NYC Custodian Engineer Practice Exam | Safety, Codes, HVAC, Plumbing & Maintenance | 2026-2027
What is the most important steam-boiler safety principle? Maintaining proper water level.
What should an operator do if no water is visible in the Shut the burner down and determine true water level.
gauge glass of a steam boiler?
What is the purpose of the low-water cutoff (LWCO)? To shut off fuel when water falls below a safe level.
What can cause a float-type LWCO to fail? Sludge or scale in the chamber.
What does the gauge glass show in a boiler? The water level.
What does blowing down the water column help confirm? That the level passages are open and accurate.
What controls the operating pressure on a steam boiler? Pressure control.
What controls the operating temperature on a hot-water Aquastat.
boiler?
What does the safety valve protect the boiler from? Overpressure.
What should a safety valve never be? Plugged or isolated in service.
What can scale buildup in an LWCO chamber cause? False level sensing.
What is the main purpose of the feedwater system? To maintain a safe boiler water level.
How does a steam boiler differ from a hot-water boiler? It produces steam for distribution.
What should not be done if a nuisance trip occurs on an Bypassed as a normal response.
LWCO?
What can poor heat transfer in a boiler result from? Scale and sediment buildup.
, NYC Custodian Engineer Practice Exam | Safety, Codes, HVAC, Plumbing & Maintenance | 2026-2027
What indicates frequent lifting of a safety valve? Another problem such as control failure or overfiring.
What is a danger of a clogged gauge glass connection? It may show a false normal water level.
What is the best answer regarding the safety valve? It should never be plugged or isolated in service.
What does the water column connect in a boiler? The boiler to the gauge glass and low-water controls.
What is the difference between a pressure control used for The pressure control is used for normal cycling.
normal cycling and a safety high-limit device?
What is a common cause of scale buildup in an LWCO Sludge accumulation.
chamber?
What is the first action if no water is visible in the gauge Shut the burner down and determine true water level.
glass?
What is the purpose of bottom blowdown? To remove sediment from low points.
What is a common misconception about steam boilers? That they never need controls.
What should be done if a safety valve is frequently lifting? Investigate for control failure or overfiring.
What does the safety valve protect against? Overpressure in the boiler.
What is the main purpose of a safety valve? To prevent boiler overpressure.
What is the burner flame? The flame produced by the burner in a boiler, used to heat water and generate
steam.
What is the condensate tank? A tank that collects condensate, which is the water formed when steam cools and
condenses.
What is the feedwater line? A pipe that delivers water to the boiler for steam generation.
, NYC Custodian Engineer Practice Exam | Safety, Codes, HVAC, Plumbing & Maintenance | 2026-2027
What is the safety high-limit device? A safety mechanism that shuts down the boiler if the temperature exceeds a preset
limit.
What is a pressure control used for normal cycling? It is different from the safety high-limit device.
What does blowing down the water column confirm? The level passages are open and accurate.
What connects the boiler to the gauge glass? The water column.
What is the main purpose of a fuse? To protect a circuit by melting open during overcurrent.
What should you do if a breaker keeps tripping? Find and correct the cause.
What does grounding mainly help with? Stabilizing the system and reducing shock hazards.
What does bonding connect metal parts together for? So that fault current can clear safely.
What is a GFCI primarily intended to protect against? Ground-fault shock hazards.
What should exit signs do? Remain illuminated and maintained.
What is a relay best described as? An electrically operated switch.
What can overcurrent result from? An overload or a short circuit/fault.
What is the main purpose of a circuit breaker? To open the circuit during unsafe current.
What are signs of a bad switch or outlet? Flickering, buzzing, and a burning smell.
What should you think about if many fixtures in one area An upstream circuit or control issue.
are out?
What is the most important steam-boiler safety principle? Maintaining proper water level.
What should an operator do if no water is visible in the Shut the burner down and determine true water level.
gauge glass of a steam boiler?
What is the purpose of the low-water cutoff (LWCO)? To shut off fuel when water falls below a safe level.
What can cause a float-type LWCO to fail? Sludge or scale in the chamber.
What does the gauge glass show in a boiler? The water level.
What does blowing down the water column help confirm? That the level passages are open and accurate.
What controls the operating pressure on a steam boiler? Pressure control.
What controls the operating temperature on a hot-water Aquastat.
boiler?
What does the safety valve protect the boiler from? Overpressure.
What should a safety valve never be? Plugged or isolated in service.
What can scale buildup in an LWCO chamber cause? False level sensing.
What is the main purpose of the feedwater system? To maintain a safe boiler water level.
How does a steam boiler differ from a hot-water boiler? It produces steam for distribution.
What should not be done if a nuisance trip occurs on an Bypassed as a normal response.
LWCO?
What can poor heat transfer in a boiler result from? Scale and sediment buildup.
, NYC Custodian Engineer Practice Exam | Safety, Codes, HVAC, Plumbing & Maintenance | 2026-2027
What indicates frequent lifting of a safety valve? Another problem such as control failure or overfiring.
What is a danger of a clogged gauge glass connection? It may show a false normal water level.
What is the best answer regarding the safety valve? It should never be plugged or isolated in service.
What does the water column connect in a boiler? The boiler to the gauge glass and low-water controls.
What is the difference between a pressure control used for The pressure control is used for normal cycling.
normal cycling and a safety high-limit device?
What is a common cause of scale buildup in an LWCO Sludge accumulation.
chamber?
What is the first action if no water is visible in the gauge Shut the burner down and determine true water level.
glass?
What is the purpose of bottom blowdown? To remove sediment from low points.
What is a common misconception about steam boilers? That they never need controls.
What should be done if a safety valve is frequently lifting? Investigate for control failure or overfiring.
What does the safety valve protect against? Overpressure in the boiler.
What is the main purpose of a safety valve? To prevent boiler overpressure.
What is the burner flame? The flame produced by the burner in a boiler, used to heat water and generate
steam.
What is the condensate tank? A tank that collects condensate, which is the water formed when steam cools and
condenses.
What is the feedwater line? A pipe that delivers water to the boiler for steam generation.
, NYC Custodian Engineer Practice Exam | Safety, Codes, HVAC, Plumbing & Maintenance | 2026-2027
What is the safety high-limit device? A safety mechanism that shuts down the boiler if the temperature exceeds a preset
limit.
What is a pressure control used for normal cycling? It is different from the safety high-limit device.
What does blowing down the water column confirm? The level passages are open and accurate.
What connects the boiler to the gauge glass? The water column.
What is the main purpose of a fuse? To protect a circuit by melting open during overcurrent.
What should you do if a breaker keeps tripping? Find and correct the cause.
What does grounding mainly help with? Stabilizing the system and reducing shock hazards.
What does bonding connect metal parts together for? So that fault current can clear safely.
What is a GFCI primarily intended to protect against? Ground-fault shock hazards.
What should exit signs do? Remain illuminated and maintained.
What is a relay best described as? An electrically operated switch.
What can overcurrent result from? An overload or a short circuit/fault.
What is the main purpose of a circuit breaker? To open the circuit during unsafe current.
What are signs of a bad switch or outlet? Flickering, buzzing, and a burning smell.
What should you think about if many fixtures in one area An upstream circuit or control issue.
are out?
