Case Study Summary
This case study examines how Apex stabilized a large resort and casino chilled water system experiencing corrosion, biofouling, and chemical instability. Through a comprehensive chilled loop remediation program, the facility significantly reduced iron levels, controlled biological activity, and restored long-term system reliability while minimizing maintenance disruptions.
Large hospitality facilities rely on chilled water systems to maintain guest comfort and HVAC reliability across expansive properties. When water chemistry becomes unstable, corrosion and biofouling can accelerate quickly, leading to equipment damage, filter plugging, and frequent maintenance events.
A large resort and casino in Nevada was experiencing persistent chilled water system issues, including elevated corrosion indicators, biological activity, and inconsistent chemical control. These conditions threatened HVAC performance and raised concerns about long-term asset protection. The facility partnered with Apex to diagnose the root causes and implement a corrective strategy focused on restoring system stability.
Results at a Glance
Iron Levels Reduced from Approximately 10.0 ppm to below 0.3 ppm.
Chilled Water pH stabilized from Corrosive conditions to Optimal Control range
Improved System Reliability with Reduced Maintenance and Filter plugging
Facility Background
- Industry: Hospitality [Resort & Casino]
- Application: Chilled Water Loop
- Challenge Area: HVAC System Optimization
- Apex Solution: Chilled loop remediation using corrosion inhibitors and non-oxidizing biocides
The facility operates a large chilled water loop supporting HVAC systems across the property. Prior to remediation, water analysis revealed elevated iron and copper levels, absence of effective corrosion inhibitors, and aggressive anaerobic biological activity, including sulfate-reducing bacteria (SRB) and denitrifying bacteria (DN). These conditions resulted in frequent filter plugging, reduced heat transfer efficiency, and increased maintenance demands.
The Challenge
The chilled water system faced several compounding challenges:
- Elevated iron and copper levels indicating active corrosion
- Persistent anaerobic bacterial activity contributing to metal loss
- Corrosive pH levels in the range of 6.1–6.3
- Frequent coil and filter plugging disrupting HVAC performance
- Lack of consistent corrosion inhibitor and biocide protection
Operations teams were also concerned that aggressive corrective actions could further destabilize the system if not carefully managed.
The Apex Solution
Apex implemented a comprehensive chilled water remediation and stabilization program designed to restore chemical balance while minimizing operational disruption.
Key elements of the solution included:
- Controlled system flushing to remove accumulated biofilm and corrosion products
- Application of non-oxidizing biocides to control anaerobic bacterial populations
- Introduction of targeted corrosion inhibitors, including molybdate, azole, and silicate blends, to protect carbon steel and yellow metals
- Adjustment of chemical feed strategies to establish long-term stability
- Enhanced monitoring of pH, conductivity, iron, and copper levels to verify performance
This phased approach allowed the system to transition from a corrosive, unstable condition to controlled, predictable operation.
Results & Operational Impact
Within six months of implementing the remediation program, the facility achieved measurable improvements:
- pH increased from corrosive conditions (6.1–6.3) to a stable 9.6, aligning with optimal chilled water operating ranges
- Iron concentrations decreased from approximately 10.0 ppm to between 0.11 and 0.3 ppm, indicating a significant reduction in active corrosion
- Copper levels stabilized within acceptable limits
- Molybdate levels reached 166–177 ppm, providing robust corrosion protection
- Azole concentrations increased to 88 ppm, exceeding recommended thresholds for yellow metal protection
- Filter plugging and maintenance disruptions were significantly reduced
As a result, the chilled water system now operates with minimal chemical adjustments and improved long-term reliability.
Applicable To
This solution is relevant for:
- Large hospitality, resort, and casino facilities
- Commercial buildings with extensive chilled water HVAC systems
- Facilities experiencing corrosion, biofouling, or unstable closed-loop chemistry
- Operations seeking to improve asset protection without major capital upgrades
Conclusion
This case study demonstrates how proactive chilled water remediation can reverse corrosion, control biological activity, and restore system stability in large hospitality environments. By implementing a data-driven treatment strategy, Apex helped this resort and casino protect critical HVAC assets, reduce maintenance burdens, and ensure reliable comfort for guests.
For facilities facing similar chilled water challenges, Apex delivers expertise and treatment programs that prioritize long-term performance and asset protection.
Frequently Asked Questions
Can chilled water corrosion be corrected without replacing system piping or equipment?
Yes. In this case, corrosion was addressed through chemical remediation, inhibitor protection, and biological control without requiring equipment replacement or system shutdowns.
Why is biological control important in closed-loop chilled water systems?
Anaerobic bacteria such as sulfate-reducing bacteria can accelerate corrosion and create unstable conditions. Targeted biocide programs are essential to maintaining long-term system health.
How long does it take to stabilize a severely corroded chilled water system?
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