HVAC TAB & Functional Testing 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 HVAC TAB & Functional Testing flashcards as text
A hydronic system's pump is producing design flow but inadequate head pressure. What does this most likely indicate?
Answer: Pump impeller wear or incorrect impeller installed
When flow is correct but head is insufficient, pump impeller wear or an incorrectly sized impeller reduces the pump's ability to develop pressure.
During functional testing of an economizer, what outdoor air condition triggers the changeover from economizer to mechanical cooling?
Answer: When outdoor air enthalpy or temperature exceeds the high-limit setpoint
The economizer high-limit setpoint (enthalpy or dry-bulb) triggers changeover to mechanical cooling when outdoor conditions are no longer suitable for free cooling.
What is the acceptable tolerance for air balancing of supply terminals per NEBB procedural standards?
Answer: +/- 10% of design
NEBB procedural standards specify a +/- 10% tolerance for supply air terminal balancing as the acceptable variance from design airflow.
During commissioning functional testing, a cooling tower bypass valve is tested. What scenario verifies correct control sequence?
Answer: Valve modulates to maintain condenser water supply temperature at setpoint
Correct cooling tower bypass valve operation modulates to maintain condenser water supply temperature at design setpoint across varying outdoor conditions.
Which of the following best describes the difference between TAB and commissioning functional testing?
Answer: TAB quantifies and adjusts flows to design; commissioning verifies sequence of operations
TAB quantifies, adjusts, and documents fluid flow rates to match design; commissioning functional testing verifies that systems operate correctly through all control sequences.
A dual-duct VAV system's hot deck is providing 10°F less than design heating supply temperature. What component should be investigated first?
Answer: Heating coil control valve and actuator operation
Insufficient hot deck temperature is most directly caused by a control valve not fully opening or an actuator failure limiting heating coil flow.
When conducting a duct leakage test, what does a high leakage class (CL) value indicate?
Answer: Greater allowed leakage per unit of surface area
SMACNA leakage class (CL) values indicate maximum allowable leakage — a higher CL means more leakage is permitted per unit of duct surface area at test pressure.