By MICHAEL WARADY, CEO, EAI Water
A closed-loop heating system should, in theory, be one of the most stable components of a building or facility’s infrastructure. It operates in isolation, doesn’t evaporate water like an open cooling system, and shouldn’t be exposed to outside contaminants.
Yet, despite these advantages, many closed-loop networks quietly degrade over time, losing efficiency and developing costly mechanical issues that are often misdiagnosed as routine wear and tear.
Years ago, at a client’s Central Utility Plant, system operators had noticed subtle but persistent issues—pumps working harder than usual, fluctuating differential pressures, and gradual declines in heat transfer efficiency. No major leaks had been detected, and on paper, the system had been running as expected. But when they pulled a water sample, the issue became clear.
Corrosion debris was circulating through the network, pH levels had drifted outside the ideal range, and biofilm had begun forming in low-flow sections of the system.
So the problem wasn’t mechanical—it was chemical.
Despite following a standard inhibitor treatment program, the system’s water chemistry had never been fully optimized. Over time, the facility did several rounds of retrofits and additions to the system – inadvertently leading to dead legs, open valves leading to contamination, and unchecked microbial activity that slowly degraded internal piping and heat exchangers. The system was doing exactly what it had been designed to do—circulate water efficiently—but the chemistry behind that water had been slowly working against it.
This isn’t an isolated case. Across commercial and industrial heating networks, the misconception that closed loops are low maintenance has led to widespread failures that could be avoided with a more precise approach to water chemistry.
Why Closed-Loop Systems Aren’t as Stable as They Seem
There’s a reason so many facility teams assume closed-loop systems are set-and-forget infrastructure. Unlike open cooling towers, they don’t evaporate water, don’t require frequent blowdown cycles, and aren’t constantly exposed to fresh contaminants.
And oftentimes consulting engineers describe these systems as such. But that assumption ignores the reality of internal chemical degradation, slow water loss, and minor oxygen ingress—all of which gradually destabilize system conditions over time.
One of the most common and underestimated issues is oxygen infiltration. Even in a well-sealed system, air can enter through leaks, valve adjustments and turning, or pressure fluctuations. Once inside, oxygen reacts with system metals, producing corrosion byproducts that circulate through the network, potentially clogging strainers, reducing pump efficiency, and fouling heat exchangers.
Another issue that often goes unnoticed is pH instability.
Many closed-loop systems experience gradual shifts in alkalinity due to chemical mismanagement, makeup water additions, or internal reactions with system materials. If pH drops too low, acidic conditions accelerate metal degradation. If pH drifts too high, scale forms on heat transfer surfaces, reducing efficiency and forcing the system to work harder to maintain setpoints.
Microbiological fouling is also a factor, though it’s rarely addressed in closed-loop treatment programs. Low-flow sections, stagnant backup piping, and underutilized loops create ideal environments for biofilm to develop. Once biofilm forms, it acts as an insulator, reducing heat exchanger efficiency while creating pockets of localized under-deposit corrosion.
A district heating system in a commercial development recently encountered these exact issues. Over time, the facility managers had begun noticing higher energy consumption, flow imbalances, and declining pump efficiency. When they finally investigated, they found a combination of oxygen-induced corrosion, unbalanced pH, and microbial growth—factors that had gone undetected for years because standard water treatment protocols weren’t addressing the real problem.
Why Optimizing Water Chemistry is the Key to Longevity
A well-maintained closed-loop system isn’t just one that’s flushed periodically and dosed with inhibitors—it’s one where water chemistry is actively managed to prevent long-term degradation. The difference between a system that operates efficiently for decades and one that develops premature failures often comes down to how well pH, corrosion control, and microbial activity are balanced.
Facilities that take a proactive approach to closed-loop water chemistry focus on stabilizing pH, controlling oxygen levels, using tailored corrosion inhibitors that match the system’s metallurgy, and working with a licensed water treatment professional to help support and provide best practices to facility managers.
Rather than relying on scheduled flushes and reactive chemical dosing, these systems are monitored dynamically, with adjustments made in response to real-time conditions rather than predetermined maintenance intervals.
