NYC Custodian Engineer Exam Prep:
Ultimate 2026/2027 Newest Test Bank &
Practice Questions
What is the primary purpose of a boiler safety valve?
A. Increase boiler pressure
B. Regulate feedwater temperature
C. Relieve excessive pressure
D. Increase combustion efficiency
Answer: C. Relieve excessive pressure
Rationale: A safety valve opens automatically when pressure reaches its set point,
preventing dangerous overpressure.
A boiler's pressure gauge primarily indicates:
A. Water level
B. Fuel consumption
C. System pressure
D. Flue-gas temperature
Answer: C. System pressure
Rationale: The pressure gauge provides the operator with the boiler or system
pressure and helps identify abnormal operating conditions.
What is the purpose of a low-water cutoff?
A. Increase steam production
B. Control fuel quality
C. Prevent operation when boiler water is dangerously low
D. Increase feedwater pressure
Answer: C. Prevent operation when boiler water is dangerously low
,Rationale: Low water can expose heating surfaces and cause severe overheating
or boiler damage.
Before servicing energized electrical equipment, the safest general procedure is to:
A. Increase the voltage
B. Remove only the fuse
C. De-energize and apply appropriate lockout/tagout procedures
D. Spray the equipment with water
Answer: C. De-energize and apply appropriate lockout/tagout procedures
Rationale: Lockout/tagout helps prevent unexpected energization while
maintenance is being performed.
What does HVAC stand for?
A. Heating Valve and Air Control
B. Heating, Ventilation, and Air Conditioning
C. Heat Vapor and Cooling
D. Heating Vacuum and Circulation
Answer: B. Heating, Ventilation, and Air Conditioning
Rationale: HVAC describes systems used to control temperature, air movement,
ventilation, and often humidity.
What is the main function of a thermostat?
A. Increase electrical resistance
B. Measure water pressure
C. Sense temperature and control equipment operation
D. Remove sediment from boilers
Answer: C. Sense temperature and control equipment operation
Rationale: A thermostat responds to temperature and signals heating or cooling
equipment to operate as needed.
What is the principal purpose of preventive maintenance?
,A. Wait for equipment failure
B. Eliminate all inspections
C. Reduce failures and extend equipment service life
D. Increase emergency repairs
Answer: C. Reduce failures and extend equipment service life
Rationale: Preventive maintenance identifies wear and developing problems
before they result in major failures.
A boiler blowdown is primarily used to:
A. Add fuel
B. Increase burner pressure
C. Remove concentrated dissolved solids and sediment
D. Increase room temperature
Answer: C. Remove concentrated dissolved solids and sediment
Rationale: Blowdown controls boiler-water concentration and removes
accumulated impurities.
What does a sight glass on a boiler commonly indicate?
A. Fuel pressure
B. Steam temperature
C. Water level
D. Motor speed
Answer: C. Water level
Rationale: The sight glass allows the operator to visually monitor the boiler water
level.
If the water level in a steam boiler is dangerously low, the operator should first:
A. Increase the firing rate
B. Disable the safety valve
C. Follow the emergency operating procedure and shut down firing as
required
D. Open every steam valve
, Answer: C. Follow the emergency operating procedure and shut down firing as
required
Rationale: Continuing to fire a boiler with inadequate water can severely damage
heating surfaces and create a dangerous condition.
What is the purpose of a boiler burner?
A. Remove condensate
B. Provide controlled combustion to produce heat
C. Measure steam pressure
D. Reduce water hardness
Answer: B. Provide controlled combustion to produce heat
Rationale: The burner mixes fuel and air and produces controlled combustion that
transfers heat to the boiler.
Incomplete combustion can produce excessive:
A. Oxygen
B. Water hardness
C. Carbon monoxide
D. Condensate
Answer: C. Carbon monoxide
Rationale: Inadequate oxygen or improper combustion conditions can increase
carbon monoxide production.
A blue flame in a properly adjusted gas burner generally indicates:
A. No combustion
B. Relatively complete combustion
C. Excessive water hardness
D. Boiler flooding
Answer: B. Relatively complete combustion
Ultimate 2026/2027 Newest Test Bank &
Practice Questions
What is the primary purpose of a boiler safety valve?
