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
A chilled water system is experiencing low delta-T syndrome. Which of the following conditions is the PRIMARY cause?
Answer: Control valves failing to modulate properly at part load
Low delta-T syndrome is most commonly caused by control valves failing to fully close at part load, allowing warm return water to mix with supply water.
During performance testing of a centrifugal pump, the flow rate is lower than design. Which diagnostic step should be taken FIRST?
Answer: Verify actual pump curve against the system curve
Verifying the actual pump curve against the system curve identifies whether the issue lies with the pump itself or the system resistance.
What is the significance of the 'equal percentage' characteristic in a control valve?
Answer: Each increment of valve stroke produces an equal percentage change in flow
An equal percentage valve produces a flow change that is a fixed percentage of the current flow for each increment of stem travel, providing good controllability at part load.
When commissioning a variable air volume (VAV) system, the diversity factor is used to:
Answer: Determine the ratio of maximum simultaneous zone airflow to total installed terminal capacity
The diversity factor accounts for the fact that not all VAV terminals will be at maximum demand simultaneously, allowing the central AHU to be sized smaller.
A cooling tower's approach temperature is defined as:
Answer: Difference between leaving cold water and entering wet bulb
Approach temperature is the difference between the tower's leaving cold water temperature and the ambient wet-bulb temperature, indicating tower effectiveness.
In a hydronic system, what does a negative differential pressure reading across a coil indicate?
Answer: Reverse flow through the coil due to improper valve sequencing or piping
Negative differential pressure across a coil indicates reverse flow, typically caused by improper two-way valve sequencing or cross-connected piping.
The Integrated Energy Efficiency Ratio (IEER) for cooling equipment differs from EER in that IEER:
Answer: Accounts for part-load performance at multiple operating conditions
IEER is a weighted average of efficiency at four part-load conditions (100%, 75%, 50%, 25%), better representing real-world performance than single-point EER.