Snap Action Thermostat

The snap action units are round in construction (approx 5/8” dia.) due to the bimetal disk that provides the snap action. The disk is shaped similar to a contact lens and snaps back and forth at pre-set temperature to make and break the contact points. The pros and cons of these types of units are:

 

Due to the energy required to snap the disk over center, the temperature differential between on and off is 20° to 30°F.  When used as a high limit over 300°F this differential can be as large as 75°F. Maximum temperature for high limit is 500°F.

The wide differential does not provide narrow band temperature control but also does not generate any radio frequency interference due to the positive make/break action.

The most common use for these units is freeze protection and enclosure control with a setting of On at 40°F / Off at 60°F.

These units must be covered with an overmold that is bonded to the heater.

 

Creep Action Thermostat

Temperature Sensors

Thermal Fuses

Thermocouples

Resistance Temperature Device (RTD)