Licensed HVAC contractor installing a heat pump and ductwork

Become a Licensed C-20 Warm-Air HVAC Contractor

The C-20 HVAC classification is built for the climate transition, heat pumps, high-efficiency systems, and the electrification of California buildings. Demand is rising fast.

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Requirements

Minimum age: 18+ is CSLB's normal applicant path. A minor may qualify only after a court appoints a guardian (BPC §7065.5)
Experience required: 4 full-time-equivalent years of journey-level experience within the past 10 years; CSLB prorates part-time work
Contractor bond: $25,000

About the Exam

Exam format: 2 parts (Law & Business + Trade)
Law & Business exam: 115 questions
School-observed scores: 65% Law / 69% Trade; not published as fixed by CSLB
Application fee: $450

License renews every 2 years. Governing code: CCR §832.20

About this classification

What does a C-20 Warm-Air HVAC contractor do?

A C-20 Warm-Air Heating, Ventilating and Air-Conditioning Contractor fabricates, installs, maintains, services, and repairs warm-air heating systems, water-heating heat pumps, ventilating systems, and air-conditioning systems, together with the ducts, registers, flues, humidity and thermostatic controls, and air filters that make them work. (Per California Code of Regulations, Title 16, §832.20.)

The C-20 is the complete comfort-cooling and warm-air-heating license. California requires a C-20 contractor for forced-air furnaces, split-system and ductless air conditioning, heat pumps, commercial rooftop units, and the full ductwork that ties them together. The scope includes solar-based warm-air, ventilation, and AC systems. The boundary to remember: comfort cooling above 50°F is C-20; refrigeration below 50°F is C-38.

Official source: CSLB C-20 classification · CSLB fee schedule Last reviewed: March 2026

Scope of work

Forced warm-air furnaces and complete duct systems
Split-system and packaged air-conditioning installation
Heat pumps, including ductless mini-splits
Water-heating heat pumps
Commercial rooftop HVAC units
Ventilation and exhaust systems
Registers, flues, and air filters
Humidity and thermostatic controls
Solar-based warm-air, ventilating, and AC systems
System maintenance, service, and repair

High-demand specialties

Heat Pumps, California's electrification push is driving a heat-pump installation wave
High-Efficiency Retrofits, Federal incentives reward upgrades to efficient systems
Ductless Mini-Splits, A fast-growing residential and ADU solution
Commercial Rooftop Units, Steady service-and-replace work on existing buildings

Important notes

A C-20 contractor installs the furnace and ducts but cannot run gas piping from the meter to the structure (CCR §832.36(d), no exception). For the appliance-level connection itself, C-36's gas-appliance-connection grant explicitly excludes forced warm-air units (CCR §832.36(c)), so it is not exclusively C-36 territory the way it is for other heating appliances.
The C-20 covers comfort cooling above 50°F. Walk-in coolers, ice machines, refrigerated display cases, and cold-storage systems maintained below 50°F require a C-38 (Refrigeration) license.
Boilers, hydronic (hot-water) heating, and steam fitting fall under the C-4, the C-20 covers forced warm-air systems, not water-based heating.
A standalone ductwork-only contractor may operate under a C-43 (Sheet Metal); the C-20 covers the complete HVAC system, not just the ducts.
Any HVAC project over $1,000 requires a licensed contractor. California also requires workers' compensation coverage for licensees.

The CSLB exam

What's on the C-20 Warm-Air HVAC exam?

California requires you to pass a two-part CSLB exam: the Law & Business exam (the same for every classification) and the C-20 Warm-Air HVAC trade exam. CSLS has observed scores of 65% for Law & Business and 69% for the C-20 trade exam. CSLB does not publish fixed passing scores and may vary them by exam version.

Law & Business

Same for all classifications

115 questions, multiple choice, computer-based
3.5 hours allotted
Topics: California contractor law, business management, safety, estimating, project management

C-20 Trade Exam

Warm-Air HVAC-specific

about 115 questions, multiple choice, computer-based
3.5 hours allotted
Topics: heating and cooling theory, load calculations, duct design, refrigerant cycle, controls, ventilation, mechanical code, system service

How to Get Your C-20 Warm-Air HVAC License

Step 1

Qualify

18+ is CSLB's normal applicant path. A minor may qualify only after a court appoints a guardian (BPC §7065.5). You also need a valid SSN/ITIN and 4 full-time-equivalent years of journey-level warm-air heating, ventilating, and air-conditioning experience within the past 10 years; CSLB prorates part-time work. Up to 3 years may be substituted with approved education or apprenticeship.

