Pass the California
C-20 HVAC
License Exam
Built directly from the official CSLB C-20 Study Guide. Four exam sections, 120+ real-style questions, formula calculators, flashcards, code references, and a 10-week study plan — everything you need to pass the first time.
~100
Exam Questions
3 HRS
Time Allowed
70%
Passing Score
CLOSED
Book Policy
📊 Exam Section Weights
Know where to focus your study time:
📚 Key CSLB Exam Rules
4 Choices — 1 BEST Answer
Read all four options before selecting. CSLB writes distractors that are partially correct — you need the BEST answer, not just a correct one.
No penalty for guessing — always fill in every question.
A calculator is provided at the testing center for math questions.
CLOSED BOOK — no notes, books, or phones allowed during the exam.
🔑 Reference Codes Used to Write the C-20 Exam
2022 CA Mechanical Code
Primary code for HVAC systems. IAPMO. Title 24. Duct sizing, equipment installation, combustion air.
2022 CA Energy Code
HVAC efficiency requirements, duct sealing, insulation, Title 24 Part 6 compliance.
2022 Building Energy Efficiency Stds
CEC residential & nonresidential HVAC efficiency mandates. SEER2, EER2 minimums.
ASHRAE Handbooks
Fundamentals, HVAC Applications, Systems & Equipment. Load calcs, psychrometrics.
ACCA Manuals J, D, S, N
Manual J = residential load calc. Manual D = duct design. Manual S = equipment selection.
Cal/OSHA Title 8
Safety orders for all HVAC work. Confined space, refrigerant handling, electrical.
SMACNA Duct Standards
Metal & flexible duct construction, leakage classes, pressure ratings.
2022 CA Electrical Code
Disconnect sizing, GFCI, equipment grounding for HVAC electrical connections.
2022 CA Plumbing Code
Condensate drainage, refrigeration piping, hydronic systems overlap.
📊 CSLB C-20 EXAM STRUCTURE
Exam Overview
The C-20 Exam is divided into four major sections — each weighted by percentage. Your study time should mirror these weights.
01
Planning & Estimating
25%
- HVAC system design and evaluation
- Load and psychrometric calculations
- Duct system design and layout
- Job cost estimation
02
Fabrication, Installation & Startup
29%
- Duct system fabrication (SMACNA)
- Equipment installation
- Electrical and mechanical components
- Plumbing and refrigeration components
- Air distribution and duct systems
- HVAC system startup
03
Troubleshooting, Repair & Maintenance
24%
- HVAC system diagnostic tests and evaluation
- HVAC system maintenance and repair
04
Safety
22%
- Personal protective equipment (PPE)
- Job site safety requirements (Cal/OSHA)
- Handling hazardous materials
🗓 Exam Day — What to Expect
Format
- Multiple-choice, 4 options per question
- One BEST answer only
- Some questions require math computation
- Calculator provided — no personal calculators
- No penalty for guessing — always answer
Logistics
- Administered at PSI testing centers statewide
- Closed-book — no reference materials
- Must also pass the Law & Business Exam
- Government-issued photo ID required
- Questions written by active licensed C-20 contractors
The three official CSLB sample questions are included in this course's quiz — EER calculation, thermocouple function, and water-source heat pump components. These confirm the real exam question style.
SECTION 1 — 25% OF EXAM
Planning & Estimating
Covers HVAC system design and evaluation, load and psychrometric calculations, duct system design and layout, and job cost estimation.
🏠 HVAC System Design & Evaluation
The C-20 contractor must be able to design, evaluate, and select HVAC systems appropriate for the building type, climate zone, and occupancy. California has 16 climate zones — equipment selection and efficiency requirements vary by zone.
- Heating systems: forced-air furnaces, heat pumps, radiant systems, boilers
- Cooling systems: split systems, package units, VRF, evaporative coolers
- System types: single-zone, multi-zone, VAV (Variable Air Volume), constant volume
- Right-sizing is critical: oversized equipment short-cycles (reduces comfort, increases humidity); undersized can't meet design conditions
Equipment sizing is always based on Manual J load calculation — never on square footage alone. This is a commonly tested concept.
ACCA Manual J — Residential Load Calculation. ACCA Manual N — Commercial Load Calculation.
🌡 Load Calculations — Manual J
The heating and cooling load determines equipment sizing. Key factors:
- Sensible heat: dry heat — changes air temperature (BTU/hr)
- Latent heat: moisture — changes humidity (BTU/hr)
- Total load = Sensible + Latent
- Conduction gains/losses: through walls, roof, windows, floors (U-value × Area × ΔT)
- Solar gain: through glazing — SHGC (Solar Heat Gain Coefficient) × window area × solar factor
- Infiltration and ventilation: outside air load must be added to envelope load
- Internal gains: people (250 BTU/hr sensible, 200 BTU/hr latent), lighting, equipment
Conduction Load: Q = U × A × ΔT
Q = heat flow (BTU/hr)
U = overall heat transfer coefficient (BTU/hr·ft²·°F)
A = surface area (ft²)
ΔT = temperature difference (inside – outside, °F)
Example: Wall, U=0.08, 200 ft², ΔT=30°F
Q = 0.08 × 200 × 30 = 480 BTU/hr
Q = heat flow (BTU/hr)
U = overall heat transfer coefficient (BTU/hr·ft²·°F)
A = surface area (ft²)
ΔT = temperature difference (inside – outside, °F)
Example: Wall, U=0.08, 200 ft², ΔT=30°F
Q = 0.08 × 200 × 30 = 480 BTU/hr
ASHRAE Fundamentals — Heat transfer calculations. ACCA Manual J — Residential loads.
