学习材料
用通俗易懂的方式掌握考试的每个主题。
Equipment Installation: Scope, Placement, Clearances, and Access
CSLB publishes an official study guide for the C-20 examination, and its largest content area by far is Fabrication, Installation, and Startup at roughly 38 percent, followed by Planning and Estimating at about 22 percent, Troubleshooting, Repair, and Maintenance at about 20 percent, and Safety at about 20 percent. PrepPass groups its practice bank slightly differently, into five topics, and installation is the largest of them at about 27 percent of our bank. Because installation is so heavily weighted, this guide splits it across four chapters. This first one covers the boundary of the C-20 license itself, the system types you will be asked to distinguish, and the rules that govern where a piece of equipment may physically sit: orientation, clearance to combustible construction, and the access a service technician must be given after you leave. Get these right and a large block of installation questions becomes straightforward, because almost all of them are asking the same underlying question in different words: is this unit safe to run and possible to service?
Combustion Air, Venting, and Condensate
This is the part of installation that kills people when it is done wrong, which is why the exam returns to it so often. Every gas-fired appliance needs a supply of air to burn and a reliable path for the products of combustion to leave the building, and a condensing appliance adds a third stream, liquid condensate, that has to be drained. This chapter works through all three. It is the second of four installation chapters, and the topic as a whole is about 27 percent of the practice bank. Where a specific dimension is stated below, it comes from the California Mechanical Code, Title 24 Part 4, and you should confirm it against the edition your jurisdiction has adopted; California is on a three-year code cycle and the 2025 edition took effect for permits applied for on or after January 1, 2026.
Refrigerant Line Sets, Evacuation, and Charging
Everything between the outdoor unit's service valves and the indoor coil is your work, and it is unforgiving. A line set that is one size too small, a braze made without nitrogen, or a system charged on top of a shallow vacuum will run for a season and then fail in a way that looks like a compressor problem. This chapter, the third of four on installation, covers sizing the piping, brazing it cleanly, proving it does not leak, evacuating it properly, and putting the correct amount of refrigerant in it. The commissioning arithmetic of superheat and subcooling is developed further in the refrigeration chapters; here we focus on the installation sequence and the mistakes that get built into a system on day one.
Ductwork, Gas Piping, Electrical, and Startup
The official CSLB outline calls this content area Fabrication, Installation, and Startup, and startup is the word candidates skip. A system is not installed when the last screw goes in; it is installed when the temperature rise is inside the range on the rating plate, the manifold pressure is where the manufacturer wants it, the static pressure is survivable, and the charge has been verified. This chapter, the last of four on installation, covers the three trades that meet at the equipment, sheet metal, gas piping, and electrical, and then the startup readings that prove the job.
Load Calculation: Manual J and the Arithmetic Behind It
CSLB's official outline puts Planning and Estimating at roughly 22 percent of the C-20 examination, and it explicitly lists HVAC system design and evaluation, load and psychrometric calculations, duct system design and layout, and job cost estimation. The exam is a closed-book, multiple-choice test with four choices per question, and some questions require mathematical computation; a calculator is provided. This chapter covers the load side of that content area, with the arithmetic worked out rather than asserted. The next chapter covers equipment selection, duct design, estimating, and the California Energy Code requirements that attach to both.
Equipment Selection, Duct Design, Estimating, and Title 24
Once the load is known, three things follow: which piece of equipment to buy, how to get the air where it has to go, and what to charge. This chapter covers Manual S selection, Manual D duct design with the arithmetic worked, ventilation and air-change calculations of the kind CSLB prints as a sample question, job cost estimating, and the California Energy Code requirements that attach to duct systems. Together with the previous chapter this is the Planning and Estimating content area, roughly 22 percent of the official CSLB outline.
The Refrigeration Cycle, Superheat, and Subcooling
Refrigeration questions are about 20 percent of the practice bank, and they split cleanly into two halves. This chapter is the physics: what each component does, what saturation means, and how to calculate and interpret superheat and subcooling, which are the two numbers that tell you almost everything about a running system. The next chapter is the regulatory and handling half, covering refrigerant types, blends, and EPA Section 608. Almost every troubleshooting question later in the guide resolves back to a superheat or subcooling reading, so this is the chapter to be fluent in.
Refrigerants, Recovery, and EPA Section 608
Handling refrigerant is federally regulated work, and unlike most of what this exam covers, the rules come from Washington rather than Sacramento. Section 608 of the Clean Air Act and its implementing regulations at 40 CFR Part 82, Subpart F, govern who may service equipment containing regulated refrigerant, what must be done before a system is opened, and how refrigerant may be reused or disposed of. This chapter also covers the current refrigerant transition, which is the single fastest-changing area in the trade, so treat specific product names and dates as things to verify rather than memorize.
Service, Troubleshooting, and Efficiency
The official CSLB outline calls this content area Troubleshooting, Repair, and Maintenance and puts it at roughly 20 percent of the examination. Troubleshooting questions are written as short scenarios: a set of symptoms and readings, and four candidate causes. The way to answer them reliably is not to memorize scenarios but to know what each measurement can and cannot distinguish. This chapter organizes the material that way, starting with the electrical side, then the gas furnace sequence of operation, then the airflow-versus-charge problem that underlies most no-cooling calls, and finally the efficiency ratings and the customer conversations that go with them.
Safety, Cal/OSHA, Codes, and Licensing Law
Safety is roughly 20 percent of the official CSLB C-20 outline, listed as personal protective equipment, job site safety requirements under Cal/OSHA, and handling hazardous materials. This chapter covers those, the California codes that govern the work, and the licensing law that governs the business. The licensing questions here overlap with the separate Law and Business examination that every applicant also has to pass, so the effort is not wasted. Where a code section is named below it is named deliberately; where a figure could have moved between code editions or legislative sessions, the passage says so instead of pinning a number.
按主题练习
Jump straight into free practice questions for any single CSLB HVAC (C-20) Trade content area.
