January 22, 2026

Chiller Plant Efficiency Series – Cooling Tower Efficiency Part 1

The main purpose of a cooling tower is to cool the warm condenser water coming from the chiller so that it returns colder to the condenser.

In this part, we will explore the factors that drive the cooling effect in a cooling tower. In Part 2, we will discuss the difference between cooling tower thermodynamical efficiency and electrical efficiency (kW/ton).

Pump Efficiency Is About Operating Point, Not Speed

Most chilled water plants use variable speed pumps with a constant differential pressure (DP) setpoint.  Many use an improved DP Reset approach. On paper, this sounds efficient. In practice, pump efficiency depends entirely on where the operating point lands on the pump curve—and that point moves more than most people realize.

Chiller Plant Efficiency Series – Cooling Tower Efficiency Part 1

The main purpose of a cooling tower is to cool the warm condenser water coming from the chiller so that it returns colder to the condenser.

In this part, we will explore the factors that drive the cooling effect in a cooling tower. In Part 2, we will discuss the difference between cooling tower thermodynamical efficiency and electrical efficiency (kW/ton).

Pump Efficiency Is About Operating Point, Not Speed

Most chilled water plants use variable speed pumps with a constant differential pressure (DP) setpoint.  Many use an improved DP Reset approach. On paper, this sounds efficient. In practice, pump efficiency depends entirely on where the operating point lands on the pump curve—and that point moves more than most people realize.