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Our Thermal Actuators

Thermostatic Actuators convert temperature change into motion. The technology utilized in our thermal actuators is referred to as “phase change” technology. ThermOmegaTech® has incorporated this technology into the Thermoloid® wax-blend material that makes all our thermostatic valves operate. At the heart of each of our valves is a highly refined paraffin wax that changes phase from solid-to-liquid, on increasing temperature, and from liquid-to-solid, on decreasing temperature. The volume change is transduced into a linear, repeatable mechanical motion. Due to the non-compressible nature of the wax, this motion can produce a significant amount of force.

Created in a variety of sizes and temperatures, our self-actuating thermal actuators are utilized in many valve configurations to control flow in response to temperature changes across a wide range of applications and industries including aerospace & defense, most often for temperature control of various fluid systems.

Our Technology - Thermal Actuator Diagram

The basic elements of a thermostatic actuator include:

  • Wax – motion producing element.
  • Cup – contains the wax.
  • Diaphragm – seals in the wax and creates motion during expansion.
  • Guide – retains the Diaphragm creating a seal while guiding the Plug and Piston.
  • Plug – transmits and amplifies the wax expansion via the Diaphragm increasing stroke.
  • Anti-Chafing Disc – prevents the Plug from extruding around Piston when force is applied.
  • Piston – transmits the Plug’s movement into useable stroke.

How it Works

The Thermoloid® material is sealed inside our actuators by a diaphragm. As the temperature increases above the melting point of the Thermoloid® material, it expands in volume and pushes against the diaphragm which in turn pushes on a piston. The piston, now in its “hot position”, acts as a valve stem opening or closing a valve.

As the Thermoloid® material begins to cool below its melting point, it compresses, and a spring returns the piston and diaphragm to their “cold position”. The phase change, and resulting large volume change, produce motion over a narrow and highly predictable temperature range. The temperature range at which the phase change occurs can be varied between -150°F to 300°F (-101°C to 149°C) depending on the chemical composition of the Thermoloid® material that is used.

Depending on your application needs we offer direct and reverse acting valves. Direct acting valves are designed to be open when the actuator is in the “cold position” while reverse acting valves are open in the “hot position”.

Direct Acting Valves are designed to be open when the actuator is in the “cold position” while Reverse Acting Valves are open in the “hot position”.

Typical Actuator Curve


  • Self-Actuating: no external power required
  • Maintenance-free: no periodic calibration
  • Highly repeatable position vs. temperature
  • Few moving parts
  • Long service life
  • Very high power to size and weight ratio, making for smaller, lighter-weight packages
  • Excellent for applications in hazardous and extreme environments

Because of the gradual transition of the phase change of the Thermoloid® material, these valves act more like modulating valves, as opposed to quick opening/closing valves. The precise motion of these thermal actuators can be used to operate a wide variety of devices, limited only by the imagination of the designer.

No external power or signal is required, making our product ideal for many hazardous and extreme environments.

Circuit Solver Actutor

Advantages of Thermostatic Valves vs Electronic Sensing / Solenoid Valves

The unique characteristics of a thermostatic valve are that temperature sensing, fluid control (open or closed loop) and valve position modulation are all inherently contained in the valve without the need for an external temperature transducer or external power. This has tremendous advantages in many applications where the traditional solution requires a temperature sensor, amplifier, control electronics, solenoid valve and DC Power.

Self-actuating thermostatic valves provide a substantial financial advantage over solenoid valves because no additional components are needed for the valve to operate which significantly reduces installation and operation costs. Since no power connection is needed, power failure will not affect valve reliability or cause hazardous conditions.

Thermal actuated valves are highly reliable, repeatable, compact, low cost devices used for many fluid temperature control applications. They are the best temperature solution to a temperature problem.

Thermostatic Valve Thermal Actuators

Thermal Actuators Advantages of Thermostatic Valve vs Electronic Sensing / Solenoid Valve