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NATE_CORE NEC 2023

NATE Core Practice Test 7

This practice test covers temperature and humidity measurement from the NATE Core exam blueprint. You will see questions on dry bulb and wet bulb temperature, relative humidity, the psychrometric chart, and the sling psychrometer.

TOPICS COVERED

NATE Core

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Frequently Asked Questions

Yes — completely free with no signup required. Every question includes a full explanation of the correct answer.

Two: the NATE Core exam plus at least one specialty exam (for example AC Service, Heat Pump Service, or Air Distribution Service). You can take them on the same day or separately.

The Core exam has 50 questions and each installation or service specialty exam has 100 questions. You need 70% on each to pass — 35 of 50 on Core and 70 of 100 on a specialty. Check natex.org for the current format before you book.

NATE certification lasts two years. To renew, you submit 16 hours of continuing education or retake the specialty exam before your certification expires.

No. These are independent practice tests written to match the published NATE exam topics. They are not official NATE exam questions.

Exam Tip: Remember that the wet bulb reading is always equal to or lower than the dry bulb reading. The bigger the gap between them, the lower the relative humidity.

30

Questions

30 min

Time

70%

Pass

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NATE Core Practice Test 7 — Question List

Question 1: What does "dry bulb temperature" mean?

The temperature read using a moistened thermometer bulb
The temperature of refrigerant only
The normal air temperature reading, taken with an ordinary thermometer
The temperature of a solid surface only

Question 2: What does "wet bulb temperature" mean?

The temperature setting on a humidifier
The temperature of water in a drain pan
The average of the high and low temperature for the day
The temperature read using a thermometer with a wet, moistened bulb, affected by evaporative cooling

Question 3: What does "relative humidity" measure?

The amount of moisture in the air compared to the maximum it could hold at that temperature
The temperature of the air only
The pressure of refrigerant vapor
The total weight of water in a home

Question 4: How are dry bulb and wet bulb temperature readings used together?

They are added together to get the BTU rating of a system
They are compared, often with a psychrometric chart or sling psychrometer, to determine relative humidity
They are used only to measure refrigerant pressure
They have no relationship to each other

Question 5: What is a "sling psychrometer" used for?

Measuring refrigerant pressure
Cutting copper tubing
Taking wet bulb and dry bulb readings to determine humidity
Testing electrical voltage

Question 6: In normal conditions, how does the wet bulb temperature reading compare to the dry bulb temperature reading of the same air?

There is no relationship between the two readings
The wet bulb reading is always higher than the dry bulb reading
They are always exactly the same, with no exceptions
The wet bulb reading is equal to or lower than the dry bulb reading

Question 7: What does it mean if relative humidity is at 100%?

The air is holding the maximum amount of moisture it can hold at that temperature
The air temperature is at its highest possible point
The wet bulb thermometer will always read higher than the dry bulb
The air contains no moisture at all

Question 8: What is a psychrometric chart used for?

Showing the wiring diagram of a thermostat
Showing the relationship between temperature, humidity, and other properties of air
Showing refrigerant pressure and temperature relationships only
Showing the layout of ductwork in a building

Question 9: What is the basic purpose of a thermometer?

To measure electrical resistance
To measure refrigerant charge
To measure temperature
To measure air pressure

Question 10: Why does evaporation cause the wet bulb thermometer to read a lower temperature than the dry bulb thermometer?

Wet bulb thermometers are simply less accurate than dry bulb thermometers
Water always freezes on the wet bulb wick
The wet wick blocks all heat from reaching the thermometer
Evaporating water absorbs heat from the thermometer bulb, cooling it

Question 11: A technician takes a reading and finds that the wet bulb and dry bulb temperatures are exactly the same. What does this tell the technician?

The relative humidity is at or near 100%
The air temperature is below freezing
There is no humidity in the air at all
The thermometer is broken

Question 12: A technician notices a large difference between the dry bulb and wet bulb readings. What does this generally indicate?

Higher relative humidity in the air
Lower relative humidity in the air
The thermometers need to be replaced
The refrigerant charge is low

Question 13: Besides traditional glass thermometers, what other common type of thermometer might a technician use in the field?

A manifold gauge
A tubing cutter
A digital thermometer with a probe
A torque wrench

Question 14: In what units is relative humidity typically expressed?

