Emerson Climate Technologies
Emerson 3L03-140 Snap Disc Limit Control 120/140°F hvac control
Snap disc limit control with SPDT switching for high-limit safety regulation, opening on rise at 140°F and cutting in at 120°F
- High-limit safety regulation prevents overheating
- SPDT switching provides reliable circuit control
- Manual reset ensures deliberate restart after trip
- Open-on-rise at 140°F protects equipment
- Cut-in at 120°F maintains stable operation
HVAC high-limit safety control
The Emerson 3L03-140 Snap Disc Limit Control provides high-limit safety regulation for heating and cooling equipment. It uses a snap-disc mechanism to switch automatically when temperature thresholds are reached. The SPDT configuration offers flexible wiring for various control circuits. This device suits technicians and installers maintaining forced-air systems.
Sustained temperature cycling performance
Under continuous operation the control reliably opens on temperature rise at 140 degree F and closes again on fall at 120 degree F. The snap-action disc resists contact welding during repeated cycles. Manual reset ensures the circuit stays open until a technician confirms safe conditions. Flanged airstream mounting keeps the sensing element directly in the airflow for consistent response.
Replaces fixed-limit or auto-reset controls
This control upgrades installations that previously used non-adjustable fixed-limit switches or automatic-reset models. The manual-reset function adds a deliberate safety step after an over-temperature event. The SPDT contacts allow both alarm signalling and equipment shutdown from one device. The 120/140 degree F range fits standard residential and light-commercial furnace limits.
Highlights
- High-limit safety regulation prevents overheating
- SPDT switching provides reliable circuit control
- Manual reset ensures deliberate restart after trip
- Open-on-rise at 140°F protects equipment
- Cut-in at 120°F maintains stable operation
Specifications
| Brand | Emerson |
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Questions about this item
How much heat does the Emerson 3L03-140 generate when running continuously?
This limit control is a passive safety switch with no internal heater or motor, so it adds no measurable heat to the system while monitoring temperature.
What existing wiring or mounting hardware is required to install this SPDT limit control?
It requires a standard flanged airstream mounting location and connection to the three SPDT terminals for the control circuit.
Will the 120 °F cut-in and 140 °F cut-out points work with older furnaces that use similar snap-disc controls?
Yes, the fixed 120 °F cut-in and 140 °F cut-out temperatures match common high-limit ranges used in many legacy heating systems.
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