By Michael Daly, P.E.
From the August 2023 Issue
HVAC systems are critical components of all facilities, providing the necessary indoor climate control for occupants, equipment, and processes. These systems are essential for maintaining a comfortable, controlled, and healthy environment, regulating temperature and humidity levels and preventing the growth of harmful mold and bacteria.
However, as HVAC equipment ages, its performance efficiency will decline, leading to increased energy consumption, higher operating costs, and decreased system reliability. Factors such as wear and tear, lack of maintenance, and the quality of the equipment itself can all contribute to this decline.
Facility managers and building owners are often tasked with finding ways to extend the life of their HVAC equipment and restore lost efficiency. One of the most significant contributors to declining efficiency in aging HVAC systems is oil fouling.
Causes And Effects Of Oil Fouling In HVAC Systems
Oil fouling is a common issue that occurs in HVAC systems. It happens when the lubricating oil in HVAC compressors migrates to the inside surfaces of heat exchanger coils, leaving behind a residual oil film that adheres to the walls of the coils. This residual oil film acts as a thermal insulating barrier, making it harder for the heat exchanger coils to transfer heat effectively and decreasing the overall efficiency of the HVAC system.
The lubricating oil in HVAC compressors serves an essential purpose. It lubricates the moving parts of the compressor, reducing friction and wear. The oil also acts as a seal between mechanical moving parts, limiting the amount of oil and refrigerant interchange. However, over time, some oil will migrate to the inside surfaces of the heat exchanger coils, leaving behind a thin film that gradually accumulates.
In addition to reduced efficiency and increased operating costs, oil fouling can also lead to decreased system reliability and premature equipment failure.
As the residual oil film accumulates, it forms a barrier to efficient heat transfer between the heat exchanger coils and the air or water that flows over them, DX systems or water-cooled chiller systems, respectively. This barrier increases the resistance to heat transfer across the heat exchanger coils, reducing the efficiency of the HVAC system. The system then has to work harder, drawing higher amperes, to achieve the desired temperature, leading to higher energy consumption and operating costs.
In addition to reduced efficiency and increased operating costs, oil fouling can also lead to decreased system reliability and premature equipment failure. An inefficient HVAC system drawing higher amperage and running for more extended periods of time is prone to a shortened life and equipment failure. The reduced life is more than just the compressor as the air handler fan will run longer, also reducing useful life.
Recovering Lost Performance Efficiency With Oil Additives
One of the most effective ways to recover lost performance efficiency in aging HVAC equipment is by using oil additives. Oil additives are chemical compounds added to the lubricating oil in HVAC compressors that displace migrated refrigerant oil adhering to the inside surfaces of the heat exchanger coils, allowing for better heat transfer and restoring lost efficiency.
Oil additives offer several benefits for improving HVAC system efficiency. Firstly, they improve heat transfer by displacing the residual oil film on the heat exchanger coils, allowing them to operate more efficiently. Secondly, they help to prevent the accumulation of sludge and deposits on the heat exchanger coils. Thirdly, oil additives can help to improve the compressor’s reliability and lifespan by reducing mechanical wear and deferring component and system replacement. Consider hermetically sealed DX unit compressors, with the same sump oil resident for the life of the equipment. Inevitably the oil properties diminish with mechanical shear and excessive heat exposure, reducing viscosity. Oil additives also give a boost to the aged original equipment sump oil properties reducing friction, lowering amperage to deliver same BTUs output.
Common Misconceptions And Concerns About Oil Additives
Despite the many benefits of using oil additives in HVAC equipment, there are still some common misconceptions and concerns that facility managers may have about their use.
One common concern about using oil additives is that they may harm the HVAC system or void manufacturer warranties. However, when appropriately used, oil additives are safe for HVAC equipment and will not void warranties. It is essential to work with oil additive suppliers that have qualified product use for each respective refrigerant and refrigerant oil, ensuring products comply with industry standards on compatibility testing and performance verification.
Some facility managers may also be hesitant to use oil additives due to past experiences with additives that were ineffective or caused issues in their HVAC systems. However, advancements in material science have enabled the development in oil additive technology that can be verified as having addressed prior concerns.
Nano-Technology Solutions For Oil Fouling In HVAC Systems
One of the latest advancements in oil fouling prevention is the use of nano-technology solutions. These solutions involve the use of nano-sized particles or molecules that can penetrate surfaces into the heat exchanger coils of HVAC systems to displace residual oil film. The incredibly small size of these particles allows for adherence of a thin film of a highly thermally conductive material that leads to significant gains in system efficiency.
Using nano-technology solutions for oil fouling can offer a more effective and efficient solution for regaining efficiency in heat exchanger coils, resulting in improved HVAC performance and energy savings. Additionally, these solutions can extend the lifespan of HVAC equipment by reducing mechanical wear and deferring component and system replacement.
However, there are also some limitations to consider when using nano-technology solutions for oil fouling. For example, some solutions may not be compatible with certain HVAC system refrigerants or refrigerant oils or may require specialized equipment for application. It is important to ensure that the selected solution is compatible with the specific HVAC equipment and that the application process is performed correctly to achieve optimal results.
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In conclusion, maintaining efficiency in aging HVAC equipment is crucial for the overall performance and sustainability of any facility. The use of oil additives and new nano-technology solutions offers a promising solution for recovering lost efficiency in HVAC systems. Oil additives have proven to be effective in displacing residual oil film in heat exchanger coils, while new nano-technology solutions offer even more effective and efficient solutions. Recovering lost efficiency not only extends the lifespan of HVAC equipment but also reduces operating costs and carbon emissions.
Facility managers should take advantage of these solutions to improve the performance and efficiency of their HVAC systems. Keep in mind the common misconceptions and concerns about oil additives and to ensure that the selected solution is compatible with the specific HVAC equipment. As technology continues to advance, we can expect even more innovative solutions to emerge, further optimizing the performance and sustainability of HVAC systems.
Daly, P.E., Chief Technology Officer at ECM Technologies, is a seasoned professional with 30-plus years of engineering and business management experience. He has made a career of developing, manufacturing and selling lifesaving and life-changing technologies focused on energy conservation measures.
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