NYC CUSTODIAN ENGINEER FINAL
EXAM QUESTIONS AND ANSWERS
2026/2027
1. Under the NYC Boiler Code, what is the maximum allowable working pressure (MAWP) for
a low-pressure steam boiler?
A. 15 psi
B. 10 psi
C. 5 psi
D. 30 psi
Answer: A
Conceptual Explanation: A low-pressure steam boiler is defined by the ASME and NYC
code as one operating at a pressure not exceeding 15 psi.
2. Which device is specifically designed to protect a steam boiler from a dry-fire condition by
shutting off the fuel supply?
A. Low Water Cut-Off (LWCO)
B. Pressuretrol
,C. Aquastat
D. Safety Valve
Answer: A
Conceptual Explanation: The LWCO monitors water levels and interrupts the burner
circuit if the level drops below a safe minimum, preventing a dry-fire.
3. In a two-pipe vacuum steam system, what is the primary function of the thermostatic
radiator trap?
A. To regulate the flow of air into the radiator
B. To increase the boiler pressure
C. To prevent steam from entering the return line
D. To act as a secondary safety relief
Answer: C
Conceptual Explanation: Thermostatic traps allow air and condensate to exit the radiator
but close when they sense steam, preventing steam from entering the dry return lines.
4. What is the result of ‘foaming’ in a steam boiler, and how is it primarily detected?
A. Rapidly rising pressure; detected by the gauge
B. Excessive fuel consumption; detected by the meter
C. Scale buildup; detected by annual inspection
, D. Carryover of water into steam lines; detected by a fluctuating sight glass
Answer: D
Conceptual Explanation: Foaming is caused by high concentrations of dissolved solids or
oil, resulting in erratic water levels visible in the gauge glass.
5. A ‘Hartford Loop’ is installed in steam boiler piping to prevent what occurrence?
A. Excessive pressure buildup
B. Water hammer in the mains
C. Water from leaving the boiler in case of a return line leak
D. Oxygen corrosion in the header
Answer: C
Conceptual Explanation: The Hartford Loop uses pressure balancing to ensure water
cannot be forced out of the boiler below a safe level if a leak occurs in the return piping.
6. What is the NYC Local Law 87 requirement concerning large buildings?
A. Energy audits and retro-commissioning every 10 years
B. Annual boiler inspections by a licensed plumber
C. Mandatory installation of low-flow toilets
D. Monthly asbestos reporting
Answer: A
EXAM QUESTIONS AND ANSWERS
2026/2027
1. Under the NYC Boiler Code, what is the maximum allowable working pressure (MAWP) for
a low-pressure steam boiler?
A. 15 psi
B. 10 psi
C. 5 psi
D. 30 psi
Answer: A
Conceptual Explanation: A low-pressure steam boiler is defined by the ASME and NYC
code as one operating at a pressure not exceeding 15 psi.
2. Which device is specifically designed to protect a steam boiler from a dry-fire condition by
shutting off the fuel supply?
A. Low Water Cut-Off (LWCO)
B. Pressuretrol
,C. Aquastat
D. Safety Valve
Answer: A
Conceptual Explanation: The LWCO monitors water levels and interrupts the burner
circuit if the level drops below a safe minimum, preventing a dry-fire.
3. In a two-pipe vacuum steam system, what is the primary function of the thermostatic
radiator trap?
A. To regulate the flow of air into the radiator
B. To increase the boiler pressure
C. To prevent steam from entering the return line
D. To act as a secondary safety relief
Answer: C
Conceptual Explanation: Thermostatic traps allow air and condensate to exit the radiator
but close when they sense steam, preventing steam from entering the dry return lines.
4. What is the result of ‘foaming’ in a steam boiler, and how is it primarily detected?
A. Rapidly rising pressure; detected by the gauge
B. Excessive fuel consumption; detected by the meter
C. Scale buildup; detected by annual inspection
, D. Carryover of water into steam lines; detected by a fluctuating sight glass
Answer: D
Conceptual Explanation: Foaming is caused by high concentrations of dissolved solids or
oil, resulting in erratic water levels visible in the gauge glass.
5. A ‘Hartford Loop’ is installed in steam boiler piping to prevent what occurrence?
A. Excessive pressure buildup
B. Water hammer in the mains
C. Water from leaving the boiler in case of a return line leak
D. Oxygen corrosion in the header
Answer: C
Conceptual Explanation: The Hartford Loop uses pressure balancing to ensure water
cannot be forced out of the boiler below a safe level if a leak occurs in the return piping.
6. What is the NYC Local Law 87 requirement concerning large buildings?
A. Energy audits and retro-commissioning every 10 years
B. Annual boiler inspections by a licensed plumber
C. Mandatory installation of low-flow toilets
D. Monthly asbestos reporting
Answer: A
