Why many chillers in the field are “technically correct but still don’t work properly”

This is a case I still remember clearly. It was an injection molding plant in Southeast Asia.

To be honest, at the beginning we also thought this project would not have any issues.

The specifications were complete.
Cooling capacity was sufficient.
Flow rate matched the design.
The brand was reliable.
The temperature setpoint was normal.

The customer was already preparing for stable production.

But within one month of operation, problems started to appear.

At first, nobody suspected a system issue

In the first few weeks after commissioning, everything looked normal.

Temperature control was stable, and there were no alarms.

But injection molding is not a steady load process. It is highly variable.

As production ramped up during daytime operation, issues slowly appeared:

• Temperature started to drift slightly
• Cycle time became longer
• Product consistency became worse
• Scrap rate increased

At the beginning, everyone assumed it was a process adjustment issue.

No one immediately questioned the chiller system.

The initial assumption: is the cooling capacity insufficient?

This is usually the first reaction on site.

“Is the chiller undersized?”

However, after reviewing the system in detail, we found something important.

The chiller itself was not the issue, and there was still capacity margin.

The real problem was one layer earlier: the design assumptions.

The real mistake: the system was designed based on average load

The design followed a standard engineering approach:

Average load → system design → equipment selection

The problem is that real production does not operate on averages.

In reality:

• Injection molding is a cyclic and impact load process
• Ambient temperature is significantly higher during daytime operation
• Thermal load is not smooth, but fluctuating and stepped

In other words, the system was designed in an “average condition world”, but operated in a “peak condition world”.

A key issue: ΔT was set too aggressively

In this project, ΔT was designed too small in order to improve efficiency.

On paper, it looked like an optimization.

But in real operation, it created an unintended consequence.

Flow rate remained continuously high during operation.

As a result:

• The pump operated close to its limit
• Return water temperature became unstable
• Heat exchange efficiency fluctuated

At this point, the conclusion was clear:

This was not an equipment issue. It was a system structure issue caused by an incorrect ΔT assumption.

Another issue: pressure drop did not match the real system

On drawings, the piping system looked clean and simple.

But in real installation, the situation changed:

• Additional valves were added
• Piping routes were modified
• More elbows and local resistance points were introduced

These changes are very common in construction, but were not updated in the design.

As a result:

Actual pressure drop was significantly higher than design values.

This caused:

• Reduced flow rate
• Pump operating away from its optimal efficiency point
• Lower system performance stability

But on site, the most common assumption was still:

“Is the chiller unstable?”

The third issue: peak load was not properly considered

This is the most critical factor.

The design was based on average load conditions.

However, the actual factory operation was:

• Cyclic injection molding loads
• Sudden thermal spikes
• No buffer capacity in the system

As a result:

The average load looked acceptable, but peak load exceeded system capacity limits.

This is why the system did not fail immediately. It degraded gradually.

A typical pattern of failure over time

This system followed a very typical pattern:

• Week 1: completely normal
• Week 3: occasional fluctuations
• Week 6: product quality instability begins
• Week 8: production rhythm is affected

The most dangerous type of problem is not sudden failure. It is gradual deviation.

The key decision point: replace equipment or review system logic

At that stage, the customer was already considering replacing the chiller with a larger unit.

We recommended not changing the equipment first, and instead reviewing the system logic.

We focused on three checks:

• Recalculate load based on peak conditions instead of average load
• Adjust ΔT to bring the system back into a stable operating range rather than an efficiency optimized point
• Recalculate real pressure drop and correct the pump operating point based on actual installation conditions

Final result

After the adjustments:

• Temperature stability recovered
• Production cycle returned to normal
• Product consistency improved
• The system returned to stable operation

No main equipment was replaced.

Key conclusion from this project

Chiller selection is not an equipment sizing problem.

It is a system assumption problem.

Because in real industrial environments:

• Load changes
• Ambient conditions change
• Piping conditions change
• Operating behavior changes

Any incorrect assumption in the early stage will eventually appear as a field problem.

If you are evaluating a system or experiencing instability

You can ask your supplier a few direct questions:

• Is the design based on average load or peak load
• How was ΔT determined in real engineering terms
• Is pressure drop based on actual piping or simplified assumptions
• Has local climate condition been properly considered

If these cannot be clearly explained, the risk is already embedded in the system.

How we approach projects at JECICOOL

At JECICOOL, we do not start from equipment selection.

We start from system logic:

• Real load structure decomposition, not only kW rating
• Separation of peak and average load calculation
• Hydraulic system verification
• Local environmental correction (temperature, humidity, altitude)
• Electrical system compatibility (50Hz / 60Hz)

Because in real engineering work:

The chiller is only the result. System logic is the root cause.

If you are currently evaluating a project or experiencing unstable operation

You can share the following information with us:

• Application type (injection molding, laser, chemical, HVAC, etc.)
• Temperature range
• Required cooling capacity or flow rate
• Location / country

We can help you quickly identify whether the issue is:

• Incorrect load model
• System design risk
• Selection mismatch
• Hydraulic bottleneck

Email: sales@jecicool.com
Website: https://www.jecicool.com

In field engineering, equipment rarely fails suddenly. Systems simply drift away from reality over time.