Description
The Copeland 3L09-2 is a snap disc limit switch with a 7-1/2 inch capillary, calibrated to open at 240°F and close at 210°F, providing a 30°F differential for controlled high-limit circuit interruption and automatic reset in gas furnaces, boilers, and hydronic heating equipment where reliable overtemperature protection is required. The open-at-240°F set point positions this limit switch within the high-limit range typical of furnace heat exchanger and supply air temperature protection applications, interrupting the burner or heating circuit when the sensed temperature reaches the critical threshold to prevent equipment damage, heat exchanger stress, and unsafe operating conditions. The 30°F differential between the open and close set points establishes a defined temperature recovery band that prevents rapid cycling and ensures the heating system has cooled sufficiently before the limit switch resets and allows the burner circuit to re-energize. The 7-1/2 inch capillary extends the sensing element away from the control body, allowing the disc to be positioned accurately on a heat exchanger surface, duct wall, or equipment panel where direct contact temperature measurement is required. As an OEM-quality Emerson White-Rodgers replacement, the 3L09-2 is a direct-fit service component for furnaces, boilers, and heating equipment that specify a snap disc high-limit control in this temperature and capillary configuration.
Key Features
- Opens at 240°F and closes at 210°F providing a 30°F differential for controlled high-limit circuit interruption and automatic reset
- 7-1/2 inch capillary extends sensing element for accurate positioning on heat exchanger surfaces, duct walls, or equipment panels
- High-limit set point range suited for furnace heat exchanger and supply air overtemperature protection applications
- 30°F differential prevents rapid cycling and ensures adequate equipment cool-down before burner circuit reset
- Automatic reset function restores normal operation once sensed temperature drops below the close set point
- Direct surface contact sensing via capillary element for accurate and responsive high-limit temperature detection
- Snap disc bimetal switching action delivers fast, repeatable circuit interruption without external power or control signals
- OEM-quality Emerson White-Rodgers replacement for furnaces, boilers, and heating equipment specifying this snap disc high-limit configuration
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