Oklahoma - HVACR JOURNEYMAN LIMITED

Key Concepts

Circuit Diagrams - Pictorial diagrams show components as they physically appear; used for installation reference. - Ladder diagrams show circuits as horizontal "rungs" between two vertical power rails; used for troubleshooting logic. Control circuits appear on the left, loads on the right rung.

Ohm's Law & Watt's Law - V = I × R | I = V/R | R = V/I - P = V × I | P = I² × R | P = V²/R - Know all transpositions — exam questions give two values and ask you to solve for the third.

Single-Phase AC Motors - Split-phase (induction start): start winding has higher resistance, lower inductance than run winding; disconnected at ~75% of full speed. - Capacitor-start: electrolytic capacitor in series with start winding for high starting torque; capacitor disconnected at speed. - Capacitor-start/capacitor-run (CSR): two capacitors — large electrolytic for starting, smaller AC-rated capacitor permanently in run circuit for efficiency. - Permanent split capacitor (PSC): single run capacitor always in circuit; low starting torque, common on fan motors and small compressors.

Three-Phase Motors - No capacitors or start windings needed — phase displacement provides rotating magnetic field automatically. - Terminals labeled T1, T2, T3; reversing any two leads reverses rotation.

Study Brief (9 Questions, 15% of Exam)

Key Concepts

Gas Piping Materials & Fittings

• Steel pipe (black or galvanized): Most common for gas piping; threaded connections.
• Copper tubing: Allowed for natural gas only where gas is not corrosive; must use flare or solder fittings rated for gas.
• CSST (Corrugated Stainless Steel Tubing): Listed and labeled; must be bonded per code; not allowed in some corrosive environments.
• PE (Polyethylene): Underground exterior use only; never inside buildings.
• Prohibited materials: Cast iron, lead, tin-lined, zinc-lined pipe for gas service.

Gas Piping Pressure & Testing

• Low-pressure systems: 0.5 psig (14" W.C.) or less — standard residential supply.
• Medium pressure: 0.5–2 psig.
• Test pressure (IFGC): Systems operating at ≤ 0.5 psig must be tested at minimum 3 psig for at least 10 minutes with no pressure drop.
• Leak check: After testing, check joints with approved gas-detection solution or approved electronic detector — never an open flame.
• Plastic pipe must never be pressure tested with air inside a building (use inert gas or water).

Key Concepts

Duct System Configurations

• Radial: Individual ducts run from a central plenum to each register — common in slab-on-grade construction
• Extended plenum: Main trunk runs full-size with branches tapping off; simple to install
• Reducing trunk: Trunk steps down in size as flow decreases — more efficient static pressure management
• Perimeter loop: Continuous loop around building perimeter; best for cold climates with slab floors
• SDHV (Small Duct High Velocity): 1.5–2" diameter ducts at 600–900 FPM; uses high-velocity mixing for comfort; requires special equipment

Duct Construction & Insulation (IMC Chapter 6)

• Duct insulation R-values and vapor retarders are required to prevent condensation on cold duct surfaces
• Vapor retarder must face the warm, moist side (exterior of insulation in cooling climates)
• Duct sealing: All transverse joints, longitudinal seams, and connections must be sealed with mastic, mastic-plus-mesh, or UL 181-listed tape — standard cloth duct tape is NOT code-compliant for sealing

ACCA Manual D — Duct Sizing

• Manual D is the industry-standard procedure for residential duct design
• Sizing is based on available static pressure and required airflow (CFM) to each room (from Manual J load calculation)
• Total Effective Length (TEL) = straight duct length + equivalent lengths of all fittings
• Friction rate = Available Static Pressure ÷ TEL × 100 (expressed as inches W.C. per 100 feet)

Oklahoma HVACR Journeyman Limited – Study Brief

Key Concepts

Compression Refrigeration Cycle The basic cycle moves heat via four components: compressor (raises refrigerant pressure/temperature), condenser (rejects heat, refrigerant liquefies), metering device (drops pressure), and evaporator (absorbs heat, refrigerant boils). High-side = compressor discharge through condenser to metering device inlet. Low-side = metering device outlet through evaporator to compressor suction.