In BTUs
In pounds per square inch
In degrees Fahrenheit
As a percentage

Question 15: If a technician knows both the dry bulb temperature and the wet bulb temperature, what can a psychrometric chart help them find?

The relative humidity and other properties of the air
The electrical voltage of the circuit
The size of the ductwork needed
The exact refrigerant type in the system

Question 16: When a weather report gives today's outdoor temperature, which type of temperature reading is this most similar to?

Wet bulb temperature
Dry bulb temperature
Latent temperature
Saturation temperature only

Question 17: Why might a technician measure both temperature and humidity when evaluating how well a cooling system is performing?

Humidity has no effect on how a system performs
Humidity is only relevant to heating systems, not cooling systems
The system needs to manage both temperature (sensible heat) and humidity (latent heat) for good performance
Only the wet bulb reading needs to be checked; dry bulb is not important

Question 18: Which type of thermometer reading requires a wet, moistened wick around the sensing bulb?

Digital temperature
Dry bulb
Surface temperature
Wet bulb

Question 19: On a very humid summer day, would the gap between the dry bulb and wet bulb temperature readings typically be larger or smaller compared to a dry day?

Smaller, because less evaporation happens when the air is already humid
It stays exactly the same no matter the humidity
The wet bulb reading would be higher than the dry bulb reading
Larger, because humid air always evaporates faster

Question 20: Which tool would a technician most likely use to check the surface temperature of a suction line?

Manifold gauge
Clip-on or probe thermometer
Torque wrench
Nut driver

Question 21: Why can the same amount of moisture in the air result in different relative humidity readings at different temperatures?

Relative humidity never changes with temperature
Moisture content and temperature are unrelated to relative humidity
Warmer air can hold more moisture, so the same moisture level is a lower percentage of the warmer air's capacity
Colder air can always hold more moisture than warm air

Question 22: A technician reads 75 degrees F on a standard thermometer with no wet wick involved. What kind of reading is this?

Latent temperature
Wet bulb temperature
Relative humidity
Dry bulb temperature

Question 23: What general concept does "dew point" describe?

The temperature at which air becomes fully saturated and moisture begins to condense
The pressure at which refrigerant boils
The R-value of insulation
The exact BTU rating of a furnace

Question 24: Which two temperature readings are needed to determine relative humidity using a sling psychrometer?

Supply and return air temperature
Dry bulb and wet bulb temperature
High-side and low-side pressure
Indoor and outdoor temperature

Question 25: A technician records a dry bulb reading of 80 degrees F and a wet bulb reading of 67 degrees F, a noticeable gap between the two. What does this gap generally suggest about the relative humidity?

The relative humidity is at exactly 100%
The relative humidity cannot be estimated from these two readings
The relative humidity is less than 100%, and a noticeable gap suggests it is not extremely high
The air contains no moisture at all

Question 26: What is the main difference between measuring air temperature and measuring the surface temperature of a pipe?

Air temperature can only be measured with a wet bulb thermometer
There is no difference; both use the exact same method
Surface temperature can only be measured with a manifold gauge
Air temperature is measured with the sensor in the airstream; surface temperature is measured with the sensor touching or clamped to the pipe

Question 27: True or False: The wet bulb temperature reading can never be higher than the dry bulb temperature reading for the same air sample.

True
False, there is no relationship between the two
False, it depends only on the thermometer brand
False, wet bulb is always higher

Question 28: Why do HVACR technicians measure both temperature and humidity when checking system performance?

Because only humidity actually matters
Because both affect comfort and system performance together
Because temperature and humidity are the exact same measurement
Because it is required by the manufacturer's paint warranty

Question 29: Why does a technician swing a sling psychrometer through the air before taking a reading?

To warm up the thermometers before use
To mix the refrigerant inside the unit
To move air across the wet wick so it can evaporate properly and give an accurate wet bulb reading
To clean dust off the thermometers

Question 30: What two things does a technician need to determine relative humidity using a psychrometric chart?

The R-value and the BTU rating
The refrigerant type and the system's tonnage
The voltage and the amperage
The dry bulb temperature and the wet bulb temperature

EXAM CARD NATE_CORE

Questions30

Time limit30 min

Pass score70%

Code editionNEC 2023

DifficultyIntermediate

Last reviewedJun 2026

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Source: NEC 2026 (NFPA 70)