EnergiVault extends the life of ALL water chillers by providing unbeatable “AI” controlled load matching!
FACT: Stopping and starting water chillers excessively shortens their lifespan. The extent of the impact varies based on several factors specific to the chiller type and operation.
Impact on Water Chillers
Compressor Stress:
The compressor in a water chiller is one of the most critical and expensive components. Frequent cycling (starting and stopping), known in the industry as “short-cycling”, causes increased wear and tear on the compressor. During starting, drive-motors experience high inrush currents, and compressors are subject to mechanical stresses.
Refrigerant Flow and Pressure:
A compressor during start-up uses up to six times the power it would normally take under full load. During this period, it is not actually refrigerating until the system establishes the correct internal pressures.
Electrical Components:
Starting a chiller involves a significant electrical surge. Repeated electrical surges will shorten the life of electrical components such as contactors and relays.
Cost of Maintenance:
The extra stress on mechanical and electrical components leads to premature wear and increased costly maintenance cycles.
Quantifying the Impact
The exact reduction in lifespan due to frequent stopping and starting is impossible to quantify precisely, but some general observations can be made:
Compressor Lifespan: Frequent starts can reduce the compressor lifespan by 15-30%. This is a rough estimate and can vary depending on the compressor type and method of drive.
Overall System: The overall lifespan of the chiller system is probably reduced by about 15-20% in consideration of multiple additional stresses that “short cycling” places on all components.
Management Strategies
To minimise the negative impacts of frequent starting and stopping, the following strategies can be of assistance:
Soft Starters and VFDs:
Implementing soft starters or variable frequency drives (VFDs) can reduce the initial inrush current and mechanical stress on the compressor.
Advanced Control Systems:
Using advanced control systems to optimise the start-stop cycles can help. For example, implementing control strategies that avoid short cycling by maintaining minimum run times and off times.
Regular Maintenance:
Ensuring regular maintenance and inspections can help identify and address issues caused by frequent cycling before they lead to significant failures.
Proper Sizing:
Ensuring that the chiller is properly sized for the load can reduce the frequency of start-stop cycles. An oversized chiller will cycle more frequently, leading to increased wear.
Load Management:
Implementing load management strategies to ensure the chiller operates under stable load conditions can also help reduce the frequency of cycling.
Thermal Energy Banking:
Using thermal energy banking to supplement periods when the thermal load and chiller capacity sequencing cannot match prevents “short-cycling”.
Stopping and starting water chillers frequently indeed shortens their lifespan, primarily affecting the drive-line and compressor whilst negatively affecting other key components in the system. The extent of the reduced lifespan can be as high as 30% for compressors and about 10-15% for the overall system. Implementing strategies such as soft starters, advanced control systems, regular maintenance, and proper sizing can help mitigate these effects and extend the chiller’s operational life.
The only complete cure, showing economic and mechanical advantages, is thermal battery energy storage. This technology allows complete management of the cooling system, eradicating all the issues discussed above and providing savings during regular operation that redeem the cost of the EnergiVault system in less than three years for some clients and rarely more than five years for others.
