NYC CUSTODIAN ENGINEER EXAM
COMPLETE 300 QUESTIONS WITH
DETAILED VERIFIED ANSWERS (100%
CORRECT ANSWERS /ALREADY
GRADED A+
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
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.
Low-pressure steam boilers are limited to 15 psig (pounds per square inch gauge).
High-pressure boilers operate above 15 psig.
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.
1
,D. To trap air and vent it out of the system before it reaches the boiler.
Correct Answer: C
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. If a Custodian Engineer observes "priming" or "foaming" in the boiler sight
glass, which of the following is the most likely cause and appropriate chemical
treatment?
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
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. Blowdown removes impurities that settle at the bottom of the boiler,
preventing scale buildup and maintaining water quality.
4. 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
2
,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.
If water level drops too low, the boiler tubes can overheat, warp, or rupture. The
LWCO breaks the electrical circuit to the burner, shutting off the fuel supply.
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
Rationale: Wear rings provide a replaceable surface that maintains internal
efficiency by minimizing leakage between the discharge and suction sides of the
pump.
6. Which NYC agency primarily enforces the Building Code and issues permits for
boiler installations?
A. FDNY
B. NYS Department of Labor
C. NYC Department of Buildings (DOB)
D. NYC Department of Environmental Protection
Correct Answer: C
Rationale: The NYC Department of Buildings (DOB) oversees construction,
alteration, and maintenance of buildings, including boiler installations and permits.
7. A custodian engineer finds a minor gas leak near a boiler. The first action should
be:
3
, A. Call a licensed plumber
B. Shut off the gas supply and ventilate the area
C. Ignite a pilot light to burn off the gas
D. Notify the principal immediately
Correct Answer: B
Rationale: Safety protocols require immediately stopping the gas flow and
ventilating to prevent accumulation of flammable gas before any other actions.
8. What is the primary purpose of a "blowdown" on a steam boiler?
A. To reduce steam pressure
B. To remove sediment and dissolved solids from the boiler water
C. To test the safety valve
D. To increase boiler efficiency by lowering water temperature
Correct Answer: B
Rationale: Blowdown removes impurities that settle at the bottom of the boiler,
preventing scale buildup and maintaining water quality.
9. Under NYC Fire Code, how often must fire extinguishers be inspected?
A. Monthly
B. Quarterly
C. Annually
D. Every 5 years
Correct Answer: A
Rationale: NYC Fire Code requires portable fire extinguishers to be inspected
monthly and undergo annual maintenance.
4
COMPLETE 300 QUESTIONS WITH
DETAILED VERIFIED ANSWERS (100%
CORRECT ANSWERS /ALREADY
GRADED A+
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
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.
Low-pressure steam boilers are limited to 15 psig (pounds per square inch gauge).
High-pressure boilers operate above 15 psig.
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.
1
,D. To trap air and vent it out of the system before it reaches the boiler.
Correct Answer: C
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. If a Custodian Engineer observes "priming" or "foaming" in the boiler sight
glass, which of the following is the most likely cause and appropriate chemical
treatment?
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
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. Blowdown removes impurities that settle at the bottom of the boiler,
preventing scale buildup and maintaining water quality.
4. 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
2
,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.
If water level drops too low, the boiler tubes can overheat, warp, or rupture. The
LWCO breaks the electrical circuit to the burner, shutting off the fuel supply.
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
Rationale: Wear rings provide a replaceable surface that maintains internal
efficiency by minimizing leakage between the discharge and suction sides of the
pump.
6. Which NYC agency primarily enforces the Building Code and issues permits for
boiler installations?
A. FDNY
B. NYS Department of Labor
C. NYC Department of Buildings (DOB)
D. NYC Department of Environmental Protection
Correct Answer: C
Rationale: The NYC Department of Buildings (DOB) oversees construction,
alteration, and maintenance of buildings, including boiler installations and permits.
7. A custodian engineer finds a minor gas leak near a boiler. The first action should
be:
3
, A. Call a licensed plumber
B. Shut off the gas supply and ventilate the area
C. Ignite a pilot light to burn off the gas
D. Notify the principal immediately
Correct Answer: B
Rationale: Safety protocols require immediately stopping the gas flow and
ventilating to prevent accumulation of flammable gas before any other actions.
8. What is the primary purpose of a "blowdown" on a steam boiler?
A. To reduce steam pressure
B. To remove sediment and dissolved solids from the boiler water
C. To test the safety valve
D. To increase boiler efficiency by lowering water temperature
Correct Answer: B
Rationale: Blowdown removes impurities that settle at the bottom of the boiler,
preventing scale buildup and maintaining water quality.
9. Under NYC Fire Code, how often must fire extinguishers be inspected?
A. Monthly
B. Quarterly
C. Annually
D. Every 5 years
Correct Answer: A
Rationale: NYC Fire Code requires portable fire extinguishers to be inspected
monthly and undergo annual maintenance.
4
