3/4″ Automatic Reset Snap Disc Thermostats

Our 3/4″ Automatic Reset Snap Disc Thermostats (2511 series) are great for unique applications which require a faster response time or a lower contact resistance.

These robust 3/4″ Automatic Reset Snap Disc Thermostats can be used in high current applications; carrying up to 25 amps at 240VAC, for over 100,000 cycles (30 Amps at 12VDC for 30,000 cycles). These switches are available in a single-pole, single-throw device.

A 3/4″ automatic reset snap disc at the heart of our thermostats are set to a precise temperature range within 0-350°F (-18-176°C). The temperature range determines when the thermal switch will close, or engage the electrical circuit, and when it will automatically reset, or open.

custom options

Designed & manufactured to meet requirements of original equipment manufacturers worldwide.

high quality

Senasys products are 100% tested before they leave our facilities.


All of our snap disc units are UL approved (USR) and the 2511 family is also Canadian Standard approved (CNR).

made in u.s.a.

Designed & manufactured in Eau Claire, WI, U.S.A.

Senasys 2500 Series Thermostats are quality-engineered thermal sensors specifically designed for a variety of major appliances, including clothes dryers, hot liquid and food-dispensing machines, room unit and space heaters, air conditioning systems, copy machines, engine heaters, and wood stoves. Made to open or close on a temperature rise, the 3/4” Thermostat is rated at 25 AMPS-240 Volts, meets UL Standards 873 and 353 and is available in a single-pole, single-throw device. Temperature calibrations are preset, and all units are subject to 100% mechanical and thermal inspection. To insure that a safe combination of thermostat and application is achieved, the purchaser must determine product suitability for their individual requirements.

Product Specifications

  • 3/4″ Bi-Metal Snap Action Disc
  • Automatic Reset
  • Breaks on temperature rise or fall
  • Single Pole, Single Throw (SPST)
  • Rated Up To 25 Amps @ 120VAC, 100,000+ cycle life
  • 0°F to 350°F Temperature Range
  • Gold Contacts Available for Low Current & Voltage Applications
  • Bi-Metal is available enclosed, or exposed for a faster reaction time.
  • Multiple mounting options such as pipe mounts & stud mounts
  • Multiple terminal configurations
  • UL Listed
  • Made in U.S.A.

For low current and voltage applications gold contacts are available. These provide lower contact resistance and provide better performance for electronic duty loads. With gold contacts this switch becomes and effective tool for applications using milliamp and/or millivolt signals. The gold contacts have a lower contact resistance and provide a better signal quality then the high current silver contacts.

Exposed disc caps are available to provide a quicker response to temperature changes. Special black discs can be used to further improve the response to radiative heating in exposed units.

For a more economical solution, Senasys has built relationships with overseas suppliers to provide our customers thermostats at a lower cost, with the same high quality as our snap disc thermostats built in the U.S.A.

Mounting Options

Select from a variety of mounting options below.

B501 Small Flange Direct Mount
B502 Large Flange Airstream Mount
B504 Large Flange Bracket Mount
B507 Notched Bracket, Surface Mount

Terminal Options

Our 2511 series is available with a variety of terminal options. Our standard terminals are 1/4″ Quick Connect Terminals or Screw Terminals.

A variety of terminal bends & orientations are also available. Our standard terminal bends are 0°, 45° or 90°.

Learn more about our terminal options available  here.

For other custom options, please  contact us.

1/4″ Quick Connect Terminals
Screw Terminals

Standard Temperatures

Below is a list of our common, off the shelf, bi-metal temperature options. Custom temperature options available. Please contact us.

The close on rise thermal switch will engage the electrical circuit (close) when temperature increases, and will automatically reset (open) when temperature falls.

Disc Number


Close at 15°F (±3°F) Open at 5°F (±3°)


Close at 35°F (max) Open at 25°F (min)


Close at 45°F (±5°F) Open at 34°F (±5°)


Close at 50°F (±5°F) Open at 40°F (±5°)


Close at 65°F (±5°F) Open at 50°F (±5°)


Close at 70°F (±5°F) Open at 60°F (±5°)


Close at 80°F (±5°F) Open at 65°F (±5°)


Close at 90°F (±5°F) Open at 80°F (±5°)


Close at 100°F (max) Open at 85°F (min)


Close at 110°F (±5°F) Open at 95°F (±5°F) 


Close at 120°F (±5°F) Open at 105°F (±5°F) 


Close at 130°F (±5°F) Open at 115°F (±5°F) 


Close at 140°F (±5°F) Open at 110°F (±5°F) 


Close at 150°F (±5°F) Open at 135°F (±5°F) 


Close at 160°F (±5°F) Open at 145°F (±5°F) 


Close at 170°F (±5°F) Open at 155°F (±5°F) 


Close at 180°F (±5°F) Open at 165°F (±5°F) 


Close at 190°F (±5°F) Open at 175°F (±5°F) 


Close at 200°F (±5°F) Open at 185°F (±5°F) 


Close at 220°F (±5°F) Open at 200°F (±5°F) 


Close at 230°F (±5°F) Open at 200°F (±5°F) 


Close at 250°F (±6°F) Open at 230°F (±5°F) 


Close at 300°F (±10°F) Open at 260°F (±7°F) 


Close at 325°F (±12°F) Open at 275°F (±8°F) 

The open on rise thermal switch will release the electrical circuit (open) when temperature increases, and will automatically reset (close) when temperature falls.