📊 Psychrometrics — The HVAC Science
Psychrometrics describes the properties of moist air. The psychrometric chart is a key tool — know these properties:
- Dry-bulb temperature (DB): air temperature measured by a standard thermometer
- Wet-bulb temperature (WB): temperature of adiabatic saturation — indicates evaporation potential
- Dew point: temperature at which moisture begins to condense (100% RH)
- Relative humidity (RH): ratio of actual moisture to maximum possible at that temperature
- Specific humidity (humidity ratio): grains of water vapor per pound of dry air (gr/lb)
- Enthalpy: total heat content of air (BTU/lb of dry air) — includes sensible + latent
- Sensible Heat Ratio (SHR): sensible load ÷ total load — used to plot process on psych chart
EER = BTU/hr of cooling ÷ Watts of electrical input
(Official CSLB Sample: 24,000 ÷ 2,400 = EER of 10.0 ✓)
COP (Coefficient of Performance):
COP = BTU output ÷ BTU input (heat pumps)
COP = EER ÷ 3.412
SEER2 = Seasonal Energy Efficiency Ratio (newer standard)
California min: 15 SEER2 (most residential split systems, 2023+)
(Official CSLB Sample: 24,000 ÷ 2,400 = EER of 10.0 ✓)
COP (Coefficient of Performance):
COP = BTU output ÷ BTU input (heat pumps)
COP = EER ÷ 3.412
SEER2 = Seasonal Energy Efficiency Ratio (newer standard)
California min: 15 SEER2 (most residential split systems, 2023+)
ASHRAE Manual P — Psychrometrics. ACCA Manual RS — Comfort, Air Quality & Efficiency by Design.
🌀 Duct System Design — Manual D
Duct design determines airflow delivery to each zone. The equal friction method and velocity reduction method are the two primary approaches:
- Equal friction method: design all duct sections at the same friction rate (typically 0.1 in.w.g. per 100 ft)
- Static pressure: the driving force for air movement — measured in inches water gauge (in.w.g.)
- Total external static pressure (TESP): maximum resistance the blower must overcome
- CFM (cubic feet per minute): airflow — approximately 400 CFM per ton of cooling (residential)
- Duct sizing: larger duct = lower velocity = less pressure drop = quieter operation
- Return air: must be sized to handle 100% of supply airflow — undersized return causes negative pressure issues
CFM = Tons × 400 (residential rule of thumb)
Example: 3-ton system → 3 × 400 = 1,200 CFM supply air
Velocity Pressure: VP = (V ÷ 4005)²
V = velocity in FPM, VP = inches w.g.
Typical duct velocities:
Main supply trunk: 700–900 FPM
Branch ducts: 500–700 FPM
Return ducts: 400–600 FPM
Example: 3-ton system → 3 × 400 = 1,200 CFM supply air
Velocity Pressure: VP = (V ÷ 4005)²
V = velocity in FPM, VP = inches w.g.
Typical duct velocities:
Main supply trunk: 700–900 FPM
Branch ducts: 500–700 FPM
Return ducts: 400–600 FPM
ACCA Manual D — Residential Duct Systems. SMACNA HVAC Duct Construction Standards
💰 Job Cost Estimation
Cost estimation for HVAC projects includes equipment, materials, labor, and overhead:
Total Job Cost = Equipment + Materials + Labor + Equipment Rental + Overhead + Profit
Labor = Hours × Hourly Rate
Overhead = typically 10–20% of direct costs
Example:
Equipment: $3,200
Materials (duct, fittings): $800
Labor: 24 hrs × $95/hr = $2,280
Overhead (15%): ($3,200 + $800 + $2,280) × 0.15 = $942
Total = $3,200 + $800 + $2,280 + $942 = $7,222
Labor = Hours × Hourly Rate
Overhead = typically 10–20% of direct costs
Example:
Equipment: $3,200
Materials (duct, fittings): $800
Labor: 24 hrs × $95/hr = $2,280
Overhead (15%): ($3,200 + $800 + $2,280) × 0.15 = $942
Total = $3,200 + $800 + $2,280 + $942 = $7,222
Always calculate equipment and labor separately. The exam often presents costs with mixed rates — read carefully before computing.
SECTION 2 — 29% OF EXAM (LARGEST SECTION)
Fabrication, Installation & Startup
The largest exam section. Covers duct fabrication, equipment installation, electrical/mechanical/refrigeration components, air distribution, and system startup procedures.
