NYC Custodian Engineer Exam Practice Test
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
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CORE DOMAINS COVERED IN THIS EXAM
1. Boiler Operations & Steam Systems (High & Low Pressure) - Boiler
types, safety devices, water treatment, Hartford Loop, pressure controls,
burner operation, blowdown procedures
2. Heating, Ventilation, and Air Conditioning (HVAC) Systems - Air
handling units, chillers, cooling towers, thermostats, air filters, refrigeration
cycle, system troubleshooting
3. Fire Safety & FDNY Regulations - Fire extinguisher classifications and
inspection, smoke control systems, FDNY Certificates of Fitness (P-99, S-
95, F-03), fire alarm systems, sprinkler systems
4. Electrical Systems & Safety - Lockout/Tagout procedures, electrical
panels, wiring, motors, voltage measurement, electrical safety protocols
5. Plumbing Systems & Water Quality - Piping systems, pumps
(centrifugal), valves, water treatment, backflow prevention, leak detection
6. Preventive Maintenance & Equipment Inspection - Maintenance
scheduling, equipment logs, inspection procedures, condition-based
maintenance
7. Building Operations & Facility Management - Energy conservation,
environmental compliance, building codes, administrative duties, record
keeping
8. Safety & Environmental Compliance - OSHA standards, hazardous
materials handling, confined space safety, PPE, carbon monoxide detection,
emergency response
9. NYC Building Codes & Regulatory Standards - NYC Mechanical Code,
NYC Building Code, NYC Fire Code, ASME Boiler Code, Local Law 97
,1. What is the primary responsibility of a custodian engineer in a NYC public
building?
A. Designing building blueprints
B. Supervising construction crews
C. Maintaining and operating building systems
D. Conducting fire inspections only
ANSWER: C. Maintaining and operating building systems
RATIONALE: Custodian engineers are responsible for the operation and
maintenance of mechanical, electrical, and plumbing systems in buildings. They
oversee the overall operation, maintenance, and safety of school facilities and
mechanical systems.
2. According to the NYC Mechanical Code, what is the maximum allowable
pressure for a low-pressure steam boiler?
A. 5 psi
B. 15 psi
C. 100 psi
D. 150 psi
ANSWER: B. 15 psi
RATIONALE: Low-pressure steam boilers are limited to 15 psig. Any boiler
operating above 15 psi is classified as high-pressure and requires a different class
of licensure and stricter operating protocols.
3. Which fuel is most commonly used in NYC public building boiler systems?
A. Gasoline
B. Natural gas
C. Diesel
D. Propane
ANSWER: B. Natural gas
, RATIONALE: Natural gas is widely used for boilers due to its efficiency,
availability, and cost-effectiveness. Many NYC school boilers have dual-fuel
capability.
4. Which safety device prevents a boiler from exceeding its maximum
pressure?
A. Thermostat
B. Pressure relief valve
C. Water level gauge
D. Feedwater pump
ANSWER: B. Pressure relief valve
RATIONALE: Pressure relief valves automatically release excess pressure to
prevent boiler explosions. Safety valves automatically release pressure to prevent
boiler explosions.
5. What is the primary function of the Hartford Loop in a steam heating
system?
A. To increase steam velocity to radiators
B. To provide a bypass for steam when the main header is closed
C. To prevent the boiler from losing its water level below a safe point in the event
of a leak in the return line
D. To trap air and vent it out of the system
ANSWER: C. To prevent the boiler from losing its water level below a
safe point in the event of a leak in the return line
RATIONALE: The Hartford Loop is a safety piping arrangement that
prevents water from being siphoned out of the boiler if a return line breaks,
protecting the crown sheet from overheating.
6. A custodian engineer notices a faint odor of natural gas in a school boiler
room. What is the FIRST course of action?
, A. Locate the main gas shut-off valve and close it
B. Open all windows and doors to ventilate the area
C. Evacuate the area and call 911 from a remote location
D. Investigate the source of the leak
ANSWER: C. Evacuate the area and call 911 from a remote location
RATIONALE: Safety is paramount. The first action when smelling gas is to
evacuate the area and call 911 from a safe remote location. Do not use phones,
switches, or create sparks in the area.
7. A custodian engineer discovers that a low-pressure boiler is short-cycling
repeatedly during peak heating hours. What is the MOST appropriate first
action?
A. Replace the circulating pump immediately
B. Increase the thermostat setting throughout the building
C. Inspect the pressure control and operating controls
D. Shut down the boiler for the remainder of the day
ANSWER: C. Inspect the pressure control and operating controls
RATIONALE: Short-cycling is commonly caused by faulty pressure controls
or operating controls. The engineer should inspect these components first before
taking more drastic measures.
8. What is the purpose of a boiler blowdown?
A. Clean burner nozzles
B. Reduce fuel usage
C. Remove sediment and impurities
D. Increase steam production
ANSWER: C. Remove sediment and impurities
RATIONALE: Blowdown removes sludge and dissolved solids that
accumulate in the boiler. Regular blowdown is essential for maintaining boiler
efficiency and preventing scale buildup.
