Trades Exam Prep

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - How schematics represent all switches and contacts in their de-energized shelf state on NATE exam diagrams - The operational differences between line voltage loads and low voltage control circuits - Terminal identification standards for thermostats and compressor windings - The difference between logical ladder schematics and physical pictorial wiring diagrams - H...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Core 24-volt thermostat terminal assignments for R, C, W, Y, and G in heating and cooling control loops - Crucial differences between O and B reversing valve energization logic for heat pump systems - Thermostat fan control behavior in gas furnaces versus electric heating and heat pump applications - Structural distinctions b...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Distinction between relays, contactors, and sequencers in HVAC control applications - How normally open and normally closed contacts behave in schematic diagrams - Staging electric heating elements and fan operation using timing sequencers - Function and series wiring of high limits, pressure switches, and safety interlocks - Step-by-step method to trace l...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - How to calculate maximum secondary amperage using transformer VA ratings and turns ratio formulas - The impact of incorrect primary multi-tap wiring on low-voltage output and contactor reliability - Requirements for secondary grounding and Class 2 overcurrent protection under NEC Article 725 - How to accurately interpret meter readings across open fuses and i...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Key operational differences between shaded-pole, PSC, and ECM motors tested on the NATE exam. - How to calculate resistance across common, run, and start terminals to identify compressor connections. - Operating principles of potential relays versus current relays, including back-EMF pickup and contact states. - Critical rules for capacitor replacement, microfarad s...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - How frequency and inductance create counter electromotive force and inductive reactance in HVAC motor windings. - How to apply the ELI the ICE man mnemonic to remember voltage and current phase relationships in inductive and capacitive circuits. - The distinction between pure resistance, inductive reactance, and total circuit impedance measured in o...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Voltage drop rules for closed versus open switches in series control circuits - How current and voltage behave across parallel loads versus series safety devices - Resistance calculations for series and parallel HVAC electrical paths - Troubleshooting symptoms of open circuits, short circuits, and high-resistance connections - The operation and electrical b...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - How to apply Ohm's Law and Watt's Law to calculate voltage, current, resistance, and power in HVAC circuits. - Why a ten percent drop in voltage results in a nineteen percent loss in resistive heating power output. - How to interpret voltage drop readings across closed contactor contacts to identify high-resistance f...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - How to correctly convert temperature between Fahrenheit, Celsius, and absolute Rankine scales on NATE questions. - The vital difference between PSIG and PSIA and when to add 14.7 for gas law equations. - How to calculate airflow CFM from electric heat kilowatts using sensible heat formulas. - A units-first calculation strategy using t...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Key differences between complete and incomplete combustion and primary versus secondary air requirements. - Unconfined space volume rules per NFPA 54 requiring 50 cubic feet per 1,000 BTU per hour total input. - Flame diagnostics for identifying yellow tipping, floating flames, and cracked heat exchanger indicators. - Venting system classifications for Category I and C...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Suction line velocity requirements to ensure proper oil return to the compressor crankcase. - Why liquid lines are generally uninsulated except when passing through high temperature ambient spaces. - Trap placement rules for vertical suction risers to prevent compressor oil starvation. - The critical role of dry nitrogen purging during brazing t...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - How to calculate evaporator superheat, total superheat, and condenser subcooling using temperature readings and P-T pressure conversions. - What high and low superheat or subcooling values reveal about system charge, liquid floodback, and operating efficiency. - How to choose between superheat charging for fixed orifice devices and subcooling charging for TXV s...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - How saturation temperature, boiling, and condensing function at thermodynamic equilibrium on NATE exam questions - The critical distinction between gauge pressure in PSIG and absolute pressure in PSIA, including atmospheric math traps - Practical high-side and low-side system examples calculating superheat and subcooling using P-T charts - Why accurate refrigerant identification a...