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1/2″ vs. 3/4″ Bi-metal Disc

You may be wondering the difference in 1/2″ and a 3/4″ bi-metal Disc besides just the size. There are are more features that change when you go up or down in size. View the Senasys line of Bi-metal Discs.

The size of the switch is actually referring to the size of the bi-metal disc used, not the size of the switch assembly. A ¾’’ switch is actually about twice the size of a ½’’ switch.

15 Amp Auto Reset Thermostat Switches½’’ and ¾’’ switches function the same, but there are a few key differences in how they can be used.

  • ½’’ switches are smaller, so they are good for applications where space is limited.
  • 3/4’’ switches have more surface area on the disc, so they are slightly more accurate in sensing temperature.
  • If an application requires a tighter tolerance, a ¾’’ switch would be the better option.¾’’ switches also have a higher electrical rating. For example our 430 line of ½’’ switches has a rating of 15 amps at 120 VAC, while our 2511 line of ¾’’ switches has a rating of 25 amps at 240

1/2″ and 3/4″ Bi-metal Disc Descriptions

1/2″ Bi-metal Options 

15 AMPS 430 Series 430 Loose Hold Mount Thermostat Switch

The 430 Series is our 1/2″ automatic reset snap disc. These switches have a smaller footprint than the 2511 Series automatic reset thermostat switches, allowing for a lower cost. These switches are available in a single-pole, single-throw device, rated up to 15 Amps at 120VAC. The 430 snap disc thermostat switches have a temperature range of 35-350°F (2-175°C), with a differential temperature range of 15-100°F (-9-

15 AMPS – 2570/431 Series (SPST) 431 Epoxy Sealed Pipe Mount Thermal Switch

These sealed thermal switches are highly versatile, carrying up to 15 Amps at 120VAC, are available SPST. The bimetal thermodisc within is set to a precise temperature range between -40°-220°F (-25°-105°C).

3/4″ Bi-metal Options 

25 AMPS 2511 Series2511 Notched Bracket Automatic Reset Thermal Switch - Notched Bracket

These robust thermostat switches 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″ bimetal thermodisc at the heart of our thermostat is set to a precise temperature range within 0-350°F (-18-176°C).



These sealed thermal switches are highly versatile, carrying up to 10 Amps at 120VAC, are available as a SPDT thermostat switch. The 3/4″ bimetal thermodisc within is set to a precise temperature range between -20-220°F (-25-105°C). These switches are not available to view or purchase online. Please contact us with your requirements.

Contact Us SenasysPurchase at Senasys

Want more information on our Bi-metal Discs? Check out the links below!

Manual Reset or Automatic Reset 

When to use Gold Plated Electrical Contacts

Snap Disc Quick Connect vs. Screw Terminals 

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