Which low-pressure control is responsible for shutting down the oil burner when there is insufficient air for combustion?

The vaporstat is a critical component designed to monitor the amount of air in the combustion chamber and ensure that there is an adequate supply for proper operation of the oil burner. When there is insufficient air, which can lead to incomplete combustion and potential safety hazards such as carbon monoxide production, the vaporstat will activate and shut down the burner. This safety mechanism is essential in maintaining safe operating conditions and preventing potential risks associated with improper combustion.

In contrast, a thermostat primarily regulates temperature by controlling when the burner should operate based on the ambient temperature, but it does not monitor air supply. A pressure switch is designed to detect and respond to pressure levels, typically concerning the fuel or water pressure, rather than the air-to-fuel ratio necessary for combustion. A flow switch monitors the flow of fuel or air but does not specifically address the air requirements for the burner operation. Thus, the vaporstat is specifically responsible for managing safe combustion conditions related to air supply, making it the correct choice for this question.