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100+ Free HVAC Air Distribution Practice Questions

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2026 Statistics

Key Facts: HVAC Air Distribution Exam

70%

Minimum score generally required to pass an HVAC Excellence Professional exam

HVAC Excellence Professional certification guidance

Q = 1.08 x CFM x delta-T

Air-side sensible-heat formula in BTU per hour

HVAC air-side load calculation reference

0.68 and 4.5

Latent-heat and total-heat constants for the air-side formulas

HVAC psychrometric calculation reference

Closed book

The Professional Air Distribution exam is a proctored closed-book written test

HVAC Excellence Professional certification format

2+ years

Documented field experience generally required for Professional-level certification

HVAC Excellence Professional certification eligibility

Manual D

ACCA standard used for residential duct design and friction-rate sizing

ACCA Manual D residential duct design

TP = SP + VP

Total pressure equals static pressure plus velocity pressure in a duct

HVAC air-distribution pressure fundamentals

100

Free original practice questions here

OpenExamPrep

The HVAC Excellence Professional Air Distribution exam is a closed-book, proctored multiple-choice written test of roughly 100 questions for experienced HVAC technicians. It covers airflow and psychrometrics (including Q = 1.08 x CFM x delta-T), static pressure and the fan laws, ACCA Manual D duct design and sizing, registers and air balancing (TAB), and blowers and ventilation. A minimum of 70 percent is generally required to pass, exams run about 1.5 to 3 hours, and professional-level certification usually requires two or more years of documented field experience. This 100-question bank provides original, calculation-rich practice across all of those air-side topics with full answer explanations.

Sample HVAC Air Distribution Practice Questions

Try these sample questions to test your HVAC Air Distribution exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Using the air-side sensible-heat formula Q = 1.08 x CFM x delta-T, how much sensible heat is added by a furnace delivering 1,200 CFM with a 50 degF temperature rise?
A.54,000 BTU/hr
B.64,800 BTU/hr
C.60,000 BTU/hr
D.120,000 BTU/hr
Explanation: Q = 1.08 x 1,200 x 50 = 64,800 BTU/hr. The constant 1.08 converts CFM and a Fahrenheit temperature difference into sensible BTU per hour for standard air.
2In a duct, the total pressure is best described by which relationship?
A.Total pressure = static pressure - velocity pressure
B.Total pressure = static pressure + velocity pressure
C.Total pressure = velocity pressure - static pressure
D.Total pressure = static pressure x velocity pressure
Explanation: Total pressure (TP) equals static pressure (SP) plus velocity pressure (VP). Static pressure pushes outward on the duct walls, while velocity pressure is the energy of the moving air; their sum is total pressure.
3What does external static pressure (ESP) represent for a residential air handler?
A.The pressure drop across the indoor coil only
B.The total static pressure the blower must overcome in the duct system outside the equipment cabinet
C.The atmospheric pressure surrounding the unit
D.The velocity pressure measured at the supply diffuser
Explanation: External static pressure is the total resistance the blower must overcome in the duct system, registers, grilles and filter that are external to the cabinet. It is typically the sum of the supply-side and return-side static readings and is compared to the blower's rated maximum ESP.
4According to the fan laws, if a blower's speed is increased from 800 RPM to 1,000 RPM, the airflow (CFM) will:
A.Increase by the ratio 1,000/800, about 25 percent
B.Increase by the square of the ratio, about 56 percent
C.Increase by the cube of the ratio, about 95 percent
D.Stay the same because CFM is independent of RPM
Explanation: The first fan law states airflow varies directly with fan speed. CFM new = CFM old x (1,000/800) = 1.25 times the original, a 25 percent increase. Pressure varies with the square and horsepower with the cube of the speed ratio.
5Which instrument is most commonly used to measure static pressure in a residential duct system?
A.Clamp-on ammeter
B.Magnehelic or digital manometer
C.Sling psychrometer
D.Refrigerant micron gauge
Explanation: Static pressure is measured with a magnehelic gauge or a digital manometer connected to a static-pressure tip inserted into the duct. Readings are given in inches of water column (in. w.c.).
6A cooling system must remove 36,000 BTU/hr of sensible heat with a coil delta-T of 20 degF. Using Q = 1.08 x CFM x delta-T, what airflow is required?
A.1,200 CFM
B.1,667 CFM
C.1,800 CFM
D.900 CFM
Explanation: Rearranging, CFM = Q / (1.08 x delta-T) = 36,000 / (1.08 x 20) = 36,000 / 21.6 = 1,667 CFM. This is the airflow needed to carry the sensible load at the stated temperature drop.
7Which formula correctly relates airflow, velocity and duct cross-sectional area?
A.CFM = velocity (fpm) x area (sq ft)
B.CFM = velocity (fpm) / area (sq ft)
C.CFM = velocity (fpm) + area (sq ft)
D.CFM = area (sq ft) / velocity (fpm)
Explanation: Volumetric airflow equals velocity times area: CFM = fpm x sq ft. For example, 1,000 fpm through a 2 sq ft duct moves 2,000 CFM. This relationship underlies duct traverse and outlet-velocity calculations.
8Which standard is the recognized method for residential duct system design?
A.ACCA Manual J
B.ACCA Manual D
C.ACCA Manual S
D.ASHRAE 90.1
Explanation: ACCA Manual D is the standard for residential duct design. Manual J calculates the load, Manual S selects the equipment, and Manual D then sizes the duct system based on the equipment's available static pressure.
9In the friction-rate method of Manual D, the friction rate is found by:
A.Dividing available static pressure by the total effective length and multiplying by 100
B.Multiplying the duct velocity by the duct area
C.Adding all the equivalent lengths of fittings together
D.Dividing the CFM by the duct diameter
Explanation: Friction rate (in. w.c. per 100 ft) = (available static pressure / total effective length) x 100. Available static pressure is the blower ESP minus component losses, and total effective length includes straight duct plus the equivalent lengths of fittings.
10What is the purpose of the 'equivalent length' assigned to a duct fitting such as an elbow or takeoff?
A.To convert the fitting's turbulence loss into an equal length of straight duct for sizing
B.To measure the physical length of the fitting in inches
C.To determine the weight of sheet metal needed
D.To set the insulation R-value of the fitting
Explanation: Equivalent length expresses a fitting's added friction loss as the length of straight duct that would cause the same pressure drop. Adding equivalent lengths of all fittings to the straight-duct length gives the total effective length used to find the friction rate.

