Hoja de Referencia del Examen · Referencia Rápida
Oklahoma HVACR Contractor, Limited
Oklahoma · PSI Services Contractor
Verificado, no estimado. Cada cifra a continuación proviene de la estructura oficial del examen que mantenemos: número de preguntas, puntaje de aprobación y ponderación de temas. Las preguntas de práctica están fundamentadas en la ley fuente con citas de estatutos. Omitimos cualquier cifra que no podamos verificar en lugar de adivinarla.
Total de preguntas
80
Puntaje de aprobación
70%
Tiempo del examen
210 min
Administrado por
PSI Services Contractor
Formato
Se permiten materiales de referencia
Porción Estatal de Oklahoma 80 preguntas
Conocimientos Eléctricos y Controles
15 Q · 19%
Circuit diagrams: pictorial and ladder diagramsOhm's law and Watt's law calculationsSingle-phase and three-phase AC motors: types, starting methods, and capacitorsMotor starting relays: current, potential, solid-state, and PTC relaysPressure and temperature motor controls: cut-in, cut-out, range, and differential adjustmentMotor protection devices: fuses, circuit breakers, and bimetal/thermistor overload protectionElectrical test equipment: voltmeters, ammeters, ohmmeters, and multimetersTroubleshooting hermetic compressor motors: winding resistance, shorts, and groundsControl transformers and 24-volt control circuits
Gas Natural
12 Q · 15%
Gas piping materials, fittings, and allowable pipe types (steel, copper, CSST, PE)Gas piping sizing methods and capacity tables (longest length, branch length, hybrid pressure)Gas piping pressure requirements, testing, and leak checksCombustion air requirements for gas-fired appliances (indoor, outdoor, and combination methods)Venting system types and selection by appliance category (Type B, single-wall, direct-vent, Categories I-IV)Chimney and vent sizing for Category I appliances (draft hood and fan-assisted)Vent connector installation requirements, clearances, and termination locationsGas furnace combustion principles, ignition systems, and safety controls
Sistemas de Distribución de Aire
15 Q · 19%
Duct types, construction materials, and system configurations (radial, extended plenum, reducing trunk, perimeter loop, SDHV)Duct sizing procedures and ACCA Manual D requirementsRegisters, diffusers, and grilles — selection, placement, and airflow characteristicsDampers — types (butterfly, multiple-blade, split, fire, smoke), installation, and automatic controlsDuct insulation, sealing methods, and vapor retarder requirements (IMC Chapter 6)Airflow measurement tools and techniques (flow hoods, manometers, pitot tubes, blower door testing, duct blaster testing)Ventilation requirements — air changes per hour, fresh air intake, positive/negative pressure, and IMC Chapter 4 outdoor airflow ratesDuct system service — balancing, noise troubleshooting, cleaning procedures, and air filter maintenance
Sistemas de Refrigeración y Aire Acondicionado
20 Q · 25%
Compression refrigeration cycle components and operationRefrigerant classification, properties, and environmental regulations (EPA/Clean Air Act)Refrigerant handling equipment: cylinders, gauge manifolds, service valves, and leak detectionRefrigerant recovery, recycling, reclaiming, evacuation, and charging proceduresMetering devices: capillary tubes, TXVs, AXVs, EEVs, and fixed-orifice typesCompressor types, configurations, and safety protection componentsHeat exchangers: evaporator and condenser types, defrost methods, and head pressure controlRefrigerant flow components: filter-driers, sight glasses, check valves, solenoid valves, and pressure-regulating valves
Sistemas de Calefacción
15 Q · 19%
Gas-fired heating systems: burners, ignition systems, and combustion controlsOil-fired heating systems: burner components, fuel delivery, and combustion efficiency testingHydronic heating system components: boilers, circulating pumps, expansion tanks, and terminal unitsHeat pump operation: reversing valves, metering devices, and heating/cooling modesElectric resistance heating systems: furnaces, duct heaters, baseboard units, and radiant heatHydronic system designs: series loop, one-pipe, two-pipe, zoned, and radiant systemsBoiler safety controls and code requirements: pressure relief valves, low-water cutoffs, and IMC Chapter 10 provisionsForced-air furnace types and efficiency ratings: upflow, downflow, condensing vs. noncondensing, and AFUE
Seguridad
3 Q · 4%
Electrical hazards and lockout/tagout (LOTO) proceduresFire hazards and fire extinguisher use (P.A.S.S.)Refrigerant cylinder safety and pressure hazardsPersonal protective equipment (PPE) selection and useHazard Communication Standard (HCS), GHS labeling, and safety data sheets (SDS)Breathing hazards and respiratory protectionLadder, scaffolding, and fall protection safetyConfined space safety and safe work practices
Distinciones Clave
Pictorial Wiring DiagramvsLadder Diagram
Pictorial diagrams show approximate physical location of devices and may include wire colors, while ladder diagrams show order of component operation using horizontal rungs between two vertical power lines.
