Which condition can lead to the temperature limit safety switch shutting off the burner?

The temperature limit safety switch is a critical component of a gas furnace, designed to prevent overheating and protect the unit from potential damage or dangerous conditions. When the temperature within the heat exchanger or furnace itself exceeds a predetermined limit, the switch triggers and shuts off the burner to prevent further heating.

In the scenario presented, if the fan motor fails, it can no longer effectively circulate air through the furnace. This failure leads to a situation where the heat produced by the burner cannot dissipate properly. As a result, the temperature within the furnace will rise rapidly, potentially exceeding safe levels. Consequently, the temperature limit safety switch is activated to shut down the burner, ensuring the system does not overheat and potentially creates a hazardous situation.

Other factors, such as overheating of the furnace, are generally a consequence of fan failure or other issues rather than direct triggers for the safety switch initiation. While a gas leak detection system is critical for safety, its role is to ensure that harmful gas doesn’t accumulate, rather than directly causing the limit switch to activate. Lastly, a faulty thermostat may lead to erratic heating, but it typically does not directly cause the temperature limit safety switch to engage if overheating is not an issue. Understanding these relationships highlights the importance of the fan