About the HVAC Air Distribution Exam

The HVAC Excellence Professional Air Distribution exam is a closed-book, proctored, multiple-choice written test for experienced technicians who design, install, measure and troubleshoot air-side HVAC systems. It covers airflow fundamentals and psychrometrics, including the air-side sensible-heat formula Q = 1.08 x CFM x delta-T; static pressure and system performance, including external static pressure and the fan laws; duct design and sizing using ACCA Manual D and the friction-rate method; registers, grilles and diffusers; testing, adjusting and balancing (TAB); blowers and motors; and ventilation and indoor air quality. Professional-level certification generally requires two or more years of documented field experience, and a minimum score of 70 percent is needed to pass.

Assessment

Closed-book multiple-choice written exam of roughly 100 questions covering airflow fundamentals, static pressure and system performance, duct design and sizing, registers and balancing, and blowers and ventilation.

Time Limit

Professional-level HVAC Excellence exams generally run between 1.5 and 3 hours of proctored testing time.

Passing Score

A minimum score of 70 percent is generally required to pass.

Exam Fee

Professional-level certification exams typically cost about $60 to $100 each in 2025-2026; the exact fee is set by HVAC Excellence and the proctoring site. (HVAC Excellence (a division of the ESCO Group))

HVAC Air Distribution Exam Content Outline

22%

Static Pressure and System Performance

Total pressure equals static plus velocity pressure; external static pressure (ESP) across a packaged air handler; measuring static with a manometer or magnehelic gauge; reading the fan and system curves; and applying the fan laws, where CFM varies directly with RPM, static pressure with the square of RPM, and horsepower with the cube of RPM.

22%

Duct Design and Sizing

ACCA Manual D as the residential duct-design standard, the available static pressure and total effective length used to set a friction rate, the equal-friction method, equivalent length of fittings, sizing round and rectangular duct with the friction chart or ductulator, and the effect of aspect ratio on rectangular duct friction.