Chapter 16, Section 16.1.1Motor StartervsContactor
A motor starter includes built-in overload protection, whereas a contactor does not.
Modern Refrigeration and Air Conditioning, Chapter 16, Section 16.3.5 — Contactors and Motor StartersBuilding-Related Illness (BRI)vsSick Building Syndrome (SBS)
BRI is a specifically diagnosable illness whose symptoms do not disappear when the occupant leaves the building, while SBS has no identifiable illness or specific cause and symptoms resolve when occupants leave.
Modern Refrigeration and Air Conditioning, Page 730Hard LockoutvsSoft Lockout
A hard lockout shuts down the furnace indefinitely and requires a power interruption or service call to reset, while a soft lockout automatically retries ignition after a waiting period.
Modern Refrigeration and Air Conditioning, Page 1129Fusible Link (electric furnace safety)vsBimetal Disc Safety Cutoff
A fusible link cannot be reset once it opens and must be replaced entirely, whereas a bimetal disc can be reset after it trips.
Modern Refrigeration and Air Conditioning, Pages 1208-1209Weight-Operated Current RelayvsRotary Solenoid Current Relay
A weight-operated current relay must be mounted in a level position, while a rotary solenoid current relay can be mounted in any position.
Modern Refrigeration and Air Conditioning, Chapter 16, Section 16.3.5 — Current RelaysK-Value (Thermal Conductivity)vsC-Value (Thermal Conductance)
K-value measures heat transfer through a material standardized to one inch thick, while C-value describes thermal conductance based on the material's actual measured thickness.
Modern Refrigeration and Air Conditioning, Page 986ACR Tubing SizingvsCopper Water Tubing Sizing
ACR tubing is sized by its actual outside diameter, while copper water tubing nominal size equals the outside diameter minus 1/8 inch.
Modern Refrigeration And Air Conditioning, Chapter 8, Section 8.1.1PTC Thermistor (cold state)vsPTC Thermistor (heated state)
When cool, a PTC thermistor has low resistance (3–12 Ω) allowing current to flow through it; once heated to its set point, resistance rises dramatically (10–20 kΩ), forcing current through the run capacitor instead.
Chapter 16, Section 16.3.5 — Positive Temperature Coefficient RelaysSolid-State Relay (SSR)vsElectromagnetic Relay
An SSR switches circuits using electronic components (transistors, SCRs, triacs) with no physical mechanical movement, while an electromagnetic relay uses mechanical contacts that physically open and close.
Chapter 16, Section 16.3.5 — Solid-State RelaysSeries CircuitvsParallel Circuit
In a series circuit, current has only one path so opening any device breaks the entire circuit; in a parallel circuit, devices share voltage across multiple paths so one device opening does not interrupt others.
Chapter 12, Section 12.4.2Hot-Surface Ignition (HSI) SystemvsStanding-Pilot System
HSI systems use a glow coil for ignition and a separate flame rod for flame sensing via flame rectification, while standing-pilot systems use a thermocouple to sense a continuously burning pilot flame.
Modern Refrigeration and Air Conditioning, Pages 1126-1128 (Sections 41.5.4 and 41.6.1)Términos Clave
Duct Sizing — Single Dwelling Unit (ACCA Manual D) International Mechanical Code 2021, Section 603.2
Per IMC Section 603.2, ducts in a single dwelling unit must be sized in accordance with ACCA Manual D, the appliance manufacturer's instructions, or other approved methods.