🔩 Duct System Fabrication (SMACNA)
All metal ductwork must be fabricated and installed per SMACNA standards. Key requirements:
- Sheet metal gauges: duct size determines minimum gauge — e.g., ducts up to 30" use 26-gauge galvanized steel (SMACNA Table)
- Duct leakage classes: Class 3 = 3 CFM/100 ft² at 1 in.w.g. (typical residential); Class 6 = 6 CFM/100 ft² (less tight)
- California Title 24: ducts in unconditioned space must be sealed to leakage ≤ 15% of fan airflow (verified by duct leakage test)
- Flexible duct: max 5-ft unsupported spans; must be fully extended (never compressed); supports every 4 ft maximum
- Duct insulation: R-8 required for ducts in unconditioned space (California Energy Code)
- Fire dampers: required where ducts penetrate fire-rated assemblies (rated for 1.5 hr or 3 hr)
SMACNA HVAC Duct Construction Standards — Metal and Flexible. 2022 CA Mechanical Code § 601
Flex duct compressed or kinked increases resistance dramatically — a 50% compression can increase resistance by 4× or more. This is a tested exam topic.
🏗 Equipment Installation
Proper equipment installation is the highest-weighted topic. Key requirements by equipment type:
- Gas furnace: must have combustion air supply; min 50 CFM per 10,000 BTU/hr input for confined space
- Furnace clearances: per manufacturer and code — typically 1" side, 6" front for service access
- Condensing furnaces: flue gas is acidic — requires PVC or CPVC vent pipe (not B-vent)
- Split AC outdoor unit: min 12" clearance on service side, min 24" on discharge side; elevate above flood level in flood zones
- Evaporator coil: installed upstream (before) of the furnace heat exchanger in cooling-priority systems; downstream in heating-priority
- Package units: all components in one cabinet — common for rooftop (RTU) commercial applications; eliminates refrigerant line sets
- Condensate drain: primary and secondary required; min ¾" PVC; slope ¼" per foot minimum; secondary drain must be visible to occupant
2022 CA Mechanical Code § 904 — Furnace installation. 2022 CA Energy Code § 150.1
⚡ Electrical & Mechanical Components
HVAC systems require proper electrical connections and mechanical components. Know these:
- Disconnect switch: required within sight of every HVAC unit; must be lockable (NEC 440.14)
- HACR breaker: Heating, Air Conditioning, Refrigeration rated — required for HVAC compressor circuits
- Capacitor: provides starting torque — run capacitors improve efficiency; start capacitors assist startup
- Contactor: heavy-duty relay that switches compressor and condenser fan motor power
- Transformer: steps 240V down to 24V for control circuit (thermostat, control board)
- Control board: sequenced furnace operation — inducer motor → igniter → gas valve → blower
- ECM blower motor: electronically commutated — significantly more efficient than PSC motors; maintains constant CFM
- GFCI protection: required for HVAC equipment in garages, near water, and per local AHJ
2022 CA Electrical Code § 440 — Air conditioning and refrigerating equipment. NEC 440.14 — Disconnecting means.
❄️ Refrigeration Components
The refrigeration cycle is fundamental to HVAC. Know every component and its function:
- Compressor: pumps refrigerant — increases pressure and temperature of refrigerant vapor
- Condenser: rejects heat to outdoor air (or water in water-source systems) — refrigerant condenses from vapor to liquid
- Metering device: reduces refrigerant pressure — TXV (thermostatic expansion valve) or fixed orifice (piston)
- Evaporator: absorbs heat from indoor air — refrigerant evaporates from liquid to vapor, cooling the air
- Reversing valve: found in heat pumps only — reverses refrigerant flow to switch between heating and cooling mode
- Accumulator: prevents liquid refrigerant from entering the compressor (suction side)
- Receiver: stores liquid refrigerant (liquid line side)
- Filter-drier: removes moisture and contaminants from the refrigerant circuit
Water-source heat pump eliminates the air-cooled condenser — heat is rejected to water instead of air. This is the third official CSLB sample question answer.
2022 CA Mechanical Code § 1100 — Refrigeration. EPA Section 608 — Refrigerant handling certification (required for technicians).
