Which component is necessary for a pneumatic thermostat to control an electric strip heater?

To control an electric strip heater using a pneumatic thermostat, the necessary component is a relay switch. A relay switch acts as an intermediary that allows the low-power signal from the pneumatic thermostat to control the high-power circuit required for the electric strip heater operation.

The pneumatic thermostat itself does not provide enough power to turn the heater on and off directly, hence the need for a relay. The relay switch is designed to handle the higher voltage and current associated with the strip heater, allowing safe and efficient operation.

While a transformer converts voltage levels and a contactor is used for heavy-duty switching, the relay switch specifically fits the scenario where low power from the thermostat needs to control a higher power load, making it the essential component in this application.