A. Increase boiler pressure
B. Regulate feedwater temperature
C. Relieve excessive pressure
D. Increase combustion efficiency
Answer: C. Relieve excessive pressure
Rationale: A safety valve opens automatically when pressure reaches its set point,
preventing dangerous overpressure.
A boiler's pressure gauge primarily indicates:
A. Water level
B. Fuel consumption
C. System pressure
D. Flue-gas temperature
Answer: C. System pressure
Rationale: The pressure gauge provides the operator with the boiler or system
pressure and helps identify abnormal operating conditions.
What is the purpose of a low-water cutoff?
A. Increase steam production
B. Control fuel quality
C. Prevent operation when boiler water is dangerously low
D. Increase feedwater pressure
Answer: C. Prevent operation when boiler water is dangerously low
,Rationale: Low water can expose heating surfaces and cause severe overheating
or boiler damage.
Before servicing energized electrical equipment, the safest general procedure is to:
A. Increase the voltage
B. Remove only the fuse
C. De-energize and apply appropriate lockout/tagout procedures
D. Spray the equipment with water
Answer: C. De-energize and apply appropriate lockout/tagout procedures
Rationale: Lockout/tagout helps prevent unexpected energization while
maintenance is being performed.
What does HVAC stand for?
A. Heating Valve and Air Control
B. Heating, Ventilation, and Air Conditioning
C. Heat Vapor and Cooling
D. Heating Vacuum and Circulation
Answer: B. Heating, Ventilation, and Air Conditioning
Rationale: HVAC describes systems used to control temperature, air movement,
ventilation, and often humidity.
What is the main function of a thermostat?
A. Increase electrical resistance
B. Measure water pressure
C. Sense temperature and control equipment operation
D. Remove sediment from boilers
Answer: C. Sense temperature and control equipment operation
Rationale: A thermostat responds to temperature and signals heating or cooling
equipment to operate as needed.
What is the principal purpose of preventive maintenance?
,A. Wait for equipment failure
B. Eliminate all inspections
C. Reduce failures and extend equipment service life
D. Increase emergency repairs
Answer: C. Reduce failures and extend equipment service life
Rationale: Preventive maintenance identifies wear and developing problems
before they result in major failures.
A boiler blowdown is primarily used to:
A. Add fuel
B. Increase burner pressure
C. Remove concentrated dissolved solids and sediment
D. Increase room temperature
Answer: C. Remove concentrated dissolved solids and sediment
Rationale: Blowdown controls boiler-water concentration and removes
accumulated impurities.
What does a sight glass on a boiler commonly indicate?
A. Fuel pressure
B. Steam temperature
C. Water level
D. Motor speed
Answer: C. Water level
Rationale: The sight glass allows the operator to visually monitor the boiler water
level.
If the water level in a steam boiler is dangerously low, the operator should first:
A. Increase the firing rate
B. Disable the safety valve
C. Follow the emergency operating procedure and shut down firing as
required
D. Open every steam valve
, Answer: C. Follow the emergency operating procedure and shut down firing as
required
Rationale: Continuing to fire a boiler with inadequate water can severely damage
heating surfaces and create a dangerous condition.
What is the purpose of a boiler burner?
A. Remove condensate
B. Provide controlled combustion to produce heat
C. Measure steam pressure
D. Reduce water hardness
Answer: B. Provide controlled combustion to produce heat
Rationale: The burner mixes fuel and air and produces controlled combustion that
transfers heat to the boiler.
Incomplete combustion can produce excessive:
A. Oxygen
B. Water hardness
C. Carbon monoxide
D. Condensate
Answer: C. Carbon monoxide
Rationale: Inadequate oxygen or improper combustion conditions can increase
carbon monoxide production.
A blue flame in a properly adjusted gas burner generally indicates:
A. No combustion
B. Relatively complete combustion
C. Excessive water hardness
D. Boiler flooding
Answer: B. Relatively complete combustion