🌡 HVAC System Startup Procedure
Startup must be performed in proper sequence to protect equipment:
- Verify power is off; inspect all wiring, connections, and refrigerant lines
- Check refrigerant charge (superheat or subcooling method)
- Inspect and set all controls: thermostat, limits, safety switches
- Open all supply and return registers; verify filter is installed
- Restore power; start system in heating or cooling mode
- Measure supply and return air temperatures — verify ΔT (temperature split)
- Measure amperage on all motors — verify within nameplate rating
- Verify condensate drain flows freely
- Check static pressure across air handler
- Document all readings and provide owner with operating instructions
Cooling: Target ΔT (supply vs return) = 16–22°F
Heating (gas furnace): Target supply air temp = 120–140°F (ΔT ≈ 50–80°F rise)
Heat pump heating: ΔT = 20–30°F (lower than furnace)
Superheat (fixed orifice): Target = 8–12°F above suction saturation temp
Subcooling (TXV): Target = 10–15°F below condensing saturation temp
Heating (gas furnace): Target supply air temp = 120–140°F (ΔT ≈ 50–80°F rise)
Heat pump heating: ΔT = 20–30°F (lower than furnace)
Superheat (fixed orifice): Target = 8–12°F above suction saturation temp
Subcooling (TXV): Target = 10–15°F below condensing saturation temp
SECTION 3 — 24% OF EXAM
Troubleshooting, Repair & Maintenance
Covers HVAC system diagnostic tests, evaluation procedures, maintenance, and repair — grounded in real-world diagnostic skill.
🔍 Diagnostic Tests & Evaluation
Use a systematic approach — measure first, then diagnose. Key diagnostic tools and readings:
- Manifold gauge set: reads high-side (discharge) and low-side (suction) pressures; used with PT chart to find saturation temperatures
- Clamp meter: measures amperage on compressor, fan motors, and blower
- Multimeter: voltage, resistance, and continuity checks — capacitors, contactors, sensors
- Psychrometer: measures DB and WB temperature — used to evaluate system performance
- Anemometer / flow hood: measures air velocity and CFM at registers
- Manometer: measures static pressure in duct system
- Leak detector (electronic): locates refrigerant leaks — more sensitive than soap bubbles for small leaks
- Combustion analyzer: measures flue gas CO, CO₂, O₂, and efficiency for gas systems
Superheat = Suction line temperature – Suction saturation temperature (from PT chart)
Example: Suction line = 55°F, saturation at suction pressure = 45°F → Superheat = 10°F ✓
Subcooling = Condensing saturation temperature (from PT chart) – Liquid line temperature
Example: Saturation at high-side = 110°F, liquid line = 98°F → Subcooling = 12°F ✓
Example: Suction line = 55°F, saturation at suction pressure = 45°F → Superheat = 10°F ✓
Subcooling = Condensing saturation temperature (from PT chart) – Liquid line temperature
Example: Saturation at high-side = 110°F, liquid line = 98°F → Subcooling = 12°F ✓
⚡ Common HVAC Problems & Causes
Cooling Problems
- Low superheat: overcharge, TXV stuck open, or low load
- High superheat: low charge, TXV stuck closed, or restricted filter/duct
- High head pressure: overcharge, dirty condenser, non-condensables (air in system), high ambient temp
- Low head pressure: low charge, compressor failing (low compression)
- Icing on evaporator: low airflow (dirty filter/coil), low refrigerant charge, low ambient
- Warm supply air: low charge, failed compressor, dirty condenser, oversized unit short-cycling
Heating Problems
- No ignition (gas furnace): failed igniter, gas valve closed, no gas pressure, cracked thermocouple
- Furnace locks out: flame sensor dirty (carbon buildup), failed inducer, blocked flue
- High limit trips: dirty filter, blocked registers, duct restriction, failed blower
- Carbon monoxide: cracked heat exchanger — immediately shut down and red-tag
- Heat pump not heating: check reversing valve solenoid, low charge, defrost board issue
- Short cycling: oversized equipment, thermostat location issue, low refrigerant
A cracked heat exchanger is a life-safety emergency — it allows combustion gases including CO to mix with supply air. Always shut down and red-tag the unit immediately. Never just tape or patch a cracked heat exchanger.
🛠 Thermocouple & Ignition Systems
This is directly tested in the official CSLB sample question:
- Thermocouple: a safety device that confirms the existence of a pilot flame — it generates a small millivolt DC signal that holds the gas valve open. If the pilot goes out, the thermocouple cools, voltage drops, and the gas valve closes. This is the CSLB sample answer.
- Thermopile: multiple thermocouples in series — generates higher millivoltage; used in millivolt gas valves
- Hot surface igniter (HSI): silicon carbide or silicon nitride element; heats to ~2000°F to ignite gas; replaces standing pilot in modern furnaces
- Intermittent pilot: electronic spark lights pilot only when heat is called for — more efficient than standing pilot
- Flame sensor (flame rectification): a rod that passes electrical current through the flame — if no flame, current stops and gas valve closes within seconds
2022 CA Mechanical Code § 904.8 — Gas appliance ignition systems.
🔧 Preventive Maintenance Schedule
- Monthly: inspect and replace air filter (1" disposable); check condensate drain for clogs
- Seasonally (pre-cooling): clean condenser coil, check refrigerant charge (superheat/subcooling), inspect electrical connections and capacitor, test contactors, clean evaporator drain pan
- Seasonally (pre-heating): inspect heat exchanger for cracks, check burners and igniter, clean flame sensor, test all safety limits, check flue and combustion air
- Annually: check and tighten all electrical connections, lubricate blower and fan motors (if not sealed), measure static pressure, check duct system for leaks
ASHRAE HVAC Applications Handbook — Maintenance procedures. 2022 CA Mechanical Code § 109 — Required inspections.