Step 2

Apply to CSLB

Submit your application, get fingerprinted, and pay the $450 application fee. Processing times vary; check the CSLB's current processing times.

Step 3

Study & Prepare

Prepare for both exam parts, on your own or with a CSLS exam prep program. 99% of CSLS students pass on their first try, backed by our 100% Money-Back Guarantee.

Compare programs

Step 4

Pass the Exam

Two parts: Law & Business (115q, 3.5 hrs) + C-20 Trade. Multiple choice, computer-based. CSLS has observed scores of 65% Law & Business / 69% C-20 Trade; CSLB does not publish fixed passing scores and may vary them by exam version.

Step 5

Get Licensed

Post your $25,000 contractor bond, pay the $200 license fee, and receive your C-20 license. You're officially in business.

Step 1

Qualify

Step 2

Apply to CSLB

Submit your application, get fingerprinted, and pay the $450 application fee. Processing times vary; check the CSLB's current processing times.

Step 3

Study & Prepare

Prepare for both exam parts, on your own or with a CSLS exam prep program. 99% of CSLS students pass on their first try, backed by our 100% Money-Back Guarantee.

Compare programs

Step 4

Pass the Exam

Step 5

Get Licensed

Post your $25,000 contractor bond, pay the $200 license fee, and receive your C-20 license. You're officially in business.

Career outlook

Why get your C-20 Warm-Air HVAC license?

~$68,000

Mean CA Wage (BLS)

Projected Job Growth

$70K–$150K+

Owner Income Range

99%

CSLS First-Time Pass Rate

The electrification opportunity

HVAC is one of the fastest-changing trades in California. The state's push toward building electrification, heat-pump adoption, and high-efficiency systems, reinforced by federal incentives, is creating years of installation and retrofit work. Contractors who specialize early in heat pumps are positioned for a long demand cycle.

A multi-license strategy

Many HVAC pros widen their scope by pairing the C-20 with a C-38 (Refrigeration) to take cold-storage and commercial-refrigeration work, or a C-36 (Plumbing) to run their own gas lines. Stacking complementary licenses lets you bid complete mechanical jobs instead of subbing out pieces.

Strong, climbing wages

HVAC technicians in California earn a mean wage near $68,000 (BLS), and pay runs well above that in the Bay Area, where field rates can exceed $39 per hour versus roughly $33 statewide. Licensed C-20 contractors running their own businesses commonly earn $70,000 to $150,000 or more. The license is required for jobs over $1,000, protecting your access to larger contracts.

C-20 vs. C-38: above or below 50°F

The dividing line is temperature. The C-20 covers comfort cooling and warm-air heating for spaces above 50°F. The C-38 (Refrigeration) covers walk-in coolers, freezers, ice machines, refrigerated cases, and cold-storage systems maintained below 50°F. If you want both comfort cooling and commercial refrigeration, you'll want both licenses.

Wage data: U.S. Bureau of Labor Statistics (OES) and California EDD.

Exam Prep Programs

Compare C-20 Warm-Air HVAC Exam Prep Programs

Every program prepares you for the required CSLB exam for C-20 Warm-Air HVAC. Our 99% first-time pass rate is backed by the 100% Money-Back Guarantee on eligible programs.

Feature-by-feature comparison of all four CSLS exam prep programs
Features	Most Popular All-Inclusive C-20 Warm-Air HVAC $1,195.00 Value: $2,500	Live Online C-20 Warm-Air HVAC $695.00 Value: $995	Crash Course C-20 Warm-Air HVAC $495.00 Value: $695	Home Study C-20 Warm-Air HVAC $295.00 Value: $395
Best For	Comprehensive prep with maximum support	Remote learners wanting live instruction	Experienced pros with an exam date soon	Self-directed independent learners
Law & Business Classes	4 Classes + Full-Day Review	4 Live Online + Review	Full-Day Review Only	Not included
Trade Math Training	30-Day Interactive + Review	Online Video Review	14-Day Crash Course	Not included
Test-Taking Skills Seminar	1-Day In-Person	1-Day Online	Not included	Not included
Law & Business Materials	Online; binder add-on available	Online; binder add-on available	Online; binder add-on available	Online; binder add-on available
Trade-Specific Materials	Online; binder add-on available	Online; binder add-on available	Online; binder add-on available	Online; binder add-on available
Study Materials	Full Online Suite	Online Materials + Audio/Video	Online + Audio/Video	Online + Audio
Online Videos	Full Suite: L&B, Trade, H&S, Math	Audio + H&S + Math Videos	Audio + H&S + Math Videos	L&B Audio + H&S Video
Law & Business Practice Exams	6 Months	2 Months	30 Days	30 Days
Trade Practice Exams	6 Months	2 Months	30 Days	30 Days
School Location Access	25+ Locations	25+ Locations	25+ Locations	Self-Study Only
Application Assistance	Preparation & Review	Review Only	Review Only	Not included
Money-Back Guarantee	Included	Included	Included	Not included
Bond Fee Discount	50% off first-year bond, up to $120	Not included	Not included	Not included
Retail Value	$2,500	$995	$695	$395
Choose a program	Get All-Inclusive	Get Live Online	Get Crash Course	Get Home Study

