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As your trusted source for a wide variety of thermal control products, Comstat carries a diverse selection of mechanical and electronic thermostats including:

  • Bimetal thermostats
  • Adjustable thermostats
  • Precision thermostats
  • Probe Style
  • Electronic thermostats
  • Snap Disc or switch thermostats
  • Elmwood and Honeywell Redi-Temp
  • Control thermostats

Comstat maintains diverse assortment of in-stock standard products, including switch thermostats and bimetal thermostats. This allows us to ship most orders immediately and with a low $50 minimum order. If you are an OEM in need of a custom thermostat, check out our Thermostat Design Configurator or contact us to speak directly with a member of the highly knowledgeable Comstat team.

What is a thermostat and how do they work?

Thermostats are temperature-sensitive components used to either maintain the operating temperature of a system or to break an electrical connection should a system’s temperature deviate from its desired range. The thermostat accomplishes this by switching heating or cooling devices on or off, or by regulating the flow of heat transfer fluid as needed. Thermostats are often essential for controlling the functionality of a system and for preventing damage while ensuring safety.

Thermostats are either mechanical or electronic. Mechanical Snap Disc or switch thermostats are by far the most common thermostat used in applications ranging from complex industrial machinery to controlling simple commercial appliances and HVAC systems. The Snap Disc thermostat is mounted directly on the surface of the device being controlled. It mechanically makes and breaks a contact that switches the power supply of a heating or cooling device on or off automatically as the temperature rises and falls. Electronic thermostats differ mainly in that they are usually mounted remotely and their temperature inputs are provided by separate temperature sensors, such as thermocouples, RTDs, and thermistors, rather than an internal bimetal component. Electronic thermostats also often have displays for visual monitoring of the process temperature.

Snap Action Thermostats to fit any Application

Snap Disc, or snap action thermostats are ideal in a wide variety of applications because they are highly versatile and customizable. Comstat offers the following options for Snap Disc thermostats and related snap switch products:

  • Models with operating temperature ranges from -45C to +425C
  • Models with tight differentials for temperature control
  • Gold contacts for very low current applications
  • Special tolerances depending on need
  • Various mounting and termination options
  • Encapsulated models for protection to IP64
  • Precision and commercial models
  • Hermetic or non-hermetic seals
  • Automatic or manual reset options                         
  • Honeywell Redi-Temp and Redi-temp compatible models available                               

Many of these snap action thermostat options are available as in stock standard products and are ready to ship. Browse our inventory below or visit our Thermostat Design Configurator to find the right Snap Disc thermostat for your project!

What is a snap switch also known as Snap Disc or snap action thermostat?

Snap Disc, or snap switch thermostats are bimetal mechanical thermostats that function via the thermal expansion and contraction of a bimetal disc that “snaps” from a convex to a concave shape at a set temperature. When the disc “snaps”, it either completes or interrupts a circuit. Snap Disc thermostats have many practical applications. They are used in both heating and cooling applications to ensure the process temperatures do not exceed the thermal limits of the equipment or process. In some cases, Snap Disc thermostats with tight differential models can be used as the primary temperature control device. However, the most common application for a snap switch or snap action thermostat is as an over-temperature protection (or OTP) failsafe.

Because of their small size and low mass, the response time of the snap switch design is extremely rapid compared to other commercially available thermostatic devices. Additionally, the bimetal element of a Snap Disc does not carry the current, but acts as the force to open and close the contacts. Thus snap action thermostats have a long life at relatively high currents – up to 16 amps for the ½ inch series – making snap switches the first choice of many OEMs.

Precision Snap Disc thermostats are found in commercial food equipment, adhesive dispensing devices, laboratory instrumentation, aircrafts, medical equipment, electronic control systems and more. Commercial Snap Disc thermostats are most commonly found in appliances, heat and smoke detectors and HVAC equipment.

Comstat offers the following standard types of these bimetal snap switch thermostats: automatic reset Snap Disc thermostats; manual reset Snap Disc thermostats, and adjustable Snap Disc thermostats. Comstat also offers the widest possible operating temperature ranges for bimetal thermostats, ranging from -45C to +425C.

Want to know more about Comstat’s selection of snap action thermostats? Download Comstat’s Snap Disc Thermostat Primer PDF for more technical and application information, or contact us to speak directly with a member of the highly knowledgeable Comstat team.


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