Describe a typical chiller plant sequence of operations in BAS.

Describe a typical chiller plant sequence of operations in BAS.

• A. Stop chiller immediately; disable pumps; set sensors to standby; ignore AHUs.
• B. Randomly adjust setpoints without sequence.
• C. Start all AHUs first, then chiller; disregard water loop temperatures.
• D. Start chiller; ensure condenser pumps and cooling towers; enable water loops; set leaving/chilled water temperatures; adjust VFDs on pumps; coordinate with AHUs to satisfy zone loads.

Answer: (D)

In BAS, the sequence of operations for a chiller plant is about coordinating equipment in a logical, interlocked order so the system can meet loads safely and efficiently. The best approach starts the chiller first, ensuring there is a source of chilled water. Then it brings condenser pumps and cooling towers online to reject heat, and enables the water loops so the system can circulate. With the loops active, it sets the leaving/chilled water temperatures to target values, and then trims the pump speeds with VFDs to match the actual demand. Finally, it coordinates with the AHUs to satisfy zone loads, so the cooled air delivered to spaces aligns with current cooling requirements. This sequence avoids trying to run AHUs without available chilled water or neglecting loop temperatures, which could cause discomfort and energy waste. Other approaches that stop equipment, adjust setpoints randomly, or start AHUs before the water loops are ready would lead to unsafe, inefficient operation and poor control of the space.

In BAS, the sequence of operations for a chiller plant is about coordinating equipment in a logical, interlocked order so the system can meet loads safely and efficiently. The best approach starts the chiller first, ensuring there is a source of chilled water. Then it brings condenser pumps and cooling towers online to reject heat, and enables the water loops so the system can circulate. With the loops active, it sets the leaving/chilled water temperatures to target values, and then trims the pump speeds with VFDs to match the actual demand. Finally, it coordinates with the AHUs to satisfy zone loads, so the cooled air delivered to spaces aligns with current cooling requirements. This sequence avoids trying to run AHUs without available chilled water or neglecting loop temperatures, which could cause discomfort and energy waste. Other approaches that stop equipment, adjust setpoints randomly, or start AHUs before the water loops are ready would lead to unsafe, inefficient operation and poor control of the space.