3/4″ Manual Reset Snap Disc Thermostats

Senasys manufactures 3/4″ Manual Reset Snap Disc Thermostats, 404 series. Our manual reset thermostat switches are ideal when you want to call special attention to a temperature malfunction. Because the switch needs to be manually reset, a human must interact with the switch and solve the problem before the equipment or appliance can work again.


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


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


All of our snap disc units are UL approved (USR).


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

The 404 series is our 3/4″ manual reset snap disc. This series is ideally suited for applications where you want to call special attention to a specific temperature malfunction. The 404 series feature a trip-free operation. Physical depression of the reset button holds the contact open and renders the device inoperative until the reset button is released.

Our 404 manual reset snap disc thermostats have a temperature range of 100-350°F, ±25°F. Many standard temperature options are available, or we can easily design a customer temperature range to suit your application requirement.

Product Specifications

  • 3/4″ Bi-Metal Snap Action Disc
  • Manual Reset
  • Breaks on temperature rise
  • SPST (Single Pole, Single Throw)
  • 25 Amps @ 120VAC, 6,000+ cycles
  • Temperature Range of 100°-350°F, ±25°F differential
  • Available with exposed caps to provide a faster response time.
  • Special black discs can be used to further improve the response to radiative heating in exposed units.
  • Available with a variety of mounting brackets
  • Variety of terminal options available.
  • UL Listed
  • Made in U.S.A.

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.

Standard Direct Mount
Electric Heat Direct Mount
Notched Bracket Surface Mount
Large Surface Mount
Small Flange Surface Mount
Airstream Mount

Terminal Options

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
Electric Heat Terminals

Standard Temperature Options

Below is a list of our common, off the shelf, bi-metal temperature options.

Custom temperature options available. Please contact us.

Disc Number


Open 120°F ±5°F


Open 150°F ±5°F


Open 190°F ±5°F


Open 200°F ±7°F


Open 225°F ±7°F


Open 250°F ±8°F


Open 300°F ±8°F


Open 350° ±8°F

Common Applications

Our 3/4″ manual 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
Other Custom

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.

Cross Reference

We are certain of our position at the top so we’re comparing our product with other top products in the marketplace today.

Find further details by visiting this link.


404 Series


60T Series


SE/SES Series

3/4″ Bi-Metal Disc

Enclosed or Exposed

Manual Reset
Fixed Temperature 100°F to 350°F

Open on Temp Rise

Single Pole, Single Throw


25 Amps @ 120VAC

+6,000 cycles

Variety of Mounting Options
Variety of Terminal Options
UL Listed
Made in U.S.A.

Build A Thermostat

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

Request A Quote

Complete the form below with your application information, and a product specialist with follow up with you in 1-2 business days.

    Your Name (required)

    Your Company

    Your Email (required)

    Telephone Number (required)


    Your Message