NYC CUSTODIAN ENGINEER (BOE) PRACTICE
EXAM QUESTIONS AND CORRECT ANSWERS
PLUS RATIONALES 2026/2027 Q&A |
INSTANT DOWNLOAD PDF
Core Domains
Boiler Operations and Steam Systems
HVAC Systems and Refrigeration
Electrical Systems and Motor Maintenance
Plumbing Systems and Water Quality
Fire Safety and FDNY Regulations
Building Codes and Regulatory Compliance
Administrative Management and DOE Procedures
Introduction
The NYC Custodian Engineer (Board of Education) Exam evaluates a candidate's technical
competency and administrative judgment for operating and maintaining New York City
public school facilities. The exam assesses knowledge of boiler systems, HVAC, electrical
distribution, plumbing, fire safety, and NYC regulatory compliance. Candidates must
demonstrate critical thinking and decision-making under real-world conditions. The
multiple-choice format includes scenario-based questions emphasizing practical
troubleshooting, safety protocols, and sound professional judgment.
SECTION ONE: QUESTIONS 1–100
1. According to the New York City Mechanical Code, what is the maximum allowable
pressure for a boiler to be legally classified and operated as a "low-pressure" steam
boiler?
,A. 5 psi
B. 15 psi
C. 100 psi
D. 150 psi
🟢 Correct answer: B. 15 psi
🔴 RATIONALE: In NYC, any steam boiler operating above 15 psi is classified as high-
pressure and requires a different class of licensure and stricter operating protocols.
2. What is the primary function of the "Hartford Loop" in a steam heating system found
in many older New York City public school buildings?
A. To increase the velocity of steam as it travels to the furthest radiator
B. To provide a bypass route 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 before it reaches the boiler
🟢 Correct 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.
3. Which specific device is mandated by NYC code to shut off the fuel supply to the
burner if the water level in the boiler drops below the lowest safe operating point?
A. The pressuretrol
B. The aqua-stat
C. The low-water cutoff
D. The OS&Y valve
,🟢 Correct answer: C. The low-water cutoff
🔴 RATIONALE: The low-water cutoff is the most critical safety device on a boiler,
preventing a dry-fire condition which could lead to a catastrophic boiler explosion.
4. If a Custodian Engineer observes "priming" or "foaming" in the boiler sight glass,
which of the following is the most likely cause and appropriate corrective action?
A. Low water level; add more feedwater immediately
B. High concentration of dissolved solids or oil in the water; perform a surface
blowdown
C. Excessive oxygen in the system; add sodium sulfite
D. Scale buildup on the tubes; increase the dosage of phosphates
🟢 Correct answer: B. High concentration of dissolved solids or oil in the water; perform
a surface blowdown
🔴 RATIONALE: Foaming is caused by impurities on the surface of the water; a surface
blowdown removes these impurities to prevent water carryover into the steam lines.
5. In a centrifugal pump used for chilled water circulation, what is the purpose of the
"wear rings"?
A. To provide a seal that prevents water from leaking out of the pump shaft
B. To provide a replaceable surface that maintains internal efficiency by minimizing
leakage between the discharge and suction sides
C. To hold the impeller in place on the pump shaft
D. To lubricate the bearings during high-speed operation
🟢 Correct answer: B. To provide a replaceable surface that maintains internal efficiency
by minimizing leakage between the discharge and suction sides
🔴 RATIONALE: Wear rings allow the pump to maintain high pressure by sealing the
gap between the rotating impeller and the stationary housing; they are designed to be
replaced as they wear down.
, 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. Attempt to locate the leak using a soapy water solution
🟢 Correct answer: C. Evacuate the area and call 911 from a remote location
🔴 RATIONALE: Any action that could create a spark—including using a phone in the
area or operating electrical switches—poses an ignition risk. Evacuation and calling from
a safe remote location is the mandated first step per FDNY safety protocols.
7. What is the primary purpose of a boiler's safety valve?
A. To control the water temperature
B. To automatically release excess pressure and prevent boiler explosions
C. To regulate the fuel flow to the burner
D. To monitor the water level in the boiler
🟢 Correct answer: B. To automatically release excess pressure and prevent boiler
explosions
🔴 RATIONALE: Safety valves are critical pressure-relief devices that automatically open
when the boiler pressure exceeds the set point, preventing catastrophic boiler failure.
