During a recent heatwave, MSC received an urgent emergency call from a facility manager at a plant where we provide scheduled HVAC preventive maintenance. A dryer room was overheating and working conditions inside had become dangerously hot.
Another mechanical contractor that had done repair work on the system was originally contacted about the problem. However, due to an influx of heatwave-related emergency calls, it would be hours before they could respond. Unable to wait, the facility manager turned to MSC and fortunately we were able to dispatch one of our senior HVAC technicians right away.
The HVAC system serving the room was a once-through 100% outside air system with several make-up units and associated dryer exhaust fans. With an outdoor temperature of 97°F, temperatures inside the room typically would reach 98-99°F due to added dryer heat. However, the room temperature was 112°F when the call was made and still rising. Dryer room workers were taking frequent breaks to keep the process running until the issue could be fixed, but if temperatures weren’t brought under control soon, the process would have to be shut down. Another concern was that sensitive electrical devices would begin to fail in the extreme heat.
Our technician arrived on the scene at around 4:30 p.m. and made his way to the roof to check the make-up air handling units. He quickly discovered that the outside air dampers’ mechanical linkage had come apart on two of the machines and the only damper still open was one coupled directly to the large Belimo motor. Fortunately, all of the detached parts were found lying in the ductwork, so no additional parts were needed to reconnect the linkage that had apparently loosened and come apart over time. Within a short time, the linkage was reassembled and full airflow was again being provided.
Next, the technician examined the exhaust systems and discovered a large accumulation of dirt and debris partially blocking the exhaust plenum ductwork leading into the fans. Several plant workers were enlisted to assist with removing the debris over the next hour. With both fixes applied, full airflow and air changes were restored to the dryer room.
When our technician departed around 7:00 p.m., it was 82°F outside and the dryer room temperature had dropped to 84°F. With the heatwave expected to continue for several more days, this came as a huge relief to the facility manager and plant owners.
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