SECTION 4 — 22% OF EXAM
Safety
Covers personal protective equipment (PPE), Cal/OSHA job site safety requirements, and handling of hazardous materials including refrigerants.
👷 Personal Protective Equipment (PPE)
- Safety glasses / goggles: required when handling refrigerants, cutting metal ductwork, or working near electrical equipment
- Gloves: insulated gloves for electrical work; chemical-resistant gloves for refrigerant handling
- Hard hat: required on job sites with overhead hazards (rooftop work, construction)
- Steel-toed boots: required for equipment handling and job site work
- Respiratory protection: required when working with refrigerants in confined spaces, brazing, or when CO/combustion gases may be present
- Hearing protection: required at or above 85 dB (8-hr TWA) — Cal/OSHA § 5097
- Knee pads: not a Cal/OSHA requirement but strongly recommended for crawlspace work
Cal/OSHA Title 8 § 3380 — Personal protective equipment requirements.
🏗 Job Site Safety — Cal/OSHA Title 8
- Electrical safety: Lockout/Tagout (LOTO) required before servicing any HVAC unit — Cal/OSHA § 3314. Isolate disconnect, apply lock, verify zero voltage.
- Ladder safety: 4:1 ratio (1 ft out for every 4 ft up); extend 3 ft above landing; 3-point contact rule; no overloading rated capacity
- Rooftop safety: fall protection required at 6 ft above lower level (construction) — guardrails, safety nets, or personal fall arrest system
- Confined spaces: attics, crawlspaces, and mechanical rooms may be confined spaces — assess atmosphere (O₂, CO, flammable gas) before entry
- Brazing/soldering: fire watch required; keep fire extinguisher within reach; use shields near combustibles
- Nitrogen: always use a regulator when pressurizing systems with nitrogen — never use oxygen (fire/explosion risk)
- Right-to-Know / SDS: Safety Data Sheets required on site for all chemicals (refrigerants, flux, coil cleaner)
NEVER use oxygen to pressurize or leak-test refrigeration systems. Oxygen in contact with refrigerant oil can cause a violent explosion. Use dry nitrogen only.
Cal/OSHA Title 8 § 3314 — Lockout/Tagout. Cal/OSHA § 1670 — Fall protection.
☢️ Hazardous Materials — Refrigerant Handling
Refrigerant handling is heavily regulated by EPA Section 608 and California ARB:
- EPA Section 608 certification: required to purchase and handle regulated refrigerants. Types: I (small appliances), II (high-pressure), III (low-pressure), Universal
- Venting prohibition: intentional venting of CFC, HCFC, or HFC refrigerants is illegal — federal Clean Air Act violation
- Recovery required: must recover refrigerant before opening any system — use EPA-certified recovery equipment
- Common refrigerants:
R-22 (HCFC) — phased out for new equipment; still in older systems
R-410A (HFC) — current residential standard (higher pressure than R-22)
R-32, R-454B — next-generation lower GWP refrigerants (A2L mildly flammable)
R-134a — automotive and commercial refrigeration - Refrigerant cylinders: never fill beyond 80% capacity; store upright; keep from heat sources; yellow cylinder = recovery refrigerant only
- California ARB: additional refrigerant regulations for high-GWP refrigerants — reporting requirements for large commercial systems
R-410A operates at pressures up to 600 psi (compared to ~250 psi for R-22). Always use R-410A-rated hoses, gauges, and recovery equipment. R-22 equipment is not rated for R-410A pressures.
EPA Section 608 — Refrigerant recovery/recycle/reclaim regulations. California ARB — HFC regulations.
🔥 Combustion Safety
- Carbon monoxide (CO): colorless, odorless, deadly — produced by incomplete combustion. Detector required per California code in all homes with gas appliances
- CO threshold: OSHA PEL = 50 ppm (8-hr TWA); immediately dangerous at 1,200 ppm
- Natural gas: flammable range 5–15% concentration in air (LEL 5%, UEL 15%); lighter than air; rises
- Propane (LP): flammable range 2.1–9.5%; heavier than air — settles in low areas; evacuate and ventilate before ignition
- Gas leak response: evacuate, do NOT operate switches or phones inside, call gas company from outside
- Combustion air: gas appliances require adequate combustion air supply — minimum per CMC based on BTU input and space volume
2022 CA Mechanical Code § 701 — Combustion air requirements. Cal/OSHA § 5155 — Airborne contaminants (CO limits).
🧠 INTERACTIVE PRACTICE EXAM
Practice Quiz
Real-style questions matching CSLB C-20 exam format — 4 choices, one best answer, full code-cited explanations. Includes all 3 official CSLB sample questions.
Section: All
Question: 1 / 30
Score: 0 correct
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🃏 FLASHCARD DRILL
Flashcards
Click the card to flip and reveal the answer. Drill these until automatic — formulas, code numbers, equipment rules, and refrigerant facts.
