About this C-20 — HVAC prep
This prep is built specifically for the C-20 — HVAC examination and includes a 18,000+-word study guide written for this exam, 5 full-length practice exams and 504 practice questions, each with a written explanation.
The CSLB C-20 Warm-Air Heating, Ventilating and Air-Conditioning trade examination is administered by CSLB / PSI. Closed book 3.5 hours. CSLB does not publish scored Q or pass %. Practice 5×100/210. Mix (on/after 4/1/2026): Planning 22, Fabrication 38, Troubleshooting 20, Safety 20. Law separate.. This prep is written to that board’s current scope, not to a generic national syllabus.
The real C-20 — HVAC exam contains 100 questions. Our practice exams mirror that structure so the format is familiar before you sit it.
Topics covered
- Duct Design and Installation
- 5 - Heating Design Temperature (ACCA Manual J)
- Additional Business Requirements
- System Types -- Additional Details
- Additional Calculation Practice
- 2 - Air Filter MERV (ASHRAE 52.2)
- Title 24 Part 6 -- Energy Efficiency Requirements
- EPA 608 Certification (Business Requirement)
- Types of HVAC Systems
- Zoning Systems
- California Mechanical Code (CMC) -- Title 24 Part 4
- Electrical Requirements for HVAC (CEC/NEC)
- Refrigeration Systems (CMC Chapter 11)
- The Refrigeration Cycle
- Electrical Troubleshooting for HVAC
- System Commissioning and Startup
- Thermostat Wiring and Controls
- Refrigerant Charging Procedures
- 1 - Occupancy-Based Controls (ASHRAE 90.1)
- 5-hour closed-book protocol
How access works
You are paying for access length (30, 60, or 90 days). The study guide and four timed exams are the same on every term. Access starts when you enrol and works on any device for that term.
Not affiliated with or endorsed by any state licensing board or exam vendor. For exam-preparation purposes only.
What is actually on the C-20 exam
CSLB divides the Warm-Air Heating, Ventilating and Air-Conditioning (C-20) examination into four sections. These weightings are the Board’s own, taken from the study guide it publishes for this classification — they are not our estimate:
| Section | Share of exam |
|---|---|
| Planning and Estimating | 22% |
| Fabrication, Installation, and Startup | 38% |
| Troubleshooting, Repair, and Maintenance | 20% |
| Safety | 20% |
The C-20 examination is closed book — no reference materials may be used during the test. Questions are multiple choice with four options, and there is no penalty for guessing, so leave nothing blank.
This is only half of what you sit. Every applicant also passes the separate Law and Business examination, which is not part of the C-20 paper and is weighted on its own outline. Budget preparation time for both.
Source: CSLB Warm-Air Heating, Ventilating and Air-Conditioning (C-20) examination study guide. Contractor Pathway is an independent exam-preparation provider and is not affiliated with or endorsed by CSLB.