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download PDF
CORE DOMAINS COVERED IN THIS EXAM
1. Boiler Operations & Steam Systems (High & Low Pressure) - Boiler
types, safety devices, water treatment, Hartford Loop, pressure controls,
burner operation, blowdown procedures
2. Heating, Ventilation, and Air Conditioning (HVAC) Systems - Air
handling units, chillers, cooling towers, thermostats, air filters, refrigeration
cycle, system troubleshooting
3. Fire Safety & FDNY Regulations - Fire extinguisher classifications and
inspection, smoke control systems, FDNY Certificates of Fitness (P-99, S-
95, F-03), fire alarm systems, sprinkler systems
4. Electrical Systems & Safety - Lockout/Tagout procedures, electrical
panels, wiring, motors, voltage measurement, electrical safety protocols
5. Plumbing Systems & Water Quality - Piping systems, pumps
(centrifugal), valves, water treatment, backflow prevention, leak detection
6. Preventive Maintenance & Equipment Inspection - Maintenance
scheduling, equipment logs, inspection procedures, condition-based
maintenance
7. Building Operations & Facility Management - Energy conservation,
environmental compliance, building codes, administrative duties, record
keeping
8. Safety & Environmental Compliance - OSHA standards, hazardous
materials handling, confined space safety, PPE, carbon monoxide detection,
emergency response
9. NYC Building Codes & Regulatory Standards - NYC Mechanical Code,
NYC Building Code, NYC Fire Code, ASME Boiler Code, Local Law 97
,1. What is the primary responsibility of a custodian engineer in a NYC public
building?
A. Designing building blueprints
B. Supervising construction crews
C. Maintaining and operating building systems
D. Conducting fire inspections only
ANSWER: C. Maintaining and operating building systems
RATIONALE: Custodian engineers are responsible for the operation and
maintenance of mechanical, electrical, and plumbing systems in buildings. They
oversee the overall operation, maintenance, and safety of school facilities and
mechanical systems.
2. According to the NYC Mechanical Code, what is the maximum allowable
pressure for a low-pressure steam boiler?
A. 5 psi
B. 15 psi
C. 100 psi
D. 150 psi
ANSWER: B. 15 psi
RATIONALE: Low-pressure steam boilers are limited to 15 psig. Any boiler
operating above 15 psi is classified as high-pressure and requires a different class
of licensure and stricter operating protocols.
3. Which fuel is most commonly used in NYC public building boiler systems?
A. Gasoline
B. Natural gas
C. Diesel
D. Propane
ANSWER: B. Natural gas
, RATIONALE: Natural gas is widely used for boilers due to its efficiency,
availability, and cost-effectiveness. Many NYC school boilers have dual-fuel
capability.
4. Which safety device prevents a boiler from exceeding its maximum
pressure?
A. Thermostat
B. Pressure relief valve
C. Water level gauge
D. Feedwater pump
ANSWER: B. Pressure relief valve
RATIONALE: Pressure relief valves automatically release excess pressure to
prevent boiler explosions. Safety valves automatically release pressure to prevent
boiler explosions.
5. What is the primary function of the Hartford Loop in a steam heating
system?
A. To increase steam velocity to radiators
B. To provide a bypass for steam when the main header is closed
C. To prevent the boiler from losing its water level below a safe point in the event
of a leak in the return line
D. To trap air and vent it out of the system
ANSWER: C. To prevent the boiler from losing its water level below a
safe point in the event of a leak in the return line
RATIONALE: The Hartford Loop is a safety piping arrangement that
prevents water from being siphoned out of the boiler if a return line breaks,
protecting the crown sheet from overheating.
6. A custodian engineer notices a faint odor of natural gas in a school boiler
room. What is the FIRST course of action?
, A. Locate the main gas shut-off valve and close it
B. Open all windows and doors to ventilate the area
C. Evacuate the area and call 911 from a remote location
D. Investigate the source of the leak
ANSWER: C. Evacuate the area and call 911 from a remote location
RATIONALE: Safety is paramount. The first action when smelling gas is to
evacuate the area and call 911 from a safe remote location. Do not use phones,
switches, or create sparks in the area.
7. A custodian engineer discovers that a low-pressure boiler is short-cycling
repeatedly during peak heating hours. What is the MOST appropriate first
action?
A. Replace the circulating pump immediately
B. Increase the thermostat setting throughout the building
C. Inspect the pressure control and operating controls
D. Shut down the boiler for the remainder of the day
ANSWER: C. Inspect the pressure control and operating controls
RATIONALE: Short-cycling is commonly caused by faulty pressure controls
or operating controls. The engineer should inspect these components first before
taking more drastic measures.
8. What is the purpose of a boiler blowdown?
A. Clean burner nozzles
B. Reduce fuel usage
C. Remove sediment and impurities
D. Increase steam production
ANSWER: C. Remove sediment and impurities
RATIONALE: Blowdown removes sludge and dissolved solids that
accumulate in the boiler. Regular blowdown is essential for maintaining boiler
efficiency and preventing scale buildup.
