You may have noticed that many floor heating valves or radiator side panels have a white knob with markings (1 to 5 levels). It doesn't require power plug or battery installation, yet it can function like a smart air conditioner, adjusting the water flow size based on the room temperature. When the room temperature is high, it reduces the water flow; when it's low, it increases it. This "electric-free intelligent temperature regulator" is essentially a thermostatic valve. It achieves this by ingeniously leveraging the most basic physical phenomenon - thermal expansion and contraction.
1. Disassemble the temperature control valve
What are the two parts it consists of? The constant temperature control valve is mainly composed of two parts that are fastened together: the temperature control head (the plastic casing that can rotate on the outside): This is its "brain" and "sensor", responsible for sensing the room temperature and generating the driving force. The valve body and the valve core (the metal part connected to the water pipe): This is its "actuator", responsible for mechanically opening or closing the water flow.
2. The secret of the core without electricity
The "thermistor" in the temperature control head The internal part of the temperature control head contains a very crucial component called a thermistor. The thermistor is a sealed metal or polymer plastic capsule filled with substances that are extremely sensitive to temperature - usually specially formulated liquids, high-purity paraffin wax, or volatile gases. Its working process is as follows: When the room temperature rises: The hot air in the room flows through the temperature control head, causing the temperature-sensitive medium inside the thermistor to expand rapidly.
The expanded medium pushes the top rod at the bottom of the temperature sensor outward. The top rod vertically presses the temperature control valve core on the valve body, narrowing the water flow channel. The flow of hot water decreases, the heat dissipation of the radiator or underfloor heating system slows down, and the room temperature stops rising. When the room temperature drops, the room becomes colder. The temperature-sensitive medium inside the temperature sensor contracts and condenses, reducing its volume and weakening the pushing force. A spring inside the valve core pushes the top rod back, reopening the valve and widening the water flow channel. More hot water flows in, and the room temperature rises accordingly.
The heating element is like a "water ball that automatically expands or shrinks according to the temperature". When the water ball expands, it blocks the pipe opening; when it shrinks, the pipe opening automatically opens.
3. How do the external scales work?
By turning the outer knob, you are actually changing the initial distance (mechanical preload force) between the temperature control head and the valve core. When you turn to the high setting (such as 5th position, approximately 28°C): It is equivalent to moving the temperature control head outward, leaving more expansion space for the heating element. The heating element needs to expand very much (i.e., the room temperature rises significantly) to press against the valve core, so the room will remain at a higher temperature. When you turn to the low setting (such as 2nd position, approximately 16°C): It is equivalent to pushing the temperature control head forward, very close to the valve core. When the room temperature slightly rises, the weak expansion of the heating element can press against the valve core to close the water flow, and the room will remain at a lower temperature. Anti-freezing setting (usually a snowflake symbol "*", approximately 6°C): As long as the room temperature is above 6°C, the valve remains closed; once the room temperature drops close to the freezing point, the heating element contracts violently to open the valve, preventing water in the pipes from freezing and bursting.
আপনার বার্তাটি 20-3,000 টির মধ্যে হতে হবে!
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