8. 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
EXAM QUESTIONS AND CORRECT ANSWERS
PLUS RATIONALES 2026/2027 Q&A |
INSTANT DOWNLOAD PDF
Core Domains
Boiler Operations and Steam Systems
HVAC Systems and Refrigeration
Electrical Systems and Motor Maintenance
Plumbing Systems and Water Quality
Fire Safety and FDNY Regulations
Building Codes and Regulatory Compliance
Administrative Management and DOE Procedures
Introduction
The NYC Custodian Engineer (Board of Education) Exam evaluates a candidate's technical
competency and administrative judgment for operating and maintaining New York City
public school facilities. The exam assesses knowledge of boiler systems, HVAC, electrical
distribution, plumbing, fire safety, and NYC regulatory compliance. Candidates must
demonstrate critical thinking and decision-making under real-world conditions. The
multiple-choice format includes scenario-based questions emphasizing practical
troubleshooting, safety protocols, and sound professional judgment.
SECTION ONE: QUESTIONS 1–100
1. According to the New York City Mechanical Code, what is the maximum allowable
pressure for a boiler to be legally classified and operated as a "low-pressure" steam
boiler?
,A. 5 psi
B. 15 psi
C. 100 psi
D. 150 psi
🟢 Correct answer: B. 15 psi
🔴 RATIONALE: In NYC, any steam boiler operating above 15 psi is classified as high-
pressure and requires a different class of licensure and stricter operating protocols.
2. What is the primary function of the "Hartford Loop" in a steam heating system found
in many older New York City public school buildings?
A. To increase the velocity of steam as it travels to the furthest radiator
B. To provide a bypass route 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 before it reaches the boiler
🟢 Correct 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.
3. Which specific device is mandated by NYC code to shut off the fuel supply to the
burner if the water level in the boiler drops below the lowest safe operating point?
A. The pressuretrol
B. The aqua-stat
C. The low-water cutoff
D. The OS&Y valve
,🟢 Correct answer: C. The low-water cutoff
🔴 RATIONALE: The low-water cutoff is the most critical safety device on a boiler,
preventing a dry-fire condition which could lead to a catastrophic boiler explosion.
4. If a Custodian Engineer observes "priming" or "foaming" in the boiler sight glass,
which of the following is the most likely cause and appropriate corrective action?
A. Low water level; add more feedwater immediately
B. High concentration of dissolved solids or oil in the water; perform a surface
blowdown
C. Excessive oxygen in the system; add sodium sulfite
D. Scale buildup on the tubes; increase the dosage of phosphates
🟢 Correct answer: B. High concentration of dissolved solids or oil in the water; perform
a surface blowdown
🔴 RATIONALE: Foaming is caused by impurities on the surface of the water; a surface
blowdown removes these impurities to prevent water carryover into the steam lines.
5. In a centrifugal pump used for chilled water circulation, what is the purpose of the
"wear rings"?
A. To provide a seal that prevents water from leaking out of the pump shaft
B. To provide a replaceable surface that maintains internal efficiency by minimizing
leakage between the discharge and suction sides
C. To hold the impeller in place on the pump shaft
D. To lubricate the bearings during high-speed operation
🟢 Correct answer: B. To provide a replaceable surface that maintains internal efficiency
by minimizing leakage between the discharge and suction sides
🔴 RATIONALE: Wear rings allow the pump to maintain high pressure by sealing the
gap between the rotating impeller and the stationary housing; they are designed to be
replaced as they wear down.
, 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. Attempt to locate the leak using a soapy water solution
🟢 Correct answer: C. Evacuate the area and call 911 from a remote location
🔴 RATIONALE: Any action that could create a spark—including using a phone in the
area or operating electrical switches—poses an ignition risk. Evacuation and calling from
a safe remote location is the mandated first step per FDNY safety protocols.
7. What is the primary purpose of a boiler's safety valve?
A. To control the water temperature
B. To automatically release excess pressure and prevent boiler explosions
C. To regulate the fuel flow to the burner
D. To monitor the water level in the boiler
🟢 Correct answer: B. To automatically release excess pressure and prevent boiler
explosions
🔴 RATIONALE: Safety valves are critical pressure-relief devices that automatically open
when the boiler pressure exceeds the set point, preventing catastrophic boiler failure.
8. 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
