Introduction to two structures of bolt heating rods
One is to directly use a bimetallic strip for temperature control. Simply put, a bimetallic strip is placed inside the bolt heating rod. Since the two sides of the bimetallic strip are made of different materials with different thermal expansion coefficients, this feature can be used to automatically disconnect when the set temperature is reached. The advantages are simple structure, low cost, and relatively high working reliability. Generally, the difference between products from regular manufacturers and counterfeit goods lies largely in this aspect. Counterfeit products use inferior materials, which are prone to fatigue after a period of use, causing them not to trip at the set temperature, leading to irreversible consequences. The disadvantage is that regardless of the material of the bimetallic strip, it has an aging period. Therefore, I suggest replacing it every two years as mentioned above.
The second is to use a thermistor to detect temperature and a thyristor to control the on/off of the heating rod.
1) The thermistor and heating rod are integrated. The advantage of this type is that installation is convenient, with fewer wires and a neat appearance. The disadvantage is that because the thermistor and heating rod are close together, the internal temperature of the heating rod often reaches the set temperature while the water temperature in the fish tank has not yet reached the set temperature. From daily use, you can see that the heating rod stops heating after a short while and then starts heating again after some time.
2) The thermistor and bolt heating rod are not integrated. The advantage of this type is faster heating. The thermistor and heating rod can be placed far apart, which overcomes the disadvantage mentioned in 1) above.
