- What This Cheat Sheet Covers
- NV-C21 Format at a Glance
- Registration, Fees and Eligibility Snapshot
- Domain Weights Ranked by Item Count
- Approved References and What You Can Bring
- High-Value Topics Inside Each Heavy Domain
- Calculator, Tabs and What Gets You Disqualified
- Retake Rules and the 30-Day Reapplication Clock
- Final Week Review Sequence
- FAQ
- The trade exam is 85 questions in 180 minutes; you need 60 correct to pass.
- Fuel Systems (10 items) and Refrigerants and Refrigeration (7 items) carry the most weight of the 22 domains.
- Only the 2018 Uniform Mechanical Code and NFPA 54 (2012) may be used as open-book references.
- Trade-only registration is $95; adding the Construction Management Survey brings it to $140.
What This Cheat Sheet Covers
This is a compressed, one-page-style reference for the Nevada C-21 Refrigeration and Air Conditioning Contractor Trade Exam (NV-C21), administered through PSI Services LLC under Nevada State Contractors Board oversight. It is not a substitute for full domain review - for that, see the NV-C21 Study Guide 2026 or the domain-by-domain breakdown in the NV-C21 Exam Domains 2026 guide. Instead, treat this page as the facts you should be able to recall cold the night before your test date, or the sheet you skim during a lunch break the week of the exam.
Every number below traces back to the PSI candidate bulletin (last updated March 25, 2026) and Nevada State Contractors Board licensing pages. If you want the deeper "why" behind any fact here, the linked articles on this site go further into each topic.
NV-C21 Format at a Glance
The trade portion of NV-C21 is a computer-based, multiple-choice exam delivered at a PSI test center once the Board has approved your application and issued an eligibility notice. Here's the shape of the test itself:
- Total questions: 85
- Time allowed: 180 minutes
- Passing score: 60 correct answers
- Format: multiple-choice, computer-based
- Unscored items: PSI may insert 1-10 experimental questions that are unscored but still count against your time
That last point matters more than most candidates realize. You cannot identify which questions are experimental, so pacing has to account for up to 95 total questions inside the same 180-minute window even though only 85 count. For a full breakdown of what "passing" actually requires numerically, see NV-C21 Passing Score 2026.
Key Takeaway
Budget roughly two minutes per question, not per scored item - the experimental questions eat real clock time even though they don't count toward your 60-correct threshold.
Registration, Fees and Eligibility Snapshot
Money and eligibility details trip up more candidates than the technical content does. Here's the mechanics in one place:
| Item | Detail |
|---|---|
| Trade exam only | $95 |
| Trade + Construction Management Survey | $140 |
| License application fee | $300 |
| Biennial license fee | $600 |
| Experience required | 4 years journeyman, foreman, supervising-employee, or contractor experience within the preceding 15 years |
| Education substitution | Approved education can replace up to 3 of the 4 required years |
Along with the exam fee, expect an experience verification review, a financial and background review, and license bond and insurance requirements before a license is issued. The Construction Management Survey is a separate business-and-law exam that's normally required unless waived, and it carries its own passing standard - it is not scored together with the C-21 trade exam. For the complete cost picture including renewal cycles, see NV-C21 Certification Cost 2026, and for the eligibility path in full detail, check NV-C21 Requirements 2026.
Domain Weights Ranked by Item Count
NV-C21 covers 22 distinct content domains across the 85 scored questions. Here is the official item allocation, ordered by weight so you can see where study time pays off fastest:
| Domain | Items |
|---|---|
| Fuel Systems | 10 |
| Refrigerants and Refrigeration | 7 |
| Piping | 6 |
| Load Calculations | 6 |
| Ducts | 6 |
| Heating and Cooling Principles | 5 |
| Chimneys, Flues and Vents | 5 |
| Sound, Vibration and Seismic Control | 4 |
| A/C and Heat Pump Equipment | 4 |
| Furnaces and Heaters | 4 |
| Solar | 4 |
| Ventilation and Exhausts | 4 |
| Hangers and Supports | 3 |
| Testing, Adjusting and Balancing | 3 |
| Evaporative Cooling | 3 |
| Chillers | 3 |
| Safety | 4 |
| Insulation | 1 |
| Controls | 1 |
| Machine Room | 1 |
| Hydronics | 2 |
| Combustion Air | 2 |
That's 22 domains totaling 85 items. Fuel Systems alone is larger than the bottom five domains combined - a fact worth internalizing before you build a study schedule. For narrative detail on what each domain actually tests, the NV-C21 Exam Domains 2026 article walks through all 22 in order.
