Which condition would trigger a temperature limit safety switch to shut off the burner?

The condition that would trigger a temperature limit safety switch to shut off the burner is related to potential overheating of the system, which could result from a fan motor failure. When a fan motor fails, it may no longer be able to properly circulate air or exhaust gases. This inadequate circulation can cause excessive heat buildup within the heating system, triggering the temperature limit safety switch. The purpose of this switch is to prevent damage to the system and ensure safe operation by shutting down the burner if the temperature exceeds a certain threshold.

In heating systems, maintaining the right balance of airflow is critical for efficient operation and safety. If the fan is not functioning correctly due to motor failure, there is a risk that the heat generated by the burner will not be effectively dissipated, leading to hazardous conditions. Therefore, the temperature limit safety switch acts as a safeguard to prevent the potential dangers associated with overheating.

The other conditions may impact the operation or performance of the system, but they do not directly relate to temperature control in the same immediate and critical manner as a fan motor failure does.