NADCA (National Air Duct Cleaners
Association) study guide based on the
updated 2026/2027 syllabus
ACR (Air Systems Cleaning Specialist) certification, including safety,
inspection, containment, methodologies, equipment, and industry standards
(NADCA 2026/2027).
Section 1: General Industry Knowledge & Standards
1. What is the primary standard that dictates the recommended practices for
HVAC system cleaning in the United States?
A) IICRC S500
B) ANSI/ACCA 4 QI
C) ANSI/ASHRAE Standard 62.1
D) NADCA ACR Standard
ANSWER ✓ D) NADCA ACR Standard
2. According to the updated 2026/2027 syllabus, what is the minimum required
negative pressure differential when connecting a containment device to an HVAC
system?
A) 0.05 inches of water column (in. w.c.)
B) 0.10 inches of water column (in. w.c.)
C) 0.25 inches of water column (in. w.c.)
D) 0.50 inches of water column (in. w.c.)
ANSWER ✓ A) 0.05 inches of water column (in. w.c.)
3. Which organization’s standards are primarily referenced by NADCA for safety
protocols regarding lockout/tagout?
A) EPA
B) OSHA
C) NFPA
D) ASTM
ANSWER ✓ B) OSHA
,4. What does the acronym "HVAC" stand for in the context of air systems
cleaning?
A) High Velocity Air Circulation
B) Heating, Ventilating, and Air Conditioning
C) Horizontal Vertical Air Control
D) High Volume Air Conveyance
ANSWER ✓ B) Heating, Ventilating, and Air Conditioning
5. The primary goal of a mechanical cleaning process in HVAC systems is to:
A) Disinfect the ductwork using chemical sprays.
B) Seal leaks in the ductwork to improve efficiency.
C) Dislodge and remove debris from the interior surfaces.
D) Increase the static pressure of the blower motor.
ANSWER ✓ C) Dislodge and remove debris from the interior surfaces.
Section 2: Containment & Negative Pressure
6. When performing cleaning on a multi-zone system, what is the critical
requirement regarding containment?
A) Only clean one zone per day.
B) Containment must be established on each zone individually.
C) The entire system must be cleaned simultaneously.
D) Only the main trunk line requires containment.
ANSWER ✓ B) Containment must be established on each zone individually.
7. What is the purpose of a "bubble" or "source" containment?
A) To prevent debris from exiting the HVAC equipment during cleaning.
B) To protect the surrounding furniture from cleaning tools.
C) To allow the technician to monitor airflow visually.
D) To increase the temperature inside the work area.
ANSWER ✓ A) To prevent debris from exiting the HVAC equipment during
cleaning.
8. When using negative pressure on a supply plenum, where should the vacuum
source be attached?
A) To a remote return grille
B) To the outdoor condenser unit
C) As close as possible to the area being cleaned
, D) To the gas line for stability
ANSWER ✓ C) As close as possible to the area being cleaned
9. Which instrument is used to verify that negative pressure is maintained
throughout the cleaning process?
A) Thermometer
B) Anemometer
C) Manometer
D) Hygrometer
ANSWER ✓ C) Manometer
10. A "critical barrier" in containment refers to:
A) A plastic sheet over a doorway.
B) A sealed zipper entry and double-layer barrier.
C) A sign indicating a work zone.
D) A tarp placed over the floor.
ANSWER ✓ B) A sealed zipper entry and double-layer barrier.
Section 3: Inspection & Assessment
11. Prior to cleaning, what is the most important documentation step regarding
the system's condition?
A) Obtaining a signature from the homeowner.
B) Pre-existing damage documentation via photography/video.
C) Measuring the ambient temperature.
D) Calculating the system’s SEER rating.
ANSWER ✓ B) Pre-existing damage documentation via photography/video.
12. What type of contamination is typically black, greasy, and often found near
return grilles or kitchens?
A) Fiberglass particulate
B) Construction dust
C) Mold
D) PAG (Polyalkylene Glycol) oil residue
ANSWER ✓ D) PAG (Polyalkylene Glycol) oil residue
13. According to NADCA, what is the minimum level of access required to properly
clean a main supply duct?
