Mechanical

System Failures

Commercial Water Heater Explosion

Mechanical System Failures

Commercial Water Heater Explosion

Mechanical System Failures

Commercial Water Heater Explosion

A commercial water heater at a South Carolina school exploded as a maintenance worker stood in the doorway to the mechanical room.  The blast sent the worker backward and he collided with his vehicle parked nearby.  The maintenance worker sustained various injuries as a result of the incident.

Mechanical Room Entrance

The EIS engineer assigned to the project interviewed other maintenance workers familiar with the incident and the equipment.  They explained that there were two water heaters in the subject mechanical room.  Both water heaters were installed three years earlier during construction of an addition to the school.  The subject water heater began operating poorly after the first year.  Specifically, the unit would regularly trip a safety switch and shut down.  The maintenance workers were frequently onsite to reset the problem water heater, which was the reason the injured worker was onsite at the time of the incident.

Remaining Water Heater with Wrong Burner Section Visually Similar to the Subject Unit

During the site inspection, the EIS engineer observed that the burner sections of the two water heaters of the mechanical room were swapped.  The burner that was installed in the subject water heater was significantly oversize and not designed to be used with the heat exchanger it was paired with.  Inspection of the internal components revealed that the burner nozzle and flame cone were deteriorated in a manner not attributable to an explosion.

Flame Cone Deteriorated and Damaged by the Blast

Through further inspection and analysis, it was determined that the combustion chamber was too short for use with the oversized burner.  The length of the burner flame exceeded the length of the combustion chamber and the flame was hitting the back wall or tube sheet of the heat exchanger, overheating the combustion chamber and burner components.  Over time, the burner nozzle and flame cone deteriorated due to the excessive heat.  With the damaged components, the burner could not achieve a steady flame or complete burning of the fuel gas.  It was determined that the unburned gas had built-up in the combustion chamber and was not purged before the burner relit when the system called for heat.  The built-up gas in the combustion chamber ignited, resulting in the explosion.

A commercial water heater at a South Carolina school exploded as a maintenance worker stood in the doorway to the mechanical room.  The blast sent the worker backward and he collided with his vehicle parked nearby.  The maintenance worker sustained various injuries as a result of the incident. 

Mechanical Room Entrance

The EIS engineer assigned to the project interviewed other maintenance workers familiar with the incident and the equipment.  They explained that there were two water heaters in the subject mechanical room.  Both water heaters were installed three years earlier during construction of an addition to the school.  The subject water heater began operating poorly after the first year.  Specifically, the unit would regularly trip a safety switch and shut down.  The maintenance workers were frequently onsite to reset the problem water heater, which was the reason the injured worker was onsite at the time of the incident.

Remaining Water Heater with Wrong Burner Section Visually Similar to the Subject Unit

 

During the site inspection, the EIS engineer observed that the burner sections of the two water heaters of the mechanical room were swapped.  The burner that was installed in the subject water heater was significantly oversize and not designed to be used with the heat exchanger it was paired with.  Inspection of the internal components revealed that the burner nozzle and flame cone were deteriorated in a manner not attributable to an explosion.

Flame Cone Deteriorated & Damage by the Blast

Through further inspection and analysis, it was determined that the combustion chamber was too short for use with the oversized burner.  The length of the burner flame exceeded the length of the combustion chamber and the flame was hitting the back wall or tube sheet of the heat exchanger, overheating the combustion chamber and burner components.  Over time, the burner nozzle and flame cone deteriorated due to the excessive heat.  With the damaged components, the burner could not achieve a steady flame or complete burning of the fuel gas.  It was determined that the unburned gas had built-up in the combustion chamber and was not purged before the burner relit when the system called for heat.  The built-up gas in the combustion chamber ignited, resulting in the explosion.    

A commercial water heater at a South Carolina school exploded as a maintenance worker stood in the doorway to the mechanical room.  The blast sent the worker backward and he collided with his vehicle parked nearby.  The maintenance worker sustained various injuries as a result of the incident. 

Mechanical Room Entrance

The EIS engineer assigned to the project interviewed other maintenance workers familiar with the incident and the equipment.  They explained that there were two water heaters in the subject mechanical room.  Both water heaters were installed three years earlier during construction of an addition to the school.  The subject water heater began operating poorly after the first year.  Specifically, the unit would regularly trip a safety switch and shut down.  The maintenance workers were frequently onsite to reset the problem water heater, which was the reason the injured worker was onsite at the time of the incident.

Remaining Water Heater with Wrong Burner Section Visually Similar to the Subject Unit

During the site inspection, the EIS engineer observed that the burner sections of the two water heaters of the mechanical room were swapped.  The burner that was installed in the subject water heater was significantly oversize and not designed to be used with the heat exchanger it was paired with.  Inspection of the internal components revealed that the burner nozzle and flame cone were deteriorated in a manner not attributable to an explosion.

Flame Cone Deteriorated and Damage by the Blast

Through further inspection and analysis, it was determined that the combustion chamber was too short for use with the oversized burner.  The length of the burner flame exceeded the length of the combustion chamber and the flame was hitting the back wall or tube sheet of the heat exchanger, overheating the combustion chamber and burner components.  Over time, the burner nozzle and flame cone deteriorated due to the excessive heat.  With the damaged components, the burner could not achieve a steady flame or complete burning of the fuel gas.  It was determined that the unburned gas had built-up in the combustion chamber and was not purged before the burner relit when the system called for heat.  The built-up gas in the combustion chamber ignited, resulting in the explosion.