When cooling demands increase in an existing facility, many building owners assume they have only one option: replace the entire air handling unit (AHU). However, full AHU replacement is often costly, disruptive, and time-consuming – particularly in facilities where extended downtime is unacceptable.
Recently, Marlo partnered with one of our Independent Manufacturer’s Representatives, HVAC Solutions, to help a large manufacturing company solve a significant cooling challenge. The project demonstrates how innovative engineering and custom coil design can deliver substantial performance improvements, while avoiding the expense and disruption of a complete system replacement.
The Challenge
The customer had a clear objective: increase the cooling capacity of an existing HVAC system by approximately 30%. On the surface, that might sound like a straightforward upgrade. In reality, the project presented several significant obstacles.
The existing air handling unit was located inside a penthouse structure on the facility’s roof. Replacing the AHU would have required not only purchasing a new unit, but also dismantling portions of the rooftop penthouse to remove the old equipment and install the replacement. Once the installation was complete, the penthouse would then need to be reconstructed.
Beyond the direct costs associated with new equipment and construction, the facility also faced the prospect of substantial downtime during the replacement process. For a large manufacturing operation, disruptions to environmental control systems can have significant operational and financial consequences. As a result, the customer was looking for a potential solution that would deliver the required cooling capacity increase without the cost and disruption of a new AHU.
Existing System Limitations
The existing AHU contained six chilled water coils arranged in two stacks of three coils each, with the traditional airflow blowing at 90 degrees across the coils. Simply replacing the existing coils with new coils of similar dimensions and arrangement would not provide the additional cooling capacity required. Plus, adding more coils in the existing configuration was not possible due to limited space inside the unit.
Based on the circumstances, it was clear that a truly unique solution was needed, and one that would require a completely different way of thinking about coil arrangement and airflow management.
Developing an Innovative Solution
Working closely with HVAC Solutions, the Marlo engineering team evaluated the physical constraints of the air handler and explored alternatives to conventional coil layouts.
Rather than attempting to squeeze more capacity from the existing six-coil configuration, the team developed a solution that fundamentally changed how the coils were positioned within the unit.
The new design increased the number of chilled water coils from six to twelve. While this may not seem possible due to space constraints, the engineering team was able to make it happen by reimagining the airflow path and coil arrangement.
Instead of maintaining the traditional two-stack arrangement with airflow passing through the coils at a 90-degree angle, the new design utilized four stacks of three coils arranged in a staggered “zig-zag” configuration. Airflow was directed through the coils at an angle, which effectively doubled the coil surface area – within the same footprint – providing the needed boost in cooling capacity (with the addition of supplemental fans, as well).
Custom Modules Designed for Serviceability
Performance was obviously the number one consideration on this project, but the Marlo engineering team also wanted to ensure that future maintenance would be as simple as possible with the new complex coil configuration. To accomplish this, they designed and fabricated custom modules and support frames that positioned each coil at the required angle, while maintaining accessibility.
The new design offered a significant advantage, allowing any of the twelve coils to be removed and replaced individually, without requiring the removal of adjacent coils. This service-friendly approach will reduce future maintenance time and minimize disruption should a coil ever require replacement in the future.
On-Site Support Through Installation
Due to the complexity of the retrofit, members of the Marlo team were present on-site during installation to support the process. Providing engineering support during installation helped ensure that the custom modules and coil assemblies were installed correctly and performed as intended. For projects involving highly customized solutions, collaboration between the manufacturer, representative, contractor, and end user is often critical to achieving a successful outcome – and Marlo is always happy to participate in the entire process.
The Result
The manufacturing facility achieved its goal of increasing cooling capacity by approximately 30% without replacing the entire air handling unit. By avoiding a complete AHU replacement, the customer was able to:
- Eliminate the cost of a new air handler
- Avoid extensive rooftop penthouse reconstruction
- Minimize operational downtime
- Increase cooling capacity to meet growing demands
- Preserve future serviceability through a modular coil design
When Standard Solutions Aren’t Enough, there’s Marlo
This project serves as an excellent example of how innovative coil design can unlock new capacity, extend equipment life, and help customers avoid costly AHU replacements.
When faced with a difficult HVAC challenge, sometimes the best solution isn’t replacing the system – it’s rethinking what’s possible within it. By rethinking airflow patterns and maximizing heat transfer surface area, the team was able to achieve a substantial performance increase without replacing the entire unit.
At Marlo, we work closely with our representatives – as well as contractors, engineers, and facility owners – to develop custom coil solutions that address difficult challenges. When you have an HVAC problem that requires a unique solution, give our team the chance to work on it. Chances are, we’ll be able to give you exactly what you need.
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