A thermal actuator is a component in the main operation of a device that produces linear movement. The expansion and contraction of heat sensitive materials within the device causes the thermal actuator to move linearly. It is to unify temperature sensing and actuation into one device. You can find the thermal actuator working principles in thermostat products, thermal bypass valve products, thermostatic balancing valves, and many more.
Many devices that control temperature, mix fluids, limit overheating, or protect against freezing commonly use thermal actuators The thermal actuator has a main element that can expand and contract according to temperature and then make the piston move. The key element is a temperature-sensitive material—most commonly a phase-change wax—that expands significantly when heated.
The primary sensing element is a refined paraffin wax. While other materials like gas or liquid can expand with heat, specialized wax is the industry standard for HVAC and industrial valves due to its high expansion force and predictable melting point. Many use wax as a key element where the the wax is carefully engineered so that phase changes can occur within a certain temperature range. Just like when the material passes the melting point.
As the wax reaches its melting point, it undergoes a phase change, significantly increasing its volume. Then the piston will move. After a while, the temperature drops again even below the melting point. This makes the wax turn back into a solid from a liquid. As the wax cools and contracts, the internal pressure on the diaphragm is released. A heavy-duty return spring then forces the piston back to its original position, ensuring the valve closes (or opens) reliably every time.
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Basic Thermal Actuator Working Principles
Thermal actuators are important devices in HVAC industry that utilize the principle of thermal expansion to convert temperature changes into mechanical motion. This process begins with the selection of materials that have a high coefficient of thermal expansion. When exposed to a heat source, which could be electrical, chemical, or environmental, these materials expand. This expansion is cleverly designed to translate into mechanical movement, such as a piston moving or a rotary motion, depending on the design of the actuator.
The control and precision of these actuators are remarkable. By regulating the temperature, the extent of the material’s expansion and thus the movement of the actuator can be precisely controlled. This is often managed through sophisticated control systems that monitor and adjust the heat input as needed. Once the heat source is reduced or removed, the material contracts back to its original size, allowing the actuator to return to its initial state. Thermal actuators find their applications in various fields, notably in HVAC controls, valve operations in piping systems, and in machinery where precise motion control in response to temperature changes is essential. Their reliability and ability to operate without external power in some cases make them an invaluable tool in industrial and commercial settings.
Watch: A Visual Guide To Thermal Actuator Operation
To see how theory translates into reliable performance, watch our operational guide below. This video demonstrates the practical integration of the LEGOM thermal actuator within a complete HVAC system—from unboxing to the digital synchronization between the wiring center and the manifold. You will see the actuator’s smooth response to temperature settings and how the visual position indicator allows for easy monitoring during both manual and automatic modes.
The Advantages of Using a Thermal Actuator
Any equipment that requires temperature regulation and a valve control system always needs a thermal actuator working principles. Thermal actuators have a number of advantages for fast temperature setting, energy saving and adequate control systems.
You can imagine if we still use traditional principles for temperature setting. How much electrical power will the equipment require? Then, how long do we have to wait until the equipment works to heat the room or water?
Thermal actuators are a solution for building owners and for the environment, as they reduce the need for complex electrical components such as motors, solenoids, and battery-powered systems. Compared with conventional electrically driven valves, overall electricity consumption is significantly lower, helping to reduce dependence on energy sources that still rely heavily on fossil fuels.
In many applications, thermal valves require only a small amount of electrical power to operate. This low power input is used solely to generate heat rather than to drive a motor, allowing the actuator to function reliably with minimal energy consumption. As a result, system complexity is reduced and the risk of electrical failure or short circuit is significantly lower.
Installation of Thermal Actuator
The components in the thermal actuator are quite simple. This makes installation of thermal actuators faster. Apart from that, the total cost of manufacturing and installation is lower than traditional systems. The component size of this actuator is also compact so it can save installation space.
Reliable in Extreme Conditions
A fast and efficient thermal actuator system is always safer and superior to traditional setups. There will be no electrical short circuit in every working step and the output force is also high without any worry.
Very Economical
The long service life of each thermal actuator product makes people hunt for it. This guarantee comes entirely from the company that produces it from quality materials. During the period of use there is no sound at all so it doesn’t cause noise and air pollution around you. Meanwhile, what is most surprising is that thermal actuators generally require minimal maintenance and do not need frequent calibration.
Thermal Actuator Applications
The material that is often an important part of the thermal actuator is wax. The use of wax is suitable for any reason. Wax has the property of not being compressed easily so it is easy to produce large forces. If there is no thermal actuator with wax then there will be no underfloor heating that can last a long time and save energy.
World aerospace products also need thermal actuator working principle to make smooth movements in any process. Thermostatic actuators do not require electrical energy. This actuator can release its own energy so it has potential for applications in explosion proof environments. All movements are only temperature based so that the actuator can integrate with various objects, systems, and manifolds.
All systems that require a more powerful source during power outages should have this thermal actuator technology. A number of special designs for hydraulic oil cooling for ground military equipment and electronic cooling for high performance aircraft also employ the thermal actuator working principles in a specialized manner. Army tanks also have thermostatic control or their heat exchangers. Likewise, naval radar systems require as fast temperature control as possible.
Thermal Actuator Manufacturer
The applications of the thermal actuator working principles are so wide. Starting from your own home, factories, up to the country’s military defense. As a specialized HVAC manufacturer and global supplier, Legom is dedicated to advancing energy-efficient thermal technology. Our latest generation of wax thermal actuators is engineered for precision, longevity, and sustainability.
By eliminating the need for constant electrical consumption and reducing reliance on complex electronic waste, our products help building owners and industrial partners reduce their carbon footprint.
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Global Reach: Serving partners in over 90 countries.
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Proven Quality: 400+ industrial partners rely on our technology for mission-critical systems.
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Custom Engineering: We offer specialized designs for HVAC, automotive, and aerospace applications.
Visit our manufacturing facility in China or contact our technical team online to discuss your specific actuation requirements.
Quality Meets Reliability
At LEGOM, our engineering focuses on certified performance and environmental responsibility.
| Feature | LEGOM Thermal Actuator Benefit |
| Certifications | CE and RoHS Certified for global safety and environmental compliance. |
| Acoustics | Noiseless Operation: Ideal for high-end residential and hospitality environments. |
| Efficiency | Low Power Consumption: Optimized for energy-saving green building projects. |
| Maintenance | Zero-Maintenance Design: No gears or motors to service or calibrate. |
| Deployment | Easy Installation |
Thermal Actuator Assembling Process Video
Lastly, you can view our original video below to see the thermal actuator assembly process in the factory.