1|Page
NATE Certified HVAC Professional (CHP-5) Comfort
and Air Flow Certification Exam | Latest Verified
Questions and Detailed Answers
OVERVIEW DESCRIPTION
This comprehensive set of multiple choice questions is designed for the NATE Certified
HVAC Professional (CHP-5) Comfort and Air Flow exam, a specialized certification test
administered by NATE (North American Technician Excellence). As one of five focused,
job-relevant modules, this exam assesses a technician’s ability to establish and verify
customer comfort through mastery of airflow fundamentals, air balancing techniques,
system temperature and humidity diagnostics, psychrometric analysis, and duct
system evaluation. The content ensures a technician can measure, interpret, and
troubleshoot static pressure, air volume, distribution, and humidity to deliver properly
performing HVAC systems.
QUESTION 1
Which formula correctly expresses the relationship between airflow (CFM), average duct
velocity (fpm), and cross-sectional area (ft²)?
A. CFM = Velocity ÷ Area
B. CFM = Velocity × Area
C. CFM = Velocity + Area
D. CFM = Velocity - Area
CORRECT ANSWER: B
EXPERT RATIONALE: Air volume flow rate equals the average air speed multiplied by the
cross-sectional area through which it moves.
QUESTION 2
A pitot tube is used to sense which two pressures to determine air velocity?
A. Static pressure and atmospheric pressure
,2|Page
B. Total pressure and velocity pressure
C. Velocity pressure and static pressure
D. Total pressure and static pressure
CORRECT ANSWER: D
EXPERT RATIONALE: The pitot tube has a total pressure port facing the airflow and a
static pressure port perpendicular to it; the difference is velocity pressure.
QUESTION 3
What instrument measures pressure in inches of water column (in. w.c.)?
A. Anemometer
B. Manometer
C. Psychrometer
D. Velometer
CORRECT ANSWER: B
EXPERT RATIONALE: A manometer is specifically designed to measure small pressure
differences, typically in inches of water column, used for static and velocity pressures.
QUESTION 4
Air at standard conditions (0.075 lb/ft³) has a velocity pressure of 0.36 in. w.c. What is
the approximate velocity?
A. 1200 fpm
B. 2005 fpm
C. 2403 fpm
D. 2800 fpm
CORRECT ANSWER: C
EXPERT RATIONALE: V = 4005 × √(VP) = 4005 × √0.36 = 4005 × 0.6 = 2403 fpm, using
the standard air formula.
,3|Page
QUESTION 5
A technician measures a duct velocity of 900 fpm through a 12" x 12" square duct. The
airflow in CFM is:
A. 900 CFM
B. 1080 CFM
C. 675 CFM
D. 1200 CFM
CORRECT ANSWER: A
EXPERT RATIONALE: 12"x12" duct area = 1 ft²; CFM = Velocity × Area = 900 fpm × 1 ft²
= 900 CFM.
QUESTION 6
In airflow measurement, the term "CFM" stands for:
A. Cubic Feet per Minute
B. Cubic Feet per Meter
C. Centrifugal Flow Measurement
D. Cold Flow Meter
CORRECT ANSWER: A
EXPERT RATIONALE: CFM is the standard abbreviation for Cubic Feet per Minute, the
volume flow rate of air.
QUESTION 7
Which factor does NOT affect duct velocity for a given CFM?
A. Duct cross-sectional area
B. Air density
C. Duct insulation thickness
D. Duct shape
CORRECT ANSWER: C
, 4|Page
EXPERT RATIONALE: Velocity depends on area (shape matters for free area) and density
corrections, but insulation thickness does not influence the flow area.
QUESTION 8
Total external static pressure (TESP) of an air handler is defined as:
A. Supply static pressure minus return static pressure
B. Supply static pressure plus absolute return static pressure
C. Pressure drop across the filter only
D. Atmospheric pressure minus duct pressure
CORRECT ANSWER: B
EXPERT RATIONALE: TESP is the sum of the positive pressure in the supply plenum and
the absolute value of the negative pressure in the return plenum, referenced to the
equipment.
QUESTION 9
A technician measures +0.25 in. w.c. in the supply plenum and -0.15 in. w.c. in the return
plenum. The TESP is:
A. 0.10 in. w.c.
B. 0.25 in. w.c.
C. 0.40 in. w.c.
D. 0.15 in. w.c.
CORRECT ANSWER: C
EXPERT RATIONALE: TESP = 0.25 (supply positive) + |-0.15| (return negative) = 0.40 in.
w.c.
QUESTION 10
A dirty air filter will most likely cause which change in measured static pressures?
