How does chiller sequencing logic work in a BAS?

How does chiller sequencing logic work in a BAS?

• A. It runs all chillers at full capacity regardless of demand.
• B. It starts chillers based on cooling demand, using staging and priority to optimize efficiency and redundancy.
• C. It sequences chillers randomly without considering load.
• D. It starts chillers only during night hours to save energy.

Answer: (B)

Chiller sequencing logic in a BAS is about matching cooling capacity to the actual demand in the most efficient and reliable way. The system continuously monitors the cooling load and decides which chillers to run and in what order. As demand rises, additional chillers are brought online in stages, typically starting with the most efficient unit or a designated lead unit, while the others remain as back-up or lag units. This approach optimizes energy use, reduces unnecessary runtime, balances wear across equipment, and preserves redundancy so a single unit failure doesn’t cripple cooling. The controller also enforces practical constraints like minimum on/off times and smooth transitions between stages to avoid short-cycling and maintain stable supply temperatures. Running all chillers at full capacity or seeding the system with random sequencing would waste energy and undermine reliability, while limiting operation to night hours wouldn’t meet daytime cooling needs.

Chiller sequencing logic in a BAS is about matching cooling capacity to the actual demand in the most efficient and reliable way. The system continuously monitors the cooling load and decides which chillers to run and in what order. As demand rises, additional chillers are brought online in stages, typically starting with the most efficient unit or a designated lead unit, while the others remain as back-up or lag units. This approach optimizes energy use, reduces unnecessary runtime, balances wear across equipment, and preserves redundancy so a single unit failure doesn’t cripple cooling. The controller also enforces practical constraints like minimum on/off times and smooth transitions between stages to avoid short-cycling and maintain stable supply temperatures. Running all chillers at full capacity or seeding the system with random sequencing would waste energy and undermine reliability, while limiting operation to night hours wouldn’t meet daytime cooling needs.