Mars L140-4 Limit Switch, Open on Temp Rise at 140, Auto Close at 100 (39018)

About the Mars L140-4 Limit Switch, Open on Temp Rise at 140, Auto Close at 100 (39018)

Shop the Mars 39018 140 Limit Switch L140-40 Auto Reset 3/4" from PlumbersStock.com. Limit switches are sensors that detect when a furnace has exceeded operational temperature limits and shut the appliance down as a safety measure. The way it works is that if your temperature gets to a concerning level, the limit switch will automatically open the circuit so it shuts off. It will remain off until the switch automatically closes the circuit when the temperature reaches the off threshold. Mars products will last you a long time, but parts will wear, and you can find replacements here when they do.