Mars L300-4 Limit Switch, Open on Temp Rise at 300, Auto Close at 260 (39031)

About the Mars L300-4 Limit Switch, Open on Temp Rise at 300, Auto Close at 260 (39031)

Get a bargain on the Mars 39031 300 Limit Switch L300-40 Auto Reset 3/4" while it's still available here at 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 is a popular HVAC brand among both homeowners and contractors for good reason.