Final Nate Core Exam (2025-2026)
Questions with Correct Answers
Graded A+.
What makes a contract legal? - Answer Any verbal or written agreement.
Why should hacksaws and power saws not be used when cutting tubing or refrigerant lines? -
Answer The small shavings created by the teeth of the saw can enter the tubing and do
damage to the components of the system.
Why should tube cutters be used? - Answer They produce a square, clean cut and leave no
shavings to contaminate the system.
What can be used to cut capillary tubing? - Answer A triangular file or a knife edge file.
How should tubing be cut? - Answer It should be scored all the way around the outside and
then snapped to prevent closing of the inside diameter.
What can be used to remove a burr on the inside of tubing? - Answer Reamers and
deburrers.
What does burring cause on the inside of tubing? - Answer It can create turbulence and
pressure drop inside the piping.
What can be used on soft drawn copper to provide a bend without kinking or damaging the
tubing? - Answer Tube benders.
Spring-Type benders can only be used on what type of tubbing? - Answer Soft drawn copper
What is the purpose of a flaring tool? - Answer It allows you to join soft drawn copper tubing
without the use of a coupling.
What is the purpose of a swaging tool? - Answer A method of joining tubing without a
fitting.
,Describe the glass stem thermometer. - Answer It has a liquid filled tube marked off with a
graduated temperature scale.
What are some characteristics of a dial stem thermometer? - Answer Not quite as accurate
as the glass stem thermometer, but it is low cost and durable.
What do the glass stem thermometer and the dial stem thermometer measure? - Answer
Dry-bulb temperature.
What temperature is in relation to human comfort? - Answer Dry-bulb temperature.
What is a sling psychometer? - Answer It combines glass stem thermometers to measure
both dry-bulb and wet-bulb temperatures.
What is needed with the sling psychometer to measure temperatures? - Answer A
psychometric chart or slide rule.
What can the dry-bulb and wet-bulb temperatures be used to determine? - Answer Relative
humidity (%RH) The dew points. Other properties of the air.
What can be used to calculate the relative humidity, dew point, and other properties of the air?
- Answer The difference between the wet-bulb and the dry-bulb temperature.
Explain the effects of relative humidity. - Answer By increasing the humidity during the
heating season, the evaporation of moisture is slowed, therefore you feel warmer and vice
versa.
What is the digital psychrometer able to do? - Answer It is capable of reading dry-bulb and
wet-bulb temperature and %RH.
How do you find absolute pressure? - Answer Gauge pressure + 14.7PSI
What does a pressure gauge use as the operating element? - Answer A bourdon tube.
, What can differential pressure gauges do? - Answer They can calculate air flow. They can
help you determine how clean or dirty a coil or filter is. Provides simultaneous pressure and
flow measurements
Before you charge a system with refrigerant or after you have replaced a component or repaired
a leak, you should? - Answer Remove all air and moisture from the system.
How do you remove noncondensables, air, and moisture from a system? - Answer Drawing a
deep vacuum with a vacuum pump.
What measurement is used to measure a vacuum? - Answer Microns.
The size of a micron is? - Answer 1/1,000 mm (0.001 mm)
How many microns are in 1 in? - Answer 25,400 microns.
What can be used to measure pressures at low levels? - Answer An electronic vacuum gauge.
Different leak detection methods are? - Answer Soap bubbles. Ultrasonic devices. Electronic
leak detectors.
Which leak detection method is not as sensitive as the other methods? - Answer Soap
bubbles.
What is used to remove refrigerant from a system properly? - Answer Recovery machines.
What is used to weigh-in a refrigerant charge properly and also to record refrigerant removed
for proper record keeping under the EPA rules? - Answer Scales.
What are pressure gauges used for? - Answer To determine the static pressure in a duct
system or the pressure drop across various system components. Such as blowers, filters, coils,
and heat exchangers.
Questions with Correct Answers
Graded A+.
What makes a contract legal? - Answer Any verbal or written agreement.
Why should hacksaws and power saws not be used when cutting tubing or refrigerant lines? -
Answer The small shavings created by the teeth of the saw can enter the tubing and do
damage to the components of the system.
Why should tube cutters be used? - Answer They produce a square, clean cut and leave no
shavings to contaminate the system.
What can be used to cut capillary tubing? - Answer A triangular file or a knife edge file.
How should tubing be cut? - Answer It should be scored all the way around the outside and
then snapped to prevent closing of the inside diameter.
What can be used to remove a burr on the inside of tubing? - Answer Reamers and
deburrers.
What does burring cause on the inside of tubing? - Answer It can create turbulence and
pressure drop inside the piping.
What can be used on soft drawn copper to provide a bend without kinking or damaging the
tubing? - Answer Tube benders.
Spring-Type benders can only be used on what type of tubbing? - Answer Soft drawn copper
What is the purpose of a flaring tool? - Answer It allows you to join soft drawn copper tubing
without the use of a coupling.
What is the purpose of a swaging tool? - Answer A method of joining tubing without a
fitting.
,Describe the glass stem thermometer. - Answer It has a liquid filled tube marked off with a
graduated temperature scale.
What are some characteristics of a dial stem thermometer? - Answer Not quite as accurate
as the glass stem thermometer, but it is low cost and durable.
What do the glass stem thermometer and the dial stem thermometer measure? - Answer
Dry-bulb temperature.
What temperature is in relation to human comfort? - Answer Dry-bulb temperature.
What is a sling psychometer? - Answer It combines glass stem thermometers to measure
both dry-bulb and wet-bulb temperatures.
What is needed with the sling psychometer to measure temperatures? - Answer A
psychometric chart or slide rule.
What can the dry-bulb and wet-bulb temperatures be used to determine? - Answer Relative
humidity (%RH) The dew points. Other properties of the air.
What can be used to calculate the relative humidity, dew point, and other properties of the air?
- Answer The difference between the wet-bulb and the dry-bulb temperature.
Explain the effects of relative humidity. - Answer By increasing the humidity during the
heating season, the evaporation of moisture is slowed, therefore you feel warmer and vice
versa.
What is the digital psychrometer able to do? - Answer It is capable of reading dry-bulb and
wet-bulb temperature and %RH.
How do you find absolute pressure? - Answer Gauge pressure + 14.7PSI
What does a pressure gauge use as the operating element? - Answer A bourdon tube.
, What can differential pressure gauges do? - Answer They can calculate air flow. They can
help you determine how clean or dirty a coil or filter is. Provides simultaneous pressure and
flow measurements
Before you charge a system with refrigerant or after you have replaced a component or repaired
a leak, you should? - Answer Remove all air and moisture from the system.
How do you remove noncondensables, air, and moisture from a system? - Answer Drawing a
deep vacuum with a vacuum pump.
What measurement is used to measure a vacuum? - Answer Microns.
The size of a micron is? - Answer 1/1,000 mm (0.001 mm)
How many microns are in 1 in? - Answer 25,400 microns.
What can be used to measure pressures at low levels? - Answer An electronic vacuum gauge.
Different leak detection methods are? - Answer Soap bubbles. Ultrasonic devices. Electronic
leak detectors.
Which leak detection method is not as sensitive as the other methods? - Answer Soap
bubbles.
What is used to remove refrigerant from a system properly? - Answer Recovery machines.
What is used to weigh-in a refrigerant charge properly and also to record refrigerant removed
for proper record keeping under the EPA rules? - Answer Scales.
What are pressure gauges used for? - Answer To determine the static pressure in a duct
system or the pressure drop across various system components. Such as blowers, filters, coils,
and heat exchangers.
