STS Thermal SystemsSTS Thermal Systems
STS Thermal Systems

Flexible Heaters - Thermostats & Thermal Fuses

Fax-Back Data Sheet

Heaters can be fabricated with thermostats, thermal fuses, thermocouples and resistance temperature detectors (RTD) as an integral part of the heater.

Temperature Sensors
Sensors can be located to monitor either heater surface or part temperature. Small sensors are held in place with a protective cover of silicone rubber/fiberglass vulcanized to the heater body. Larger sensors and thermostats have a protective cover (overmold) that is bonded to the heater body.


Mechanical Thermostats( Creep Action | Snap Action )

There are two basic types of mechanical thermostats: Creep Action and Snap Action.There are two basic types of mechanical thermostats: Creep Action and Snap Action.

Both are based on a bimetal expansion-contraction principle and nearly all are pre-set to a specific temperature (non-adjustable). If the application requires very close temperature control an electronic controller with sensor is suggested over the mechanical thermostat.

Freeze protection, enclosure temperature and high limit protection are the applications best suited for the low cost mechanical thermostat.

Creep Action
The creep action units are constructed with a bimetal strip that curves with the temperature excursions to provide the mechanical action of make and break for the contacts. This provides a close differential between on/off, but can cause radio frequency interference in enclosures that have sensitive electronics. The temperature setting is factory preset and has the range of between 40°F and 300°F, +/- 5°F. Maximum amperage of these units is 8 amps at 120 volts. These small thermostats are commonly used as motor protectors or over temperature protectors in appliance applications.The creep action units are constructed with a bimetal strip that curves with the temperature excursions to provide the mechanical action of make and break for the contacts. This provides a close differential between on/off, but can cause radio frequency interference in enclosures that have sensitive electronics. The temperature setting is factory preset and has the range of between 40°F and 300°F, +/- 5°F. Maximum amperage of these units is 8 amps at 120 volts. These small thermostats are commonly used as motor protectors or over temperature protectors in appliance applications.

Snap Action
Heaters can be fabricated with thermostats, thermal fuses, thermocouples and resistance temperature detectors (RTD) as an integral part of the heater.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 a 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.

Thermal Fuses
aThermal fuses open the circuit if the heater exceeds the selected fuse temperature. They are a one time over temperature protection device that can prevent heater runaway in the event that a control device has frozen in the on position. Testing is suggested to select the location and temperature setting of the fuse to protect your product most effectively.

Fuses are preset with a range of 150°F to 460°F. Electrical ratings are 120/250 VAC and 15 amp maximum. They must be covered or enclosed because the outer case of the fuse is electrically live.

Thermocouples & Resistance - Temperature Devices (RTD)

These devices are most commonly very small and can be attached to the heater with a patch of silicone rubber/fiberglass. Almost any type thermocouple can be used. Type ”J” is most commonly employed.

RTDs are either 100 Ohm or 1000 Ohm two conductor type. Special sensors can be provided to your specifications and we can mount customer-supplied sensors.

Flexible Heaters Thermal Fuses
704-399-4248