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Tracing refrigerant temperature, pressure, and phase changes through all four major cycle components - How subcooling and superheat are measured and applied during system charging and troubleshooting - Common NATE exam traps regarding compressor inlet conditions and thermostatic expansion valve behavior - The role of flash gas at the metering device o...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Differentiation between conduction, convection, and radiation heat transfer modes - Distinction between sensible heat and latent phase changes during HVAC diagnostics - Definition of BTUs and conversion of heat load to tons of refrigeration - Calculation of air-side sensible capacity using measured CFM and temperature split - Identification of common exam t...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - CAT rating requirements and meter safety protocols for NATE certification - Proper clamp meter usage to avoid false zero amp readings on dual conductors - Temperature and psychrometric sensor field calibration using ice baths and distilled water - Vacuum micron gauge placement and manometer zeroing procedures for accurate diagnostics - NEC 110.14(D...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - How OSHA 1910.147 lockout and tagout procedures require testing for zero energy before touching electrical components. - The 4-to-1 angle ratio and 3-foot landing extension requirement for ladders under OSHA 1926.1053. - Key hazards of refrigerant exposure and oxygen displacement in confined spaces per OSHA 1926 Subpart AA. - Proper PPE standards, including ANSI Z...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Five separate 30-question modules that make up the NATE CHP-5 certification pathway - Key differences between the CHP-5 pathway and the traditional Core plus Specialty exam format - How to accurately calculate total external static pressure on the Comfort and Airflow exam - Common exam traps involving NEC voltage drop rules a...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Key recovery efficiency numbers (90% active vs. 80% passive) and the crucial 80% fill limit for recovery cylinders. - The 2026 update to leak rate rules, lowering the trigger threshold from 50 lbs to 15 lbs for HFC systems. - The critical distinction between the Montreal Protocol (Ozone/ODP) and the Kigali Amendment/AIM Act (Climate/GWP). ...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Understand that recovered refrigerant oil is regulated waste and must be disposed of properly, not in drains or regular trash. - Learn that a positive acid test on compressor oil is a definitive sign of a motor burnout, indicating the presence of corrosive acids. - Master the correct procedure after a c...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Always recover refrigerant to 0 psig before applying heat or opening a system to prevent phosgene gas formation and explosions. - During brazing, you must flow a low-pressure purge of dry nitrogen through the tubing to prevent internal oxidation and scale. - Never use compressed air or oxygen for pressure testing; only u...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - A micron gauge, not a manifold gauge, is required to measure a deep vacuum and confirm moisture removal. - For high-pressure systems with HFC refrigerants and POE oil, the required evacuation level is below 500 microns. - Moisture left in a system with POE oil can react to form damaging hydrochloric and h...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - The critical difference between the R-22 phaseout (for ozone, completed) and the HFC phase-down (for climate, ongoing). - Why January 1, 2020, is a key date marking the end of new R-22 production and import. - How the AIM Act of 2020 mandates an 85% reduction of HFCs by 2036 to address their high Global Warming P...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Why refrigerants, being heavier than air, create a significant asphyxiation risk in confined spaces by displacing oxygen. - The critical safety rule of recovering all refrigerant before brazing to prevent the formation of lethal phosgene gas from chlorinated refrigerants. - How direct contact with liquid refrigerant causes severe frostbite and why p...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - The EPA 608 exam consists of four independent 25-question sections: Core, Type I, Type II, and Type III. - A passing score of 72%, which is 18 out of 25 correct answers, is required for each section in a standard proctored exam. - The Core section is mandatory and must be passed to receive any t...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - That Universal Certification is earned by passing the Core, Type I, Type II, and Type III sections, not by taking a separate 'Universal' exam. - Each of the four exam sections contains 25 multiple-choice questions, and a passing score is 72%, or 18 questions correct. - Passing the Core section by itself does not g...