QUESTION — Click to flip
ANSWER
1 / 32
📋 All Cards — Quick Reference
Full list of all flashcard terms and answers:
🔢 MATH, FORMULAS & CALCULATORS
Math & Formulas
Interactive calculators for every math formula that appears on the C-20 exam. All formulas shown with step-by-step work.
⚡ EER / COP Calculator
Formula: EER = BTU/hr ÷ Watts — The official CSLB sample question tests this directly.
Enter values to calculate EER and COP
🌡 Heat Load Calculator (Conduction)
Formula: Q = U × A × ΔT — Used for Manual J wall, roof, and window load calculations.
Enter values to calculate heat load
💨 CFM & System Sizing Calculator
Rule: ~400 CFM per ton of cooling (residential)
Enter system size to calculate required airflow
💰 HVAC Job Cost Estimator
Total = Equipment + Materials + Labor + Overhead
Enter values to calculate total job cost
📊 Master Formula Sheet
EER = BTU/hr ÷ Watts
COP = EER ÷ 3.412
SEER = Seasonal avg EER (annualized)
CA Min (2023+): 15 SEER2 residential split
COP = EER ÷ 3.412
SEER = Seasonal avg EER (annualized)
CA Min (2023+): 15 SEER2 residential split
Heat Load: Q = U × A × ΔT
U = 1 ÷ R-total (R-value = 1/U)
Infiltration: Q = 1.1 × CFM × ΔT (sensible)
Latent: Q = 0.68 × CFM × ΔW (gr/lb)
U = 1 ÷ R-total (R-value = 1/U)
Infiltration: Q = 1.1 × CFM × ΔT (sensible)
Latent: Q = 0.68 × CFM × ΔW (gr/lb)
CFM = Tons × 400 (cooling, residential)
Velocity: V (FPM) = CFM ÷ Area (ft²)
Area of round duct: A = π × r²
Area of rect duct: A = W × H
Velocity: V (FPM) = CFM ÷ Area (ft²)
Area of round duct: A = π × r²
Area of rect duct: A = W × H
Superheat = Suction line temp – Sat temp (low side)
Subcooling = Sat temp (high side) – Liquid line temp
Target superheat (fixed orifice): 8–12°F
Target subcooling (TXV): 10–15°F
Subcooling = Sat temp (high side) – Liquid line temp
Target superheat (fixed orifice): 8–12°F
Target subcooling (TXV): 10–15°F
ΔT Cooling: 16–22°F (supply vs return)
ΔT Gas Furnace: 50–80°F rise
ΔT Heat Pump Heating: 20–30°F
Combustion air: 50 CFM per 10,000 BTU/hr input
ΔT Gas Furnace: 50–80°F rise
ΔT Heat Pump Heating: 20–30°F
Combustion air: 50 CFM per 10,000 BTU/hr input
Job Cost:
Labor = Hours × Rate
Overhead = (Equip + Mat + Labor) × %
Total = Equip + Mat + Labor + Overhead + Profit
Labor = Hours × Rate
Overhead = (Equip + Mat + Labor) × %
Total = Equip + Mat + Labor + Overhead + Profit
📚 CODE & TECHNICAL REFERENCE TABLES
Code Reference
Key code sections, efficiency standards, refrigerant properties, and HVAC specs. Memorize these — no books allowed in the exam.
| Code / Standard | Topic | Exam Relevance |
|---|---|---|
| 2022 CA Mechanical Code § 301 | HVAC equipment approval & listing | High |
| 2022 CA Mechanical Code § 601 | Duct construction standards | Very High |
| 2022 CA Mechanical Code § 701 | Combustion air requirements | High |
| 2022 CA Mechanical Code § 904 | Gas furnace installation & clearances | Very High |
| 2022 CA Mechanical Code § 1100 | Refrigeration systems | High |
| 2022 CA Energy Code § 150.1 | HVAC equipment efficiency minimums | Very High |
| 2022 CA Energy Code § 150.0(m) | Duct insulation (R-8 unconditioned space) | High |
| 2022 CA Electrical Code § 440 | AC & refrigeration electrical | High |
| ACCA Manual J | Residential load calculation | Very High |
| ACCA Manual D | Residential duct system design | High |
| ACCA Manual S | Equipment selection | Medium |
| SMACNA Duct Construction Stds | Metal duct gauge, leakage, joints | High |
| EPA Section 608 | Refrigerant handling certification | Very High |
| Cal/OSHA Title 8 § 3314 | Lockout/Tagout (LOTO) | High |
| Cal/OSHA Title 8 § 5157 | Confined spaces | Medium |
| Refrigerant | Type | Application | Pressure (suction @ 45°F) | Notes |
|---|---|---|---|---|
| R-22 | HCFC | Legacy residential | ~68 psi | Phased out — no new production |
| R-410A | HFC blend | Current residential | ~118 psi | High pressure — 410A tools required |
| R-32 | HFC | Next-gen residential | ~119 psi | A2L — mildly flammable |
| R-454B | HFC blend | R-410A replacement | ~105 psi | A2L — lower GWP than R-410A |
| R-134a | HFC | Auto / commercial | ~27 psi | Common in cars, med-temp commercial |
| R-404A | HFC blend | Low-temp commercial | ~50 psi @ 0°F | Being phased down (high GWP) |
| Component | Function | Location in Cycle | Failure Symptom |
|---|---|---|---|
