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HVAC Fundamentals: Core Science (NATE)
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What you’ll learn This quiz covers the core science behind HVAC, including heat transfer, pressure relationships, and temperature behavior. The goal is to make the system feel logical instead of memorized. Here is a breakdown of the core science and fundamental areas covered in the exam: 1. Basic Science Fundamentals Heat Transfer: Understanding how heat moves via conduction, convection, and radiation. Temperature and Humidity: Measuring, understanding dew point, and how moisture affects human comfort. Pressure: Understanding pressure-temperature relationships, atmospheric pressure, and... Show more
HVAC Fundamentals: Core Science (NATE)
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10 Questions

1. (Difficulty: easy) What is the compression ratio for a system with suction pressure of 69 PSIG and discharge pressure of 278 PSIG?
2. (Difficulty: medium) A 24V control transformer has 240V on the primary side and 24V on the secondary side. What is the transformer turns ratio?
3. (Difficulty: medium) A return-air duct carries 1,200 CFM. The supply registers deliver a total of 900 CFM. Ignoring measurement error, what is the most likely conclusion?
4. (Difficulty: medium) Air entering an evaporator is 80°F dry-bulb and leaves at 58°F dry-bulb. Assuming airflow stays constant, what is the sensible temperature change across the coil?
5. (Difficulty: medium) A standard 15A circuit breaker is protecting a 120V circuit. A worker contacts both conductors simultaneously. The current through the worker is 85 mA. Will the breaker protect the worker?
6. (Difficulty: medium) A technician measures 240 volts and 10 amps on a single-phase electric heater circuit. What is the power draw?
7. (Difficulty: medium) What is the synchronous speed of a 4-pole, 60 Hz single-phase motor?
8. (Difficulty: easy) If the evaporator saturated temperature is 40°F and the suction line temperature at the outlet is 52°F, what is the system superheat?
9. (Difficulty: easy) A 3-ton residential cooling system is designed for 400 CFM per ton. What total airflow should the blower deliver?
10. (Difficulty: easy) If the condensing saturated temperature is 105°F and the liquid line temperature leaving the condenser is 93°F, what is the subcooling?