Fuel Systems (10 items - largest domain)
This domain drives the requirement to bring NFPA 54 National Fuel Gas Code (2012) into the exam. Expect questions on gas piping sizing, appliance connections, venting interaction with fuel-burning equipment, and code-referenced installation clearances.
- Practice locating specific tables and sections in NFPA 54 quickly - speed with the reference document matters as much as knowing the content
- Cross-reference fuel system questions against Chimneys, Flues and Vents and Combustion Air, since real installations tie these together
Refrigerants and Refrigeration (7 items - second largest)
Covers refrigerant properties, cycle behavior, recovery and handling practices, and equipment-specific refrigeration concepts tested against the Uniform Mechanical Code.
- Know pressure-temperature relationships and basic cycle diagrams cold
- Expect overlap with Machine Room and Chillers content even though those are smaller domains individually
Approved References and What You Can Bring
NV-C21 is open book, but the list of allowed references is short and strictly enforced:
- 2018 Uniform Mechanical Code
- NFPA 54 National Fuel Gas Code (2012)
No other codebooks, printed notes, or third-party study guides are permitted at the testing station. Within those two approved books, you are allowed to pre-highlight, underline, and add permanent tabs before test day. What is not allowed: handwritten notes inside the books, temporary/removable tabs, or any loose inserted material such as sticky notes with written content.
Because Fuel Systems is the single largest domain, your NFPA 54 tabbing and highlighting should get proportionally more attention than any other section of either code book. If you're unsure how heavily to weight code-navigation practice against pure recall, How Hard Is the NV-C21 Exam? breaks down where candidates typically lose time.
High-Value Topics Inside Each Heavy Domain
Beyond Fuel Systems and Refrigerants and Refrigeration, three more domains deserve focused attention because they each carry 6 items - Piping, Load Calculations, and Ducts.
Piping (6 items)
Material selection, joining methods, sizing logic, and support spacing as referenced in the Uniform Mechanical Code. Overlaps with Hangers and Supports (3 items) and Hydronics (2 items).
- Know which pipe materials are code-approved for which refrigerant or fuel application
Load Calculations (6 items)
Sizing logic tied to Heating and Cooling Principles (5 items). Expect scenario-based questions rather than pure definition recall.
- Practice working through calculation steps under time pressure, not just recognizing formulas
Ducts (6 items)
Sizing, material, and installation requirements that intersect with Ventilation and Exhausts (4 items) and Sound, Vibration and Seismic Control (4 items).
- Watch for questions that combine duct sizing with seismic bracing requirements - these span two domains in a single question
Together these five domains - Fuel Systems, Refrigerants and Refrigeration, Piping, Load Calculations, and Ducts - account for 35 of the 85 scored questions. That's over 40% of your score sitting in five of twenty-two domains.
Calculator, Tabs and What Gets You Disqualified
A silent, non-programmable calculator is allowed, provided it meets PSI's testing-center restrictions. Bring a simple model - anything with text-storage, graphing, or programmable functions risks being confiscated at check-in, which forces you to work without one.
Combine this with the reference-material rules above and the picture is clear: NV-C21's open-book format is generous on code access but strict on what counts as "preparation" versus "smuggled content." Handwritten annotations, loose paper, and temporary tabs are treated the same as unauthorized materials.
