In a heating system, a limit control serves what purpose as long as the plenum temperature stays below its set point?

The function of a limit control in a heating system is to monitor the temperature of the plenum, which is the area where air is distributed throughout the building. When the plenum temperature is below the set point, the limit control remains closed, thereby allowing the heating system to continue operating freely. This closure ensures that the system maintains efficient heating without unnecessary interruptions, promoting consistent and effective temperature regulation within the space.

In contrast, if the temperature were to exceed the set point, the limit control would open, shutting down the heating system to prevent overheating and potential damage. This safety feature is crucial for protecting both the heating system and the environment in which it operates.