Disc Number


Open at 15°F (±5°F) Close at 5°F (±5°F)


Open at 30°F (max) Close at 20°F (min)


Open at 40°F (max) Close at 30°F (min)


Open at 45°F (max) Close at 35°F (min)


Open at 50°F (±5°F) Close at 40°F (±5°F)


Open at 60°F (±5°F) Close at 50°F (±5°F)


Open at 70°F (±5°F) Close at 60°F (±5°F)


Open at 95°F (±5°F) Close at 85°F (±5°F)


Open at 100°F (±5°F) Close at 85°F (±5°F)


Open at 110°F (±5°F) Close at 100°F (±5°F)


Open at 120°F (±5°F) Close at 110°F (±5°F)


Open at 130°F (±5°F) Close at 120°F (±5°F)


Open at 140°F (±5°F) Close at 125°F (±5°F)


Open at 150°F (±5°F) Close at 140°F (±5°F)


Open at 160°F (±5°F) Close at 150°F (±5°F)


Open at 170°F (±5°F) Close at 160°F (±5°F)


Open at 180°F (±5°F) Close at 170°F (±5°F)


Open at 190°F (±5°F) Close at 180°F (±5°F)


Open at 200°F (±5°F) Close at 185°F (±5°F)


Open at 220°F (±5°F) Close at 205°F (±5°F)


Open at 245°F (±5°F) Close at 205°F (±5°F)


Open at 260°F (±5°F) Close at 240°F (±5°F)


Open at 280°F (±5°F) Close at 260°F (±5°F)


Open at 302°F (±5°F) Close at 280°F (±5°F)


Open at 325°F (±5°F) Close at 300°F (±5°F)

Common Applications

Our 3/4″ automatic reset snap disc thermostats are found in a variety of applications. Choose a category below to learn more.

Automatic Reset Thermostat Switch Controls Food Equipment
Food Equipment
Snap Disc Thermostat Controls Generator
FASTON Terminal Connectors
Other Appliances

Frequently Asked Questions


When should an exposed snap disc cap be used?

One of the standout characteristics of an exposed cap is its’ use of a black exposed disc. This disc serves as a crucial element in sensing temperature fluctuations swiftly, enabling the switch to respond rapidly to environmental changes. This quick thermal response is especially important in applications where precise temperature control is paramount, such as in thermostats, industrial control systems, and appliances. The exposed caps are available for all non-epoxied snap disc thermostats within the Senasys catalog. 

For more information on exposed snap disc caps, click  here

When should gold contacts be used in place of silver?

One of the key advantages of gold contacts is their significantly lower contact resistance when compared to high-current silver contacts. This low resistance translates into improved electrical conductivity, allowing for smoother and more reliable signal transmission. This is especially important in applications where even the slightest interruption or distortion in the signal could lead to critical errors or malfunctions.

For more information on when gold contacts should be used, click here.

What is a flange mount?

When it comes to temperature monitoring, precision is key. The standard flange mount plays a vital role in achieving this precision by minimizing the distance between the sensor and the area being measured. This reduced gap ensures that temperature fluctuations are detected and recorded with remarkable accuracy, making it an indispensable tool in industries where temperature control is critical.

For more information on flange mounted snap disc thermostats, click  here

What custom temperatures are available?

For small quantities, we can build anything from 0°F to 350°F. Contact us for higher temperatures.

How much power does a snap disc use?

A snap disc does not use any power. Instead it acts as a circuit breaker for a system.

What material are 3/4” snap discs made from?

The body of the switch is plastic, and the mounting cap is steel.

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2511 Series


60T Series


SE / SES Series

3/4″ Bimetal Disc
Automatic Reset
Fixed Temperature
0°F to 350°F
Single Pole, Single Throw


25 Amps @ 240VAC

100,000 cycles

Variety of Surface & Airstream Mounting Options
Variety of Terminal Options
UL / cUL Listed
Made in U.S.A.

Build Your Thermostat

Follow the below nomenclature guide to determine the 3/4″ automatic reset thermostat to meet your application requirements.

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