Why Chillers Struggle in Summer and What to Check

John McCoy, Tech Support Manager

Our technical support team spends a lot of time helping customers troubleshoot cooling challenges, improve efficiency, and get the most from their equipment. In this edition of Ask G&D, we sat down with John from G&D Chillers to answer some of the most common questions he hears from customers.

How do I know if my chiller is properly sized?

This is one of the most common questions we get, and the answer is that tonnage or BTU ratings alone don’t tell the whole story.

To determine whether a chiller is properly sized, you need to look at the entire system: the actual heat load, tank sizes, heat exchangers, flow rates, insulation, and how the process behaves throughout the day. Every one of those factors contributes to the overall cooling demand.

A lot of systems we evaluate aren’t actually undersized. They’re just not fully aligned with how they’re being used. When that happens, even a chiller that’s operating perfectly can struggle to keep up.

The key is looking beyond the nameplate rating and understanding how the complete process performs in real-world conditions.

Why does my system struggle more in the summer?

Honestly, this one is pretty simple: it’s harder to reject heat when it’s already hot outside.

Many chillers operate close to their maximum capacity under normal conditions. When summer temperatures rise, that additional heat load can be enough to push the system beyond its comfort zone.

In most cases, summer isn’t actually causing the cooling issue. It’s exposing the fact that the system was already operating very close to its capacity limit.

If your chiller consistently struggles during the hottest months, it’s worth evaluating whether your cooling load has increased over time or if the system is operating with enough margin to handle seasonal changes.

What causes inconsistent cooling?

Most of the time, inconsistent cooling comes back to process control and stability.

While maintenance issues can certainly affect performance, what we typically see is variation in the process load itself. Whether you’re running a brewery, winery, distillery, or another industrial cooling application, the cooling demand is constantly changing.

In a perfect world, a chiller would see the same load all day, every day. Of course, that’s rarely how real production environments work.

If the process experiences frequent swings in load, flow, or operating conditions, those fluctuations will show up in the chiller’s performance as well. The two are directly connected.

When a system isn’t designed with stability and control in mind, you’ll often see temperature swings and inconsistent cooling performance.

How can I reduce water or energy usage?

In many cases, the biggest gains come from improving process control rather than replacing equipment.

When a chilled water system is properly configured and operating efficiently, you’ll typically see more stable temperatures, less wasted water, and improved electrical efficiency.

Reducing variables within the process is often the most effective place to start. Improving flow control, tightening operating parameters, and eliminating unnecessary inefficiencies can make a significant difference.

Before investing in major equipment upgrades, it’s worth taking a close look at how the overall system is operating. Small process improvements often deliver meaningful savings.

When should I upgrade my system?

This question comes up more often than people think.

Sometimes the signs are obvious. Your chiller may struggle during warmer weather, cooling performance may become inconsistent, or your production demands may have increased since the system was originally installed.

In other cases, the decision comes down to age and maintenance. We have equipment in the field that’s been running reliably for 20 to 30 years, but eventually every system reaches a point where maintenance costs and operational demands need to be evaluated together.

You may have added tanks, expanded production, or increased process loads over time. If that’s the case, it may be worth stepping back and looking at the entire system to determine whether an upgrade, replacement, or system expansion makes sense.

The goal isn’t necessarily to replace equipment—it’s to make sure your cooling system continues to support your production goals efficiently and reliably.

Final Thoughts

One of the biggest misconceptions we see is the assumption that cooling problems are caused by a single piece of equipment.

In reality, performance depends on how the entire system works together—chiller, process, plumbing, tanks, controls, and flow rates.

When load, flow, and control are properly aligned, the equipment typically performs exactly as intended.

That’s why we spend so much time working with customers to understand the complete picture. Sometimes the solution isn’t a larger chiller or a major upgrade. Sometimes it’s simply making sure every part of the system is working together the way it should.

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