How does Bimetal Work?

If you’ve looked at temperature switches before, you’ve most likely heard the term “Bimetal”. But what does that mean? Well, I’m glad you asked. The way Bimetal works is that two different types of metal are fused together. The two metals have different coefficients of thermal expansion, which basically means that they expand at different rates when they heat up. In the case of our switches, the bimetal is in a coil, and the expansion and contraction of the coil is what causes the switch to trigger and open the contacts.

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The Duct High Temperature Switches feature a helix bimetal element that senses rapid increases in duct temperature, such as those caused by fire. The high temperature limit then operates an SPST switch that opens with a rise in temperature. A manual reset button reactivates the temperature limit after the high-temperature condition has cleared. These duct high temperature limits are indispensable in specialized HVAC applications and Building Automation Systems.

Bimetal thermostats are commonly used because of how versatile and robust they are. They can sense a wide range of temperatures and last a long time. They are also entirely physics based, so they do not draw power or require any sort of software.


If you want to learn more about bimetal and the specifics on how it works, check out this great website.

As always, if you have any questions, be sure to contact us.

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