Advertised vs. Actual: The Massive Pool Chiller Performance Gap

Understanding Chiller Power

For context, chiller power is measured in kilowatts (kW) - a measurement of heat removal capacity. The kW rating tells you how many kilowatts of heat a unit can remove at one time.

Example: Our biggest chiller is 17.42kW - meaning it can remove 17.42kW of heat simultaneously. That’s enough cooling power for 31.67 swimmers at once (assuming no other heat sources, which is never the case in real-world conditions).

Yet somehow, our 17.42kW chiller is replacing and substantially outperforming units advertised as 20kW, 35kW, and even 65kW systems. How is this possible?

The Heating vs. Cooling Bait-and-Switch

Put simply, most “chillers” on the market are primarily designed to heat water, not cool it.

While these units can operate in reverse to chill water, their efficiency and power drop substantially in cooling mode. It’s like expecting a car to perform as well in reverse as it does driving forward - the entire system is optimised for one direction.

And on top of that, warming water is substantially easier than chilling it.

The Performance Gap

When these heat pumps are switched to cooling mode, they immediately lose about 50% of their advertised kW rating. A “65kW” system instantly becomes a ~30kW system.

But it gets worse. As the water temperature drops, cooling efficiency plummets even further.

Here are the actual measured cooling capacities at 10°C water temperature:

• “65kW” system = 9.7kW actual cooling (85% less than advertised)
• “35kW” system = 3.495kW actual cooling (90% less than advertised)
• “20kW” system = 2.87kW actual cooling (86% less than advertised)

And the reason it was measured at 10 degrees is because the chillers couldn’t get the water any colder.

This massive performance gap explains why these systems couldn’t maintain target pool temperatures, had to run at maximum capacity 24/7, and burned out prematurely.

What This Means For You

If you’re considering a pool chiller or dealing with cooling problems, understand that the advertised kW rating may have almost nothing to do with actual cooling performance. Always ask for the specific cooling capacity at your target water temperature before making any decisions.