Not sure which fits? Call 800-809-6463. Prices and inclusions are subject to change.

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What our Warm-Air HVAC students say

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Common Questions

C-20 Warm-Air HVAC license FAQ

Plan on 2–4 months from application to license-in-hand. That includes CSLB processing (typically 2–4 weeks), scheduling and passing both exams, and posting your $25,000 bond. With CSLS exam prep, most students are exam-ready in 4–6 weeks.

4 full-time-equivalent years of journey-level warm-air heating, ventilating, and air-conditioning experience within the past 10 years; CSLB prorates part-time work. Qualifying work may be as a journeyperson, foreperson, supervising employee, contractor, or owner-builder. Up to 3 years can be satisfied with approved apprenticeship, technical training, or education. Keep documentation, CSLB verifies the experience you claim.

Temperature is the dividing line. A C-20 (HVAC) contractor handles comfort cooling and warm-air heating for spaces kept above 50°F, furnaces, AC, and heat pumps. A C-38 (Refrigeration) contractor handles systems maintained below 50°F: walk-in coolers, freezers, ice machines, refrigerated display cases, and cold-storage warehouses. Many contractors hold both to cover comfort cooling and commercial refrigeration.

The C-20 covers the warm-air furnace, ducts, registers, flues, and controls. Running gas piping from the meter to the structure is always C-36 (Plumbing) scope (CCR §832.36(d)), but C-36's gas-appliance-connection grant specifically excludes forced warm-air units (CCR §832.36(c)), so the appliance-level connection isn't exclusively C-36 territory here. Many HVAC contractors either hold a C-36 as well or coordinate with a licensed plumber for the gas connection.

Budget about $885 minimum before exam prep: $450 for the application (both exams), $200 for initial license issuance, roughly $150 for your first year of $25,000 bond premium, and about $85 for fingerprinting. The bond is a premium, not cash you tie up.

The C-20 trade exam is computer-based and covers heating and cooling theory, load calculations, duct design, the refrigerant cycle, controls, ventilation, and the mechanical code. You need the current version-specific CSLB passing score to pass. With CSLS exam prep, 99% of students pass on their first attempt, backed by our 100% Money-Back Guarantee.

HVAC technicians in California earn a mean wage near $68,000 (BLS), with higher pay in the Bay Area and other high-cost metros. Licensed C-20 contractors running their own businesses typically earn $70,000 to $150,000 or more. Specializing in heat pumps and high-efficiency retrofits can push earnings higher as demand grows.

CSLB evaluates reciprocity case-by-case (BPC §7065.4) and may waive the trade exam if your out-of-state license has been in good standing for the past five years; CSLB names no fixed list of reciprocal states. If you hold an equivalent active HVAC license in one of those states, your C-20 trade exam may be waived, but you still must pass the California Law and Business exam and satisfy the remaining requirements.

Since 1985

40+ Years

200,000+

Students Licensed

99% Pass Rate

First-Time

100% Money-Back Guarantee

Tuition Refund

Become a Licensed C-20 Warm-Air HVAC Contractor

What does a C-20 Warm-Air HVAC contractor do?

Scope of work

High-demand specialties

Important notes

What's on the C-20 Warm-Air HVAC exam?

Law & Business

C-20 Trade Exam

How to Get Your C-20 Warm-Air HVAC License

Qualify

Apply to CSLB

Study & Prepare

Pass the Exam

Get Licensed

Qualify

Apply to CSLB

Study & Prepare

Pass the Exam

Get Licensed

Why get your C-20 Warm-Air HVAC license?

The electrification opportunity

A multi-license strategy

Strong, climbing wages

C-20 vs. C-38: above or below 50°F

Compare C-20 Warm-Air HVAC Exam Prep Programs

Labor Day Promo 2026

What our Warm-Air HVAC students say

Try a free C-20 Warm-Air HVAC practice exam

C-20 Warm-Air HVAC license FAQ

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