Case Study: Troubleshooting Rooftop Chiller Issues
In 2024, a major colocation facility in Northern Virginia began experiencing repeated failures in the compressors of one of their rooftop air-cooled chillers. Despite being a newly commissioned site, the system was struggling to maintain proper cooling — and the root cause wasn’t clear. The client called Purkay Labs to independently assess the airflow around the affected chiller and provide insight into what was going wrong.
Overview
The client was operating a large rooftop chiller system supporting multiple colocation tenants. While the chiller was functioning within spec in many respects, repeated compressor failures signaled that something was wrong in the local environment — particularly in how air was moving around the unit.
To investigate, Purkay Labs conducted a focused on-site assessment using the AUDIT-BUDDY system. The goal: determine whether airflow conditions around the chiller were contributing to premature compressor stress or failure.
The Project
Purkay Labs deployed two AUDIT-BUDDY systems and completed three separate sets of measurements over a single 6-hour window. Measurements were taken at four elevations:
104 inches
80 inches
57 inches
34 inches
Each AUDIT-BUDDY collected minute-by-minute data on temperature, humidity, and airflow characteristics at all four heights.
Our analysis included:
Static Heat Maps to capture point-in-time temperature distribution
Dynamic Heat Maps to reveal fluctuations and thermal layering over time
Recirculation Maps to visualize the percentage of hot exhaust air returning to the chiller intake
The Results
The data told a clear story: the rooftop chiller was experiencing significant recirculation of its own exhaust air.
Instead of dispersing away from the system, warm air from the chiller’s exhaust was being trapped by a nearby wall and the close placement of other rooftop chillers. This hot air looped back toward the chiller’s intake, raising the temperature of the incoming air and placing additional strain on the compressors.
The recirculation map showed a high percentage of exhaust air being pulled back into the intake — a known contributor to early compressor wear and efficiency loss.
Instead of dispersing away from the system, warm air from the chiller’s exhaust was being trapped by a nearby wall and the close placement of other rooftop chillers. This hot air looped back toward the chiller’s intake, raising the temperature of the incoming air and placing additional strain on the compressors.
The recirculation map showed a high percentage of exhaust air being pulled back into the intake — a known contributor to early compressor wear and efficiency loss.
Outcome
The insight from Purkay Labs enabled the client to move quickly on mitigation plans. Based on our findings, the facility is pursuing physical design modifications — such as adding exhaust hoods or redirecting airflow paths — to reduce recirculation and protect the chiller's performance.
The client has requested a follow-up audit after these modifications are implemented to verify improved airflow behavior and confirm the issue is resolved.
Summary
Purkay Labs' AUDIT-BUDDY system was instrumental in diagnosing a critical issue with the rooftop chiller at a major colocation facility in Northern Virginia. By providing accurate and detailed temperature data at multiple heights, Purkay Labs revealed a significant air recirculation problem that risked internal component failure. This data-driven approach allowed the client to plan necessary design changes to address the issue effectively. The client’s proactive engagement with Purkay Labs ensured that they had reliable, independent data to inform their decision-making and optimize their cooling infrastructure. The collaboration highlighted the value of the AUDIT-BUDDY system in identifying and resolving complex environmental challenges in data center operations.
About Purkay Labs
Purkay Labs helps data center operators and facility managers diagnose airflow and thermal issues that impact equipment reliability. Our portable AUDIT-BUDDY System delivers detailed, rack-level environmental data to identify hot spots, validate airflow performance, and support informed cooling decisions. Whether troubleshooting isolated problems or conducting full-site audits, Purkay Labs provides actionable insight that helps operators protect their infrastructure and optimize performance.
Contact us here to learn how we can help you independently evaluate your cooling strategies.