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Why you must always break the vacuum on a low-pressure chiller with refrigerant vapor before adding any liquid. - The specific refrigerant saturation temperature, 36°F, that must be reached with vapor before liquid charging can begin. - How introducing liquid refrigerant into a deep vacuum can flash-freeze and rupture water tubes, a...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Why a dedicated recovery unit with a 10 psig high-pressure cutout is required for low-pressure systems. - The correct recovery sequence is always vapor first, then liquid, to prevent water in the chiller tubes from freezing. - How circulating warm water helps boil refrigerant out of the system's oil for a more c...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - That purge units are required on low-pressure chillers because they operate in a vacuum, which causes leaks to draw air and moisture into the system. - Why non-condensable gases accumulate at the top of the condenser, where the purge unit is located to remove them. - That excessive or frequent purge u...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Why leaks in low-pressure chillers draw air and moisture INTO the system instead of venting refrigerant out. - That the primary indicator of a leak in a low-pressure system is high condenser (head) pressure. - The function of a purge unit is to continuously remove non-condensables that enter through leaks. - H...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - How to identify Type III appliances and their associated low-pressure refrigerants like R-11 and R-123. - The critical concept that low-pressure systems operate in a vacuum, causing leaks to pull air and moisture inward. - The primary function of a purge unit and why its excessive operation indicates a system leak. ...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - To use the push-pull method for rapid liquid recovery from large systems and standard vapor-liquid recovery for smaller ones. - The critical difference between the 0 psig recovery target for opening a system versus the deep vacuum required for post-repair evacuation. - Why you must never mix refrigerants in a recovery cylinder o...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Why R-410A systems mandate the use of synthetic POE (polyolester) oil. - How the hygroscopic nature of POE oil leads to the formation of corrosive acids and sludge when exposed to moisture. - The critical exam requirement of pulling a deep vacuum to 500 microns or lower, verified by a micron g...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Why R-410A's operating pressure is 50-70% higher and poses a rupture risk to R-22 components. - The critical incompatibility between R-22's mineral oil and R-410A's synthetic POE oil. - Why POE oil's hygroscopic nature (moisture absorption) is a key service consideration. - That metering devices are specifically calibrated a...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - R-744 (CO2) is the primary very-high-pressure refrigerant on the EPA 608 exam, with operating pressures far exceeding traditional systems. - Servicing R-744 systems requires specialized equipment and gauges rated for pressures that can exceed 2000 psig. - The critical temperature for R-744 is 87.8°F; above this point, the system operates in a transcritical st...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - That Type II certification covers high-pressure (R-22, R-410A) and very-high-pressure (R-744 CO2) appliances. - Why R-410A's higher operating pressures require dedicated gauges, hoses, and recovery equipment rated for that service. - The proper procedure for charging zeotropic blends like R-407C as a liquid to prevent fractionation. - The m...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - The critical 1995 manufacturing year that distinguishes R-12 (CFC) systems from R-134a (HFC) systems on the exam. - The environmental trade-offs between R-12 (high ODP), R-134a (high GWP), and R-600a (low GWP). - Why the primary safety concern for modern hydrocarbon refrigerants like R-600a is their A3 flammability c...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Why heating a recovery cylinder creates a pressure differential to speed up refrigerant recovery. - The only safe, EPA-approved heating methods, such as warm water baths and dedicated electric heat blankets. - Why you must never use an open flame, like a torch, due to severe explosion risk and toxic gas f...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Recovery cylinders must never be filled beyond 80% of their capacity by weight to allow for thermal expansion. - Always use a scale and know the cylinder's tare weight (TW) and water capacity (WC) to calculate the maximum fill level. - Overfilling can cause hydrostatic pressure, leading to a violent and dangerous c...

This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams. In this episode you will learn: - Self-contained recovery machines must be certified to recover 90% of the refrigerant from a small appliance if its compressor is operational. - The 80% recovery standard applies only when a small appliance's compressor is inoperative. - Do not confuse the machine's recovery efficiency (90%/80%) with the required field evacuation level of a 4-inch mercury v...