Key Takeaway
Set up your two approved code books - permanent tabs and pre-highlighting only - at least a week before your test date, then rehearse navigating them under a timer so lookup speed becomes automatic.
Retake Rules and the 30-Day Reapplication Clock
If you don't pass on your first attempt, Nevada's retake structure works like this:
- You must wait two weeks before your next attempt
- After three failed attempts, your application is voided
- You may reapply only after 30 days from the voided application
This structure rewards a deliberate, domain-weighted study plan over a rush-and-retake approach. Two failed attempts spaced two weeks apart, followed by a rushed third attempt, is a slower path than spending those same weeks working through the heaviest domains systematically. For a realistic sense of how attempts typically go, see NV-C21 Pass Rate 2026: What the Data Shows.
Final Week Review Sequence
A single week's structured review, built around NV-C21's actual weighting, looks different from a generic study calendar:
Fuel Systems and NFPA 54 navigation
- Re-tab and re-highlight NFPA 54 sections tied to gas piping and appliance venting
- Time yourself locating five random Fuel Systems topics inside the code book
Refrigerants and Refrigeration plus Machine Room
- Review pressure-temperature relationships and recovery procedures
- Connect refrigeration cycle concepts to Chillers content
Piping, Load Calculations, Ducts
- Work through sizing scenarios rather than just definitions
- Cross-check Uniform Mechanical Code tabs against these three domains
Mid-weight domains sweep
- Heating and Cooling Principles, Chimneys/Flues/Vents, Sound/Vibration/Seismic Control, A/C and Heat Pump Equipment
- Quick-fire review, no deep dives - these carry 4-5 items each
Low-weight domains and Safety
- Insulation, Controls, Machine Room, Hydronics, Combustion Air - 1-2 items each but still scored
- Full Safety domain review
Full timed run-through
- Simulate 180 minutes across a mixed 85-question set
- Practice with your actual tabbed code books, not clean copies
Note that this sequence deliberately front-loads Fuel Systems and Refrigerants and Refrigeration because they represent 17 of 85 items combined - roughly one-fifth of the entire scored exam concentrated in two domains. For a longer-horizon plan that starts weeks or months out instead of one week, the NV-C21 Study Guide 2026 lays out a full-length approach.
Who This Exam Serves and Why the Details Matter
NV-C21 exists to license refrigeration and air conditioning contractors under Nevada State Contractors Board rules, and the trade content reflects what a working C-21 licensee actually needs on the job - code-compliant fuel gas connections, correct refrigerant handling, accurate load and duct sizing, and seismic-aware installation practices. If you're still confirming what the license itself represents before diving into cheat-sheet mechanics, What Is NV-C21? and NV-C21 Certification cover the basics, while NV-C21 Jobs and Is the NV-C21 Certification Worth It? address the practical payoff of holding the license.
For hands-on practice against realistic question formats before test day, run through timed sets on the main NV-C21 practice test platform - it's a faster way to find weak domains than reading alone. You can return to the practice site homepage anytime to pick a domain-specific set that matches wherever this cheat sheet exposed a gap.
FAQ
85 scored questions in 180 minutes, with a passing threshold of 60 correct. PSI may add up to 10 additional unscored experimental questions that still consume exam time.
Only the 2018 Uniform Mechanical Code and the NFPA 54 National Fuel Gas Code (2012). Pre-highlighting, underlining, and permanent tabs are allowed; handwritten notes, temporary tabs, and loose inserted material are not.
The trade exam alone is $95. Adding the Construction Management Survey business-and-law package brings it to $140. Separately, licensing involves a $300 application fee and a $600 biennial license fee.
Three failed attempts void your application. You must wait 30 days from the voided application before reapplying. Between individual attempts, the wait is two weeks.
Fuel Systems (10 items) and Refrigerants and Refrigeration (7 items) carry the most weight, followed by Piping, Load Calculations, and Ducts at 6 items each. Together these five domains cover 35 of the 85 scored questions.