Systems & Equipment Performance Flashcards
7 cards from real CCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Systems & Equipment Performance flashcards as text
When measuring total airflow using the pitot tube traverse method in a rectangular duct, ASHRAE recommends a minimum of how many measurement points per log-linear traverse?
Answer: 8 total points minimum
ASHRAE recommends a minimum of 8 measurement points per traverse (log-linear distribution) for rectangular ducts under standard conditions.
In a building automation system, the term 'hunting' in a control loop refers to:
Answer: Continuous oscillation of the controlled variable around the setpoint
Hunting describes persistent oscillation of the controlled variable around setpoint, typically caused by excessive proportional gain or insufficient integral action.
During commissioning of a dedicated outdoor air system (DOAS), dew point control is critical because:
Answer: Delivering air above the space dew point prevents condensation on surfaces and sensible zone cooling units
DOAS systems must deliver dehumidified air below the space dew point to prevent surface condensation on radiant panels or chilled beams handling sensible loads.
What is the purpose of a low-limit (freeze-stat) controller on an air handling unit?
Answer: To prevent coil freezing by shutting the AHU when mixed air temperature drops too low
A freeze-stat shuts down the AHU and closes outdoor air dampers when mixed air temperature falls to the freeze threshold, protecting the heating/cooling coil from freeze damage.
A chilled water plant's kW/ton measurement during acceptance testing is higher than specified. Which of the following would MOST directly improve this metric?
Answer: Lower the cooling tower setpoint to reduce entering condenser water temperature
Lowering condenser water temperature reduces the compressor lift, directly improving chiller efficiency and the overall plant kW/ton.
In a steam distribution system, steam traps should be tested for failure modes. A trap that is stuck open will cause:
Answer: Excessive steam blow-through and energy waste
A steam trap stuck open allows live steam to pass into the condensate return, wasting significant energy and potentially damaging condensate return equipment.
During functional performance testing of a packaged DX unit, subcooling at the condenser outlet should typically be:
Answer: 5-15°F below saturation temperature
Subcooling of 5-15°F below saturation confirms a full liquid seal at the expansion device inlet, preventing flash gas that reduces system capacity.