20%

Airflow Fundamentals and Psychrometrics

Converting between CFM and velocity (CFM = velocity x area), sensible, latent and total heat, the air-side sensible-heat formula Q = 1.08 x CFM x delta-T, the latent (0.68) and total-heat (4.5) constants, solving for required CFM, and temperature rise across a furnace or drop across a cooling coil.

18%

Registers, Grilles, Diffusers and Air Balancing

Selecting supply outlets by throw, spread, drop and face velocity; NC sound ratings; return grilles and net free area; and testing, adjusting and balancing (TAB) using proportional balancing, a flow hood (balometer) and a Pitot-tube duct traverse to find average velocity and CFM.

18%

Blowers, Motors, Ductwork and IAQ

Forward-curved versus backward-inclined centrifugal blowers, belt-drive versus direct-drive and ECM motors, brake horsepower, duct materials (galvanized sheet metal, flex and ductboard), dampers (volume, balancing, fire and smoke), SMACNA construction and sealing, duct R-value, and ventilation and filtration per ASHRAE 62.2 and MERV ratings.

How to Pass the HVAC Air Distribution Exam

What You Need to Know

  • Passing score: A minimum score of 70 percent is generally required to pass.
  • Assessment: Closed-book multiple-choice written exam of roughly 100 questions covering airflow fundamentals, static pressure and system performance, duct design and sizing, registers and balancing, and blowers and ventilation.
  • Time limit: Professional-level HVAC Excellence exams generally run between 1.5 and 3 hours of proctored testing time.
  • Exam fee: Professional-level certification exams typically cost about $60 to $100 each in 2025-2026; the exact fee is set by HVAC Excellence and the proctoring site.

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

HVAC Air Distribution Study Tips from Top Performers

1Memorize the three air-side constants cold: 1.08 for sensible heat, 0.68 for latent heat and 4.5 for total heat, since the exam is closed book and these appear in many calculation items.
2Practice rearranging Q = 1.08 x CFM x delta-T to solve for any one variable; many questions give two of the three and ask for the third, such as finding required CFM for a known sensible load and delta-T.
3Drill the fan laws as ratios: CFM is proportional to RPM, static pressure to RPM squared and horsepower to RPM cubed, so a small speed increase causes a large jump in power.
4Understand external static pressure: learn to add up the supply and return static readings across an air handler and compare to the rated maximum ESP on the blower table.
5Work through Manual D logic: available static pressure divided by total effective length (per 100 feet) gives the friction rate that you carry into the friction chart or ductulator.
6Know your balancing tools and terms: a flow hood (balometer) reads diffuser CFM directly, a Pitot-tube traverse finds average duct velocity, and proportional balancing sets branches relative to each other before final trim.

Frequently Asked Questions

Is the HVAC Excellence Air Distribution exam open or closed book?

It is a closed-book, proctored written exam. No notes, charts or reference materials are permitted during the test, so candidates must know the air-side formulas and procedures.

How many questions are on the Air Distribution exam and what score do I need?

Professional-level HVAC Excellence exams contain roughly 50 to 100 multiple-choice questions; the Air Distribution exam is about 100 questions, and a minimum score of 70 percent is generally required to pass.

What is the air-side heat formula tested on this exam?

The sensible-heat formula is Q = 1.08 x CFM x delta-T, where Q is sensible BTU per hour, CFM is airflow and delta-T is the temperature difference. The latent constant is 0.68 and the total-heat constant is 4.5.

Do the fan laws appear on the exam?

Yes. The fan laws state that airflow (CFM) varies directly with fan RPM, static pressure varies with the square of RPM, and brake horsepower varies with the cube of RPM.

What duct-design method does the exam expect?

Residential duct sizing follows ACCA Manual D, which uses available static pressure and total effective length to set a friction rate, then sizes duct with a friction chart or ductulator using the equal-friction method.

Are these official HVAC Excellence exam questions?

No. These are original OpenExamPrep practice questions modelled on the air-distribution body of knowledge. HVAC Excellence and the ESCO Group provide official preparation and certification separately.