Association) study guide based on the
updated 2026/2027 syllabus
ACR (Air Systems Cleaning Specialist) certification, including safety,
inspection, containment, methodologies, equipment, and industry standards
(NADCA 2026/2027).
Section 1: General Industry Knowledge & Standards
1. What is the primary standard that dictates the recommended practices for
HVAC system cleaning in the United States?
A) IICRC S500
B) ANSI/ACCA 4 QI
C) ANSI/ASHRAE Standard 62.1
D) NADCA ACR Standard
ANSWER ✓ D) NADCA ACR Standard
2. According to the updated 2026/2027 syllabus, what is the minimum required
negative pressure differential when connecting a containment device to an HVAC
system?
A) 0.05 inches of water column (in. w.c.)
B) 0.10 inches of water column (in. w.c.)
C) 0.25 inches of water column (in. w.c.)
D) 0.50 inches of water column (in. w.c.)
ANSWER ✓ A) 0.05 inches of water column (in. w.c.)
3. Which organization’s standards are primarily referenced by NADCA for safety
protocols regarding lockout/tagout?
A) EPA
B) OSHA
C) NFPA
D) ASTM
ANSWER ✓ B) OSHA
,4. What does the acronym "HVAC" stand for in the context of air systems
cleaning?
A) High Velocity Air Circulation
B) Heating, Ventilating, and Air Conditioning
C) Horizontal Vertical Air Control
D) High Volume Air Conveyance
ANSWER ✓ B) Heating, Ventilating, and Air Conditioning
5. The primary goal of a mechanical cleaning process in HVAC systems is to:
A) Disinfect the ductwork using chemical sprays.
B) Seal leaks in the ductwork to improve efficiency.
C) Dislodge and remove debris from the interior surfaces.
D) Increase the static pressure of the blower motor.
ANSWER ✓ C) Dislodge and remove debris from the interior surfaces.
Section 2: Containment & Negative Pressure
6. When performing cleaning on a multi-zone system, what is the critical
requirement regarding containment?
A) Only clean one zone per day.
B) Containment must be established on each zone individually.
C) The entire system must be cleaned simultaneously.
D) Only the main trunk line requires containment.
ANSWER ✓ B) Containment must be established on each zone individually.
7. What is the purpose of a "bubble" or "source" containment?
A) To prevent debris from exiting the HVAC equipment during cleaning.
B) To protect the surrounding furniture from cleaning tools.
C) To allow the technician to monitor airflow visually.
D) To increase the temperature inside the work area.
ANSWER ✓ A) To prevent debris from exiting the HVAC equipment during
cleaning.
8. When using negative pressure on a supply plenum, where should the vacuum
source be attached?
A) To a remote return grille
B) To the outdoor condenser unit
C) As close as possible to the area being cleaned
, D) To the gas line for stability
ANSWER ✓ C) As close as possible to the area being cleaned
9. Which instrument is used to verify that negative pressure is maintained
throughout the cleaning process?
A) Thermometer
B) Anemometer
C) Manometer
D) Hygrometer
ANSWER ✓ C) Manometer
10. A "critical barrier" in containment refers to:
A) A plastic sheet over a doorway.
B) A sealed zipper entry and double-layer barrier.
C) A sign indicating a work zone.
D) A tarp placed over the floor.
ANSWER ✓ B) A sealed zipper entry and double-layer barrier.
Section 3: Inspection & Assessment
11. Prior to cleaning, what is the most important documentation step regarding
the system's condition?
A) Obtaining a signature from the homeowner.
B) Pre-existing damage documentation via photography/video.
C) Measuring the ambient temperature.
D) Calculating the system’s SEER rating.
ANSWER ✓ B) Pre-existing damage documentation via photography/video.
12. What type of contamination is typically black, greasy, and often found near
return grilles or kitchens?
A) Fiberglass particulate
B) Construction dust
C) Mold
D) PAG (Polyalkylene Glycol) oil residue
ANSWER ✓ D) PAG (Polyalkylene Glycol) oil residue
13. According to NADCA, what is the minimum level of access required to properly
clean a main supply duct?
