing concepts, installation, leakage considerations, and coordination with air-conditioning equipment.

Load Calculations should be practiced as a technical skill. Candidates should understand the purpose of heating and cooling load calculations and how building characteristics, occupancy, internal gains, outdoor conditions, and system design influence equipment sizing.

Controls should include thermostats, relays, contactors, pressure controls, valves, dampers, sensors, and safety controls. Candidates should understand how these devices start, stop, regulate, and protect HVAC equipment.

A/C and Heat Pump Equipment should be studied as complete systems. Review compressors, coils, airflow, refrigerant movement, controls, defrost considerations, and equipment operation.

Furnaces and Heaters should include fuel supply, combustion air, burners, controls, heat exchangers, venting, and safe operation. Questions involving gas-fired equipment may require both the UMC and NFPA 54 depending on the subject.

Chimneys, Flues and Vents should be studied alongside fuel systems. Candidates should understand vent connectors, draft, clearances, terminations, appliance venting, and the safe removal of combustion products.

Combustion Air should be reviewed in relation to gas-fired appliances and equipment rooms. Candidates should understand why sufficient combustion air is required and how the code addresses openings and air supply.

Hydronics and Chillers should include pumps, valves, water flow, chilled-water distribution, heat transfer, controls, and the relationship between mechanical equipment and piping systems.

Ventilation and Exhausts should include mechanical ventilation, exhaust systems, air movement, ducts, and equipment. The Uniform Mechanical Code should be used for targeted practice involving these requirements.

Testing, Adjusting and Balancing should include airflow measurement, system performance, equipment adjustment, commissioning concepts, and recognition of conditions that can prevent proper HVAC operation.

Evaporative Cooling should include basic operation, airflow, water distribution, pads or media, and system applications. Even though supplemental evaporative-cooling references are not included in this package, candidates should prepare for the subject because it appears on the exam.

Solar also appears on the exam. Candidates should understand solar equipment applications associated with air-temperature control within the scope of the C-21 classification.

Safety should be studied independently because technical safety knowledge may be tested even when a safety reference is not available in the exam room. HVAC and refrigeration contractors may work around electrical equipment, pressurized systems, ladders, tools, fuel gas, moving machinery, and mechanical rooms.

For open-book navigation, candidates should start with the table of contents and major chapters of both approved references. Then practice using the indexes, definitions, tables, and sections that relate to commonly tested subjects.

A useful study method is to sort practice questions into two groups: UMC-based topics and NFPA 54-based topics. Once candidates become comfortable choosing the correct reference, the questions can be mixed together to simulate the real exam.

Timed practice is essential. With 85 questions in three hours, candidates should learn when a lookup is worthwhile and when it is better to answer from trade knowledge and continue.

If a code search takes too long, move forward and return later when possible. Protecting overall exam time is more important than spending several minutes on one difficult question.

How 1 Exam Prep Helps You Reach Your Goal

1 Exam Prep supports Nevada C-21 Refrigeration and Air Conditioning Contractor candidates through organized study guidance, trade-focused review, practice-oriented preparation, reference navigation, and confidence-building study structure.

This Books Allowed into Exam Package focuses specifically on the Uniform Mechanical Code, 2018 and NFPA 54, 2012, giving candidates the two references approved for use during the open-book C-21 examination.

1 Exam Prep encourages candidates to use these books throughout preparation rather than waiting until exam day. Repeated practice with chapters, indexes, definitions, tables, and major sections can make reference navigation more efficient.

Trade-focused review should connect the UMC to refrigeration, air conditioning, ventilation, hydronics, mechanical equipment, piping, chillers, and related systems. NFPA 54 should be connected to fuel-gas piping, appliances, sizing, testing, venting, and combustion air.

Practice-oriented preparation can help identify whether a missed question comes from a technical knowledge gap or difficulty locating a code section. That distinction helps candidates spend study time more effectively.

The goal is to help candidates approach the Nevada C-21 Refrigeration and Air Conditioning Contractor examination with stronger HVAC knowledge, better code-navigation skills, improved pacing, and a more organized open-book strategy without guaranteeing a passing score or licensing approval.

How many questions are on the Nevada C-21 exam?

The Nevada C-21 Refrigeration and Air Conditioning Contractor examination contains 85 questions.

How much time is allowed for the C-21 examination?

Candidates are allowed 3 hours to complete the examination.

How many correct answers are required to pass?

Candidates must answer 60 questions correctly to pass the C-21 trade examination.

Is the Nevada C-21 exam open book?

Yes. The Nevada C-21 Refrigeration and Air Conditioning Contractor examination is an open-book test.

Which books are included in this package?

This package includes the Uniform Mechanical Code, 2018 and NFPA 54 - Standard for National Fuel Gas Code, 2012.

Are both books allowed into the Nevada C-21 exam?

Yes. Both references included in this package are approved for use during the Nevada C-21 trade examination.

What does the Uniform Mechanical Code help me study?

The UMC supports refrigeration, air conditioning, heating, mechanical equipment, ducts, ventilation, piping, hydronics, chillers, furnaces, combustion air, and related mechanical code requirements.

What does NFPA 54 help me study?

NFPA 54 supports natural gas piping, sizing, regulators, appliance connections, testing, combustion air, chimneys, flues, vents, and other fuel-gas requirements.

What is the largest C-21 exam category?

Fuel Systems is the largest individual category with 10 questions.

How many Refrigerants and Refrigeration questions are on the exam?

The exam includes 7 Refrigerants and Refrigeration questions.

Does the C-21 exam include load calculations?

Yes. Load Calculations accounts for 6 questions.

Does the exam include ductwork?

Yes. Ducts accounts for 6 questions.

Does the exam include fuel-gas and venting questions?

Yes. Fuel Systems is the largest exam category, and the examination also includes Chimneys, Flues and Vents and Combustion Air.

How should I study with two open-book references?

Practice identifying whether a question belongs in the Uniform Mechanical Code or NFPA 54 before beginning a lookup. Then use timed drills to improve navigation speed.

Should I look up every answer during the exam?

No. Build strong refrigeration and air-conditioning knowledge first and use the approved books strategically when a specific code requirement, table, definition, or fuel-gas provision needs to be confirmed.

Does this package guarantee that I will pass the Nevada C-21 exam?

No. This package provides the approved exam-room references and supports organized preparation. Examination results depend on each candidate's experience, technical knowledge, study, code-navigation ability, and performance on test day.