Refrigerant Classification (ASHRAE 34) - First letter = flammability: A = lower flammability/nonflammable, B = higher toxicity - Number = flammability level (1 = no flame, 2 = lower flammability, 3 = higher flammability) - Common examples: R-410A = A1, R-22 = A1, R-32 = A2L, Ammonia (R-717) = B2L, R-290 (propane) = A3 - Per IMC 1103.1, refrigerants are classified per ASHRAE 34 as listed in Table 1103.1 - IMC 1101.1.2: Ammonia systems follow IIAR 2–5, not IMC Chapter 11

EPA/Clean Air Act – Section 608 - Technicians must be EPA 608 certified to purchase or handle refrigerants - Venting of refrigerants is illegal; recovery is required before opening any system - De minimis releases (accidental) may be exempt if good faith efforts were made - Refrigerant purity for reuse: recovered refrigerant may only be reused in the same owner's equipment or same system (IMC 1102.2.2.2); reuse in a different owner's equipment requires reclamation to AHRI 700 standards (IMC 1102.2.2.3) - Refrigerant blends with different ASHRAE 34 designations **cannot be…

Key Concepts

Gas-Fired Heating Systems

• Ignition systems: Standing pilot, intermittent pilot (IPI), and hot surface ignition (HSI). HSI elements are typically silicon carbide or silicon nitride; normal resistance range is 40–90 ohms (cold).
• Combustion controls: Flame rectification sensors confirm burner operation; a faulty sensor causes lockout within 7–10 seconds. Draft inducers on 80%+ furnaces create negative pressure before ignition — proves via pressure switch.
• Primary/secondary air: Primary air mixes with gas before combustion; secondary air surrounds the flame to complete combustion.

Oil-Fired Heating Systems

• Burner components: Fuel unit (pump), nozzle, electrodes, ignition transformer, air tube, and blast tube. Nozzle size is rated in GPH and spray angle.
• Fuel delivery: Fuel unit pressure typically set at 100–150 PSI for pressure-atomizing burners.
• Combustion efficiency testing: Use a combustion analyzer — measure CO₂ % (ideal: 10–12% for oil), stack temperature, and smoke spot number (Bacharach scale, target: 0–1). Calculate efficiency = 100% − stack losses.

Hydronic Heating Systems

• Boilers: Cast iron sectional, steel fire-tube, or copper tube. Hot water boilers operate at <250°F and <160 PSI (per ASME classification).
• Circulating pumps: Centrifugal type; sized for GPM and head pressure. Install with pump impeller shaft horizontal.
• Expansion tanks: Closed (bladder/diaphragm) tanks are pre-charged with air (typically 12 PSI); sized to accommodate system water expansion. Open tanks are gravity-fed and installed at the highest…

Weight: 5% of exam | ~3 questions | Source: Modern Refrigeration and Air Conditioning, Chapter 2 (pp. 22–41)

Key Concepts

Lockout/Tagout (LOTO)

• Lockout (LO): Physically locking an electrical switch/mechanism in the open (off) position so service can be performed safely.
• Tagout (TO): Placing an identifying tag on a switch/mechanism to warn others not to change its position.
• LOTO combined: Lock the panel open AND tag it — technician holds the key.
• OSHA standard: Use lockout devices whenever equipment can be locked out. Tagout alone is only acceptable if it provides equivalent protection to lockout.
• Never assume someone else shut off the power — personally verify the circuit is de-energized.
• Systems requiring lockout: electrical, hydraulic, pneumatic, mechanical, and thermal.

Fire Extinguisher Use – P.A.S.S.

• P – Pull the pin
• A – Aim at the base of the fire
• S – Squeeze the handle
• S – Sweep side to side

Refrigerant Cylinder Safety

• Cylinders are pressure vessels — never expose to excessive heat or open flame.
• Always store cylinders upright and secured.
• Never refill disposable cylinders; never exceed rated fill weight on recovery cylinders.
• Use stationary refrigerant detectors in enclosed equipment rooms to alert personnel to refrigerant leaks before concentrations become hazardous.