Duct Leakage Test Pressure Modern Refrigeration and Air Conditioning, Page 792
Per Modern Refrigeration and Air Conditioning, ductwork is pressurized to +25 Pa with respect to the conditioned space during a duct leakage test, and the airflow required to maintain that pressure is expressed as cfm25.
Maximum Duct Leakage (pre-air-handler installation) Modern Refrigeration and Air Conditioning, Page 793
Per the IECC as cited in Modern Refrigeration and Air Conditioning, if ductwork is tested before the air handler is installed, maximum allowable leakage is 3 cfm per 100 ft² of conditioned space.
High-Pressure Motor Control Cutout Setting Chapter 16, Section 16.3.4 — High-Pressure Motor Controls
Per Chapter 16, Section 16.3.4, a high-pressure motor control safety device is typically set to cut out at 20% above normal head pressure.
Centrifugal Switch Disconnect Speed (Split-Phase Motor) Chapter 15, Section 15.2.1 — Split-Phase Motors
Per Chapter 15, Section 15.2.1, a split-phase motor's centrifugal switch disconnects the start winding at approximately 75% of the motor's rated running speed.
Low-Voltage Control Circuit Voltage Chapter 17, Section 17.1.1
Per Chapter 17, Section 17.1.1, low-voltage control circuits in HVACR systems typically operate at 24 V, supplied by a transformer that steps down line voltage.
Differential (pressure/temperature control) Chapter 16, Section 16.2.2
Per Chapter 16, Section 16.2.2, the differential is the numerical difference between the cut-out and cut-in values of a control, representing the operating swing of the system.
Velocity Pressure Modern Refrigeration and Air Conditioning, Page 710
The difference between total air pressure and static air pressure, measured by a pitot tube, which is used to determine airflow velocity.
Subcooling Modern Refrigeration and Air Conditioning, Page 68
Subcooling is the difference between a liquid refrigerant's condensing (boiling) point at operating pressure and its actual measured temperature, calculated as condensing temperature minus liquid temperature.
Zeotropic Refrigerant Blend (400 Series) — Fractionation Modern Refrigeration and Air Conditioning, Page 259
Zeotropic blends such as R-410A must be charged as a liquid because vapor charging causes fractionation, where component refrigerants with different boiling points separate and create an improper mixture in the system.
cfm50 (Blower Door Test) Modern Refrigeration and Air Conditioning, Page 791
cfm50 is the airflow through a blower door fan when indoor pressure is held at −50 Pa with respect to outdoors, used to calculate air changes per hour (ACH50).
Potential Relay Pickup Voltage Chapter 16, Section 16.3.5 — Potential Relays
A potential relay energizes and opens its normally closed start-capacitor contacts when counter electromotive force (cemf) in the start winding reaches the relay's pickup voltage, typically at about 75% of rated motor speed.
Draft (combustion) Modern Refrigeration and Air Conditioning, Page 1155
Draft is the movement of flue gas measured in inches of water column (in. WC) using a draft gauge, indicating how quickly combustion gases pass through the heat exchanger.
Acceptable CO₂ Content — Natural Gas Furnace Flue Gas Modern Refrigeration and Air Conditioning, Page 1120
With excess air accounted for, acceptable carbon dioxide content in natural gas furnace flue gas should be approximately 7.6%, compared to the theoretical maximum of 11.9%.
Maximum Duct Air Velocity (noise threshold) Modern Refrigeration and Air Conditioning, Page 773
Per Modern Refrigeration and Air Conditioning, duct air velocities above 700 fpm can cause excessive noise in the duct system.
Fórmulas que Debes Saber
Ohm's Law — Resistance
R = E ÷ I (Resistance in ohms = Voltage in volts ÷ Current in amperes)Ohm's Law — Current
I = E ÷ R (Current in amperes = Voltage in volts ÷ Resistance in ohms)Watt's Law — Power (single-phase)
P = I × E (Power in watts = Current in amperes × Voltage in volts)Subcooling
Subcooling = Condensing temperature (at operating pressure) − Actual liquid temperatureSystem Differential (pressure or temperature control)
Differential = Cut-out value − Cut-in valueTotal Air Pressure
Total pressure = Static pressure + Velocity pressureSeries Circuit — Total Voltage Drop
VD₁ + VD₂ + VD₃ + … = V_Total (applied voltage)