Coachair performed a pre-overhaul inspection of an ageing fleet of HVACs for a metropolitan rail operator. We established that the unit did not need another overhaul as they were in excellent operational condition. However, upon further investigation, Coachair discovered that this fleet had over 2,000 reported faults annually. Over 50% of these faults were No Fault Found (NFF), and a further 30% were resets with Not Known Fault.
We identified a high potential for the units to present with an NFF if the return air filters were blocked. The blockage meant the unit was operating at reduced capacity (potentially causing out of temperature faults) or lower system pressures (resulting in low-pressure faults).
The Coachair solution:
Coachair’s solution was to develop a drop-in frame and design a high efficiency and extended surface area filter solution. This solution provides multiple long-term benefits:
- Increased airflow in all operating conditions, thereby increasing the unit’s cooling capacity.
- Increased system efficiencies which reduced power consumption for the same cooling output.
- Increased filter face area significantly lengthened the servicing intervals, resulting in reduced costs, and allowing alternate maintenance scheduling.
- Increasing system pressures, thereby reducing LP faults that lead to NFF.