| Compressor | Pumps refrigerant; increases pressure | Between accumulator & condenser | Low head pressure, high suction pressure, no cooling |
| Condenser | Rejects heat; condenses vapor to liquid | High side — outdoors (air-cooled) | High head pressure if dirty/blocked |
| TXV / Metering Device | Reduces pressure; controls refrigerant flow | Between liquid line & evaporator | Stuck open: low superheat. Stuck closed: high superheat |
| Evaporator | Absorbs heat; evaporates liquid to vapor | Low side — indoor air handler | Icing if dirty/low airflow or low charge |
| Reversing Valve | Switches heating/cooling mode | Heat pumps only — near compressor | Stuck: won't switch modes |
| Accumulator | Prevents liquid refrigerant to compressor | Suction line before compressor | Liquid slugging if absent or failed |
| Filter-Drier | Removes moisture and debris | Liquid line | Restriction: low suction, low head if plugged |
| Capacitor | Starting/running torque for motors | Compressor, condenser fan, blower | Motor hums but won't start; or runs hot |
| Measurement | Tool | Normal Range | Action if Out of Range |
|---|---|---|---|
| Superheat (fixed orifice) | Manifold gauges + thermometer | 8–12°F | Low: overcharge or TXV open. High: undercharge or restriction |
| Subcooling (TXV) | Manifold gauges + thermometer | 10–15°F | Low: undercharge. High: overcharge or restriction |
| Supply/Return ΔT (cooling) | Digital thermometer | 16–22°F | Low: low charge or low airflow. High: very low airflow |
| Static pressure (total) | Manometer | 0.5 in.w.g. max (typical) | High: dirty filter, blocked duct, undersized duct |
| Compressor amperage | Clamp meter | Per nameplate RLA/LRA | High: over-voltage, bad capacitor, low refrigerant |
📅 10-WEEK STUDY PLAN
Your Road to Passing C-20
Structured around the four exam section weights. Follow this plan for 2–3 months and you'll be fully prepared on exam day.
⏰ Weekly Time Commitment
Minimum: 8–10 hrs/week (1.5 hrs weekdays + 2 hrs each weekend day)
Optimal: 12–15 hrs/week (2 hrs weekdays + 3 hrs each weekend day)
Goal: Score 80%+ on practice quizzes before exam day (passing is 70%)
Section 2 (Fabrication & Install, 29%) is the LARGEST — give it the most time.
Optimal: 12–15 hrs/week (2 hrs weekdays + 3 hrs each weekend day)
Goal: Score 80%+ on practice quizzes before exam day (passing is 70%)
Section 2 (Fabrication & Install, 29%) is the LARGEST — give it the most time.
WEEKS 1–2
📐 Section 1: Planning & Estimating + Exam Orientation
Goals: Master load calculation concepts (Manual J), psychrometrics, EER/COP formulas, duct design principles (Manual D), and cost estimation.
Daily tasks: Study Planning & Estimating notes above. Do the EER and heat load calculators until you get them instantly. Memorize: EER = BTU/hr ÷ Watts. Practice the CSLB sample EER question (24,000 ÷ 2,400 = 10.0). Understand sensible vs. latent heat.
Quiz target: Score 70%+ on Planning section before moving on.
Flashcards: EER, COP, SEER2 minimum, CFM per ton, Manual J/D/S, sensible/latent definitions.
Daily tasks: Study Planning & Estimating notes above. Do the EER and heat load calculators until you get them instantly. Memorize: EER = BTU/hr ÷ Watts. Practice the CSLB sample EER question (24,000 ÷ 2,400 = 10.0). Understand sensible vs. latent heat.
Quiz target: Score 70%+ on Planning section before moving on.
Flashcards: EER, COP, SEER2 minimum, CFM per ton, Manual J/D/S, sensible/latent definitions.
WEEKS 3–5
🔧 Section 2: Fabrication, Installation & Startup (largest section — 3 weeks)
Goals: Master every component of the refrigeration cycle. Know duct construction standards (SMACNA), R-8 insulation for unconditioned ducts, California Title 24 duct leakage rules. Know electrical requirements (disconnect, HACR breaker, capacitor, contactor). Master startup procedures and target ΔT values.
Week 3: Refrigeration cycle — every component, function, and failure symptom. Study the refrigerant comparison table.
Week 4: Duct fabrication, insulation, leakage testing, flexible duct rules. Equipment clearances and installation requirements.
Week 5: Electrical components, startup procedure, target temperatures (superheat/subcooling/ΔT).
Quiz target: Score 75%+ on Fabrication & Install section.
Flashcards: Refrigerant pressures, component functions, R-410A vs R-22 pressures, capacitor roles, ΔT targets.
