When Automated Control Wasn’t in Control: Restoring Predictable Cooling Tower Operation

At a glance

A commercial facility experienced unstable cooling tower chemistry and excessive water loss caused by uncontrolled blowdown. Guardian identified a control configuration failure that bypassed effective feedback, defined corrective actions, and restored predictable water and treatment control.

Key metrics

LOSS OF CONTROL CORRECTED

WATER AND TREATMENT USE STABILIZED

PLANNED OPERATION RESTORED

How blowdown control keeps a cooling tower in balance

A cooling tower loses water to evaporation, which concentrates the minerals left behind. Blowdown, or bleed, removes some of that concentrated water so fresh makeup can dilute it. A conductivity controller normally decides when to bleed, based on how concentrated the water has become.

When that control works, the tower runs at steady cycles of concentration and the treatment program can be dosed to a known target. When it does not, the tower either bleeds too little and scales, or bleeds all the time and wastes water and chemical.

This commercial facility’s 20,000 L condenser system was bleeding continuously. Chemistry kept drifting, especially through peak summer load, and the team could not tell what the system really needed.

Challenges

Continuous bleed from a 20,000 L condenser drove unnecessary water loss, destabilized chemistry, and prevented stable cycles of concentration—especially through peak summer operation. This increased operating costs and elevated the risk of scale, corrosion, and biological instability.

Solutions

Guardian conducted a site review and traced the issue to a conductivity controller misconfigured to drive a bleed valve through a secondary controller, bypassing proper feedback control. The bleed path and control logic were documented, and corrective actions were defined to restore direct, governed conductivity-based blowdown and re-establish controllable water and treatment balance.

Results

Stable operating control restored: The cooling tower returned to predictable operation, allowing chemistry to be maintained within target ranges rather than chasing drift.

Unnecessary water and chemical loss stopped: Corrected blowdown control eliminated continuous bleed, reducing waste and restoring meaningful cycles of concentration.

Operational risk reduced: With controlled blowdown and stable chemistry, risks associated with scale, corrosion, and biological instability were materially reduced.

Data

The cooling tower was operating with uncontrolled blowdown due to a misconfigured control sequence that bypassed effective feedback. As a result, water and treatment were continuously lost, cycles of concentration could not be stabilized, and true system demand was obscured—particularly during peak summer operation. Correcting the control logic restored predictable operation, allowing chemistry and water use to be managed intentionally rather than reactively.

Frequently asked questions

What was causing the continuous bleed?

The conductivity controller had been set up to drive the bleed valve through a secondary controller. That bypassed proper feedback control, so blowdown was no longer tied to actual water conditions.

What did Guardian do?

Reviewed the site, traced and documented the bleed path and control logic, and defined corrective actions to restore direct conductivity-based blowdown.

What changed once control was restored?

Continuous bleed stopped, cycles of concentration could be held, and chemistry stayed within target ranges instead of drifting.

Why does uncontrolled blowdown matter?

It wastes water and treatment chemical, hides the system’s true demand, and raises the risk of scale, corrosion and biological problems.