In all large buildings, chillers are big-ticket items. They are at the heart of cooling applications around the world. In most facilities, they are among the most expensive devices that majorly contribute to excessive power usage. So, it is natural that such expensive and energy consuming equipment would be designed to serve for 20 to 25 years.
Although there is no clear standard to determine how long a chiller should operate, most manufacturers recommend replacement after approximately 15 to 20 years of service. And in fact, some chillers operate for such a long period of time if they are allowed to operate in a favourable environment under prescribed duty conditions.
Therefore, when it comes to making the decision to replace the chiller prematurely it is not so easy to proceed. Just because a chiller is operating does not mean it is working efficiently. Therefore, the notion that if the chiller is running, it is not worth the expense of replacing it is madness. Along with the typical lifespan of chillers, their physical condition, reliability, variations in building load and maintenance costs of chillers are some of the factors that need to be weighed.
Only by considering the impact of chiller replacement on these above-mentioned factors is it wise to determine the true value of replacing an existing aged chiller in a facility. For some end users, lower operating costs are a strong motivation for replacing older existing chillers. Here are some clues that will help facility managers and building owners to decide whether they should opt for chiller replacement in their building:
Degradation of Chiller Components
The efficiency of a chiller is entirely tied to the health of its core components: the compressor, evaporator, condenser and expansion valve. As a chiller ages, its components wear out dramatically over time which has a significant impact on the durability and effectiveness of the chiller. Although regular maintenance can prevent some of the effects of aging, performance degrades if not replaced soon.
Frequent Maintenance
All chillers, without exception, necessitate regular maintenance and care to ensure their optimal performance and longevity. As these systems progress through their lifecycle, the demand for maintenance tends to escalate, which is a natural consequence of their continuous operation and the gradual wear and tear of their components. This heightened requirement for upkeep is particularly true for chillers that have been in service for an extended period, as their efficiency and reliability may diminish with age.
In the context of managing these systems from a financial standpoint, it is essential to conduct a thorough analysis of the long-term cost implications. This involves evaluating not only the immediate expenses of maintenance and repairs but also considering the potential downtime due to system failures. When deliberating on the most financially prudent approach to chiller maintenance, one must consider that the frequency and intensity of these activities generally increase as the chiller grows older. In light of these considerations, a strategic evaluation of the chiller replacement option from a cost-effectiveness viewpoint becomes imperative. This analysis should encompass not just the initial investment required for purchasing a new equipment, but also the long-term savings that may be accrued through minimized maintenance costs, and the avoidance of unexpected breakdowns that can result in costly repairs and loss of productivity.
Obsolescence of Components & Parts
One of the major considerations when evaluating the need to replace an existing chiller is the difficulty in obtaining spare parts. Since a chiller is often the most expensive equipment in any facility, it becomes very important to maintain an inventory of its components that wear out over time. Unfortunately, the production of some components of older
chillers may be discontinued, making such parts difficult to obtain.
Refrigerant Regulations and Compatibility
In the dynamic and evolving landscape of the chiller industry, refrigerant regulations are perpetually in a state of flux. These regulations are essential for the environmental sustainability and efficiency of these systems. When examining the multifaceted nature of this decision, one must consider the ever-changing regulatory landscape. Retrofitting, while a seemingly cost-effective short-term solution, involves the modification of existing systems to accommodate new refrigerants.
This process can be complex, potentially requiring significant investment in both time and resources. Moreover, retrofitted systems may still face future challenges as regulations tighten and phase-out periods for certain refrigerants draw near, leading to potential obsolescence and additional costs for further modifications. On the other hand, the installation of a new compliant chiller presents a more holistic approach.
Investing in a new, environmentally friendly chiller not only aligns with current environmental policies but also demonstrates a commitment to sustainability and reduces the long-term operational costs associated with frequent upgrades or replacements. These modern systems often come equipped with advanced technology that enhances energy efficiency, which translates to reduced energy consumption and lower utility bills. Moreover, the performance and reliability of new chillers are generally superior to their retrofitted counterparts, contributing to a more stable and effective temperature control system.
Confronted with the decision between retrofitting outdated chillers with new refrigerants to adhere to the latest environmental standards or opting for a complete upgrade to a modern, compliant model, it becomes apparent that the latter choice holds greater long-term benefits and is inherently more future proof.
Energy Consumption Patterns
Compared to the traditional fixed-speed compressor installed in older existing chillers, a variable-speed operation of the inverter compressor or VFD integrated compressor significantly reduces energy consumption. Inverter technology or VFD based technology is particularly efficient in part load operation while maintaining the desired temperature level. The difference between the specific power consumption of a conventional legacy chiller and a VFD based chiller is intrinsically between 0.3 to 0.4 ikw/TR. Depending on the number of operating hours, energy savings of up to 40% can be achieved.
Provision for Integration with BMS
Building Management System (BMS) is a demand of modern infrastructure as it ensures running of chillers and other systems in synchronization. BMS acts as a dynamic tool to improve operational efficiency as it allows data gathering, auto adjustment of settings in real time, thereby optimizing chiller performance. Older chillers do not have such provisions, so to meet the demands of modern building infrastructure, it is important to select new chillers that are compatible with BMS.
Conclusion
Modern day chillers are available with higher efficiency, and hence lower operating costs. This gives operators more peace of mind. Before venturing into chiller replacement, one needs to gain invaluable insight into chiller longevity, performance and considerations for replacement by recognizing the signs and understanding the intricacies of chiller replacement. Furthermore, the potential benefits of upgrading to a more modern and efficient chiller should be weighed against the ongoing costs of maintaining an aging unit.
When advocating chiller replacement, it is important to conduct a comprehensive life-cycle cost analysis and compare the expense of maintaining the existing chiller against investing in a new one.
Y S Rao holds a degree in Mechanical Engineering and has penned several technical books. With a rich background of 27 years in the HVAC field, he has worked both in India and abroad, notably in Bahrain. He has been designated as a Certified Energy Manager by the Bureau of Energy Efficiency. Rao has imparted his knowledge and insights through numerous lectures to various chapters of ISHRAE and AEE western region focusing on HVAC systems & energy conservation strategies. In addition to his professional engagements, he is also an esteemed instructor on the reputable online educational platform, Udemy.com.