Week 3: Refrigeration cycle — every component, function, and failure symptom. Study the refrigerant comparison table.
Week 4: Duct fabrication, insulation, leakage testing, flexible duct rules. Equipment clearances and installation requirements.
Week 5: Electrical components, startup procedure, target temperatures (superheat/subcooling/ΔT).
Quiz target: Score 75%+ on Fabrication & Install section.
Flashcards: Refrigerant pressures, component functions, R-410A vs R-22 pressures, capacitor roles, ΔT targets.
WEEKS 6–7
🔬 Section 3: Troubleshooting, Repair & Maintenance
Goals: Know all diagnostic tools and their use. Be able to read superheat and subcooling values and diagnose the problem. Know thermocouple vs. thermopile vs. flame sensor vs. hot surface igniter. Know when to shut down a system (cracked heat exchanger = immediate red-tag).
Daily tasks: Study all troubleshooting cause-and-effect scenarios. Practice: given a symptom, what is the most likely cause? Drill the thermocouple CSLB sample question. Study maintenance schedules.
Quiz target: Score 75%+ on Troubleshooting section. These questions are very scenario-based — think like a tech, not a textbook.
Daily tasks: Study all troubleshooting cause-and-effect scenarios. Practice: given a symptom, what is the most likely cause? Drill the thermocouple CSLB sample question. Study maintenance schedules.
Quiz target: Score 75%+ on Troubleshooting section. These questions are very scenario-based — think like a tech, not a textbook.
WEEK 8
🦺 Section 4: Safety
Goals: Master EPA Section 608 refrigerant rules (no venting, recovery required, cylinder rules). Know LOTO procedure. Know nitrogen vs. oxygen for leak testing. Know CO limits and gas flammable ranges. Know Cal/OSHA PPE and fall protection heights.
Daily tasks: Study all Safety notes above. Memorize the nitrogen rule (NEVER use oxygen). Memorize natural gas vs. propane properties (LP is heavier than air). Know the CO PEL (50 ppm). Practice safety scenario questions.
Quiz target: Score 80%+ on Safety section — it's the most rule-based and should be one of your highest scoring sections with good preparation.
Daily tasks: Study all Safety notes above. Memorize the nitrogen rule (NEVER use oxygen). Memorize natural gas vs. propane properties (LP is heavier than air). Know the CO PEL (50 ppm). Practice safety scenario questions.
Quiz target: Score 80%+ on Safety section — it's the most rule-based and should be one of your highest scoring sections with good preparation.
WEEKS 9–10
🧠 Full Practice Exams + Weak Area Drilling
Goals: Simulate real exam conditions. Build exam-day confidence.
Daily tasks: One full 25-question mixed quiz per day — timed, no notes. Review every wrong answer, understand WHY. Spend extra time on any section scoring below 70%. Run all flashcards daily. Re-do the math calculators from memory.
Target: Score 80%+ consistently before exam day. If you're hitting 75–80%, you're on track to pass.
Daily tasks: One full 25-question mixed quiz per day — timed, no notes. Review every wrong answer, understand WHY. Spend extra time on any section scoring below 70%. Run all flashcards daily. Re-do the math calculators from memory.
Target: Score 80%+ consistently before exam day. If you're hitting 75–80%, you're on track to pass.
EXAM WEEK
✅ Final Review & Exam Day
Mon–Wed: Light review — flashcards once, formula sheet, one short quiz per day. No heavy cramming.
Thu: Rest. Good sleep is worth more than 2 hours of cramming.
Exam Day: Arrive early. Bring photo ID. Calculator is provided. Read every question fully — CSLB uses distractors that look right. Trust your prep. For hard questions: eliminate 2 options, then pick the more conservative/code-compliant answer.
Thu: Rest. Good sleep is worth more than 2 hours of cramming.
Exam Day: Arrive early. Bring photo ID. Calculator is provided. Read every question fully — CSLB uses distractors that look right. Trust your prep. For hard questions: eliminate 2 options, then pick the more conservative/code-compliant answer.
All 3 CSLB sample questions are in this course. If you can explain WHY each answer is correct (not just memorize the answer), you understand the exam's style. Apply that same thinking to every question.
📌 Full C-20 License Requirements Checklist
You Must Pass TWO Exams
1. C-20 Trade Exam — this course covers this
2. Law & Business Exam — covers CSLB regulations, contracting laws, lien rights, insurance, workers' comp, and business practices
Study the Law & Business exam separately — it's a separate exam with separate prep materials.
Requirements Before Applying
- ☐ 4 years HVAC experience (in last 10 years)
- ☐ Application Form 13A-1 to CSLB
- ☐ $450 application fee
- ☐ $15,000 contractor bond
- ☐ Workers' comp (if you have employees)
- ☐ Pass C-20 Trade Exam (this course)
- ☐ Pass Law & Business Exam
- ☐ EPA Section 608 certification (for refrigerant work)
- ☐ Receive C-20 license from CSLB