Building Systems Operation and Maintenance
This domain tests how you keep HVAC, mechanical, electrical, plumbing, and elevator systems safe, efficient, and reliable in occupied NYC buildings. Questions focus on preventive maintenance, troubleshooting, controls, water treatment, and the inspections that keep operating certificates valid.
Core operating rules
- HVAC: confirm ventilation and outdoor-air intake, change filters on differential pressure, clean coils and drains, and trend supply/return ΔT and static pressure. A low chilled-water ΔT often means bypass, fouled tubes, or low load-not a bad chiller.
- Boilers and chillers: log combustion efficiency, refrigerant charge, approach temperatures, and water-treatment results. Safety controls are not adjustments; find the cause before resetting.
- Electrical: infrared-scan panels under load, torque terminations, exercise generators and ATS monthly, and keep arc-flash labels and one-line drawings current.
- Plumbing: test backflow preventers annually, control booster-pump cycling, and manage Legionella risk in cooling towers and domestic hot water under the NYC cooling-tower rules.
- Elevators: maintenance must be performed by licensed elevator personnel; annual Category 1 and five-year Category 5 inspections are filed with DOB. Do not let building staff reset elevator faults beyond authorized procedures.
- CMMS discipline: record readings and corrective action, not just 'unit OK'.
Worked example
A supply fan draws 15 hp at 1,200 rpm. Balanced airflow needs 1,000 rpm. By the fan laws, power varies with the cube of speed: 15 × (1,000/1,200)^3 = 15 × 0.579 = 8.7 hp. That suggests a smaller motor or VFD saving, but first verify actual static pressure, motor service factor, and minimum ventilation; the calculated reduction is not a guarantee.
Traps that cost marks
- Assuming nameplate tonnage equals delivered capacity.
- Resetting a high-pressure or low-water safety control without finding the root cause.
- Confusing static pressure with velocity pressure.
- Treating elevator or backflow inspections as paperwork rather than operating requirements.