A. Return static becomes more negative and supply static decreases
B. Return static becomes less negative and supply static increases
NATE Certified HVAC Professional (CHP-5) Comfort
and Air Flow Certification Exam | Latest Verified
Questions and Detailed Answers
OVERVIEW DESCRIPTION
This comprehensive set of multiple choice questions is designed for the NATE Certified
HVAC Professional (CHP-5) Comfort and Air Flow exam, a specialized certification test
administered by NATE (North American Technician Excellence). As one of five focused,
job-relevant modules, this exam assesses a technician’s ability to establish and verify
customer comfort through mastery of airflow fundamentals, air balancing techniques,
system temperature and humidity diagnostics, psychrometric analysis, and duct
system evaluation. The content ensures a technician can measure, interpret, and
troubleshoot static pressure, air volume, distribution, and humidity to deliver properly
performing HVAC systems.
QUESTION 1
Which formula correctly expresses the relationship between airflow (CFM), average duct
velocity (fpm), and cross-sectional area (ft²)?
A. CFM = Velocity ÷ Area
B. CFM = Velocity × Area
C. CFM = Velocity + Area
D. CFM = Velocity - Area
CORRECT ANSWER: B
EXPERT RATIONALE: Air volume flow rate equals the average air speed multiplied by the
cross-sectional area through which it moves.
QUESTION 2
A pitot tube is used to sense which two pressures to determine air velocity?
A. Static pressure and atmospheric pressure
,2|Page
B. Total pressure and velocity pressure
C. Velocity pressure and static pressure
D. Total pressure and static pressure
CORRECT ANSWER: D
EXPERT RATIONALE: The pitot tube has a total pressure port facing the airflow and a
static pressure port perpendicular to it; the difference is velocity pressure.
QUESTION 3
What instrument measures pressure in inches of water column (in. w.c.)?
A. Anemometer
B. Manometer
C. Psychrometer
D. Velometer
CORRECT ANSWER: B
EXPERT RATIONALE: A manometer is specifically designed to measure small pressure
differences, typically in inches of water column, used for static and velocity pressures.
QUESTION 4
Air at standard conditions (0.075 lb/ft³) has a velocity pressure of 0.36 in. w.c. What is
the approximate velocity?
A. 1200 fpm
B. 2005 fpm
C. 2403 fpm
D. 2800 fpm
CORRECT ANSWER: C
EXPERT RATIONALE: V = 4005 × √(VP) = 4005 × √0.36 = 4005 × 0.6 = 2403 fpm, using
the standard air formula.
,3|Page
QUESTION 5
A technician measures a duct velocity of 900 fpm through a 12" x 12" square duct. The
airflow in CFM is:
A. 900 CFM
B. 1080 CFM
C. 675 CFM
D. 1200 CFM
CORRECT ANSWER: A
EXPERT RATIONALE: 12"x12" duct area = 1 ft²; CFM = Velocity × Area = 900 fpm × 1 ft²
= 900 CFM.
QUESTION 6
In airflow measurement, the term "CFM" stands for:
A. Cubic Feet per Minute
B. Cubic Feet per Meter
C. Centrifugal Flow Measurement
D. Cold Flow Meter
CORRECT ANSWER: A
EXPERT RATIONALE: CFM is the standard abbreviation for Cubic Feet per Minute, the
volume flow rate of air.
QUESTION 7
Which factor does NOT affect duct velocity for a given CFM?
A. Duct cross-sectional area
B. Air density
C. Duct insulation thickness
D. Duct shape
CORRECT ANSWER: C
, 4|Page
EXPERT RATIONALE: Velocity depends on area (shape matters for free area) and density
corrections, but insulation thickness does not influence the flow area.
QUESTION 8
Total external static pressure (TESP) of an air handler is defined as:
A. Supply static pressure minus return static pressure
B. Supply static pressure plus absolute return static pressure
C. Pressure drop across the filter only
D. Atmospheric pressure minus duct pressure
CORRECT ANSWER: B
EXPERT RATIONALE: TESP is the sum of the positive pressure in the supply plenum and
the absolute value of the negative pressure in the return plenum, referenced to the
equipment.
QUESTION 9
A technician measures +0.25 in. w.c. in the supply plenum and -0.15 in. w.c. in the return
plenum. The TESP is:
A. 0.10 in. w.c.
B. 0.25 in. w.c.
C. 0.40 in. w.c.
D. 0.15 in. w.c.
CORRECT ANSWER: C
EXPERT RATIONALE: TESP = 0.25 (supply positive) + |-0.15| (return negative) = 0.40 in.
w.c.
QUESTION 10
A dirty air filter will most likely cause which change in measured static pressures?
A. Return static becomes more negative and supply static decreases
B. Return static becomes less negative and supply static increases