A commercial high-rise in Southern California that brought EAI on board saw immediate improvements in system performance. By optimizing pH, fine-tuning corrosion inhibitor dosing, installing corrosion coupon racks, and addressing minor leaks that had been allowing oxygen ingress, they extended heat exchanger lifespan, reduced pumping energy, and stabilized temperature fluctuations across the network.
Despite the clear advantages of proactive water chemistry management, many facility teams continue operating under the assumption that closed-loop systems don’t require ongoing oversight. The result? Accelerated corrosion, biofilm formation, and efficiency loss that could have been prevented with a more precise approach to water treatment.
The Critical Role of Licensed Water Treatment Professionals
While chemical optimization is essential for closed-loop system performance, equally important is having the right expertise to manage these complex chemical interactions. A licensed, certified water treatment professional (preferably someone with a CWT certification) brings more than just chemical knowledge – they provide the experience, technical understanding, and systematic approach needed to maintain long-term system stability.
A large-scale district heating provider discovered this firsthand when they switched from an in-house maintenance approach to partnering with a CWT. For years, their closed-loop network had suffered from gradual circulation inefficiencies and unexplained corrosion issues. Despite following standard chemical treatment protocols, they couldn't achieve stable system performance. The missing element wasn't better chemicals – it was the expertise of having experienced professionals diagnosing, and solving these issues in the past.
Licensed water treatment professionals bring several crucial advantages to closed-loop system management. First, they understand the intricate relationship between system metallurgy, operational conditions, and chemical treatment programs. This allows them to develop tailored solutions that account for specific system characteristics rather than applying a one-size-fits-all approach.
Second, certified professionals have extensive experience identifying early warning signs of system degradation. They can spot subtle indicators that might go unnoticed by general maintenance staff. This early detection capability often prevents small issues from developing into costly system failures.
Third, professional water treaters are required to maintain current knowledge of industry best practices, emerging technologies, and evolving treatment methods. As regulations change and new treatment options become available, they ensure that facility system partners remain both compliant and efficient. Their ongoing education and certification requirements mean they're continuously updating their expertise to match industry advancements.
Perhaps most importantly, licensed professionals understand that effective water treatment isn't just about adding chemicals – it's about developing comprehensive management strategies with their clients. With that in mind, they help establish monitoring protocols, implement preventive maintenance schedules, and create documentation systems that ensure consistent system performance over time. Their systematic approach transforms water treatment from a periodic maintenance task into a cornerstone of facility operations.
At an East Coast university campus, the transition to professional water treatment management led to immediate improvements in their heating network efficiency. The water treater identified oxygen ingress points that had been overlooked, implemented a more precise chemical monitoring program, and established clear protocols for system baselining and tracking. Within months, they saw reduced energy consumption, improved heat transfer efficiency, and more stable system operation.
Engineering Better Water Treatment for Future Heating Systems
As heating networks become more complex and energy efficiency remains a top priority, water treatment programs will need to evolve beyond traditional inhibitor dosing and occasionalflushing cycles. The next generation of closed-loop systems will be designed with water chemistry management as an integral component, rather than a reactive maintenance function.
Some commercial developments are already adopting real-time chemical monitoring, ensuring that corrosion inhibitors, pH stabilizers, and oxygen scavengers are continuously optimized. Instead of relying on manual testing, these systems provide dynamic feedback, allowing facility managers to make real-time adjustments to maintain ideal conditions.
In some high-performance heating networks, advanced filtration and side-stream separation technologies are being integrated to remove corrosion byproducts before they accumulate and foul system components. This shift from passive treatment to active water management is setting the standard for the next generation of facility operations.
As regulations tighten and energy efficiency expectations grow, buildings that fail to implement proactive closed-loop water treatment strategies will face rising operational costs, shortened equipment lifespans, and increasing compliance challenges. The cost of inaction is not just higher maintenance—it’s premature system failure and long-term infrastructure degradation.
The facilities that invest in quality chemical selection and continuous, professional oversight will operate at higher efficiency for years to come and protect the initial investment into this infrastructure.
Those that continue relying on outdated assumptions about closed-loop stability will face the consequences of slow but inevitable system decline.
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Author Michael Warady is CEO of Economic Alternatives, Inc. (www.eaiwater.com), a total water solutions provider out of Southern California. A graduate of Duke University with two masters degrees from Yale University, he is also president and co-founder of Sylmar Group.