If the diastat breaks off a Robertshaw LCC or LCH limit thermostat, how does the control fail?

When the diastat of a Robertshaw LCC or LCH limit thermostat breaks off, the control fails opposite of its normal operation. This means that if the thermostat is designed to open or close a circuit to maintain temperature, the failure will result in a condition where the thermostat no longer fulfills its designed function, typically allowing the equipment to continue operating in an unsafe manner.

Understanding how limit thermostats work is critical. These devices are designed to cut power or signal when a temperature exceeds a set limit, ensuring safe operation. If the diastat breaks, it disrupts this function, and the system may continue operating even when it shouldn't, which is contrary to normal operation where it would normally shut off to prevent overheating. Hence, this characteristic is why the control fails in a manner opposite to its intended purpose, leading to potentially hazardous conditions.

The other failure modes mentioned do not accurately reflect the operational characteristics of limit thermostats; hence, they do not represent the actual working conditions of a broken diastat as effectively as this choice.