In electric water boilers or solar water tanks, it is occasionally observed on site that the heating tube shell turns black and the thermostat operates frequently. After disassembly and inspection, it is often found that the built-in protective device fails to disconnect reliably. The ZDR-720 tubular electric heater addresses such working conditions by integrating a two-in-one overheat protector inside the tube body. When overheating or water shortage dry-burning occurs, the protector quickly cuts off the power supply and remains in the disconnected state before the contacts of the power supply relay open, avoiding frequent on-off cycles.
The heating tube can be made into straight, U-shaped or W-shaped types, and the shell material is selected from stainless steel or carbon steel according to the medium. The built-in two-in-one overheat protector is connected in series in the heating circuit. After actuation, it can only be reset after the relay stops supplying power, so that repeated power-on dry-burning will not occur under abnormal conditions. This design does not rely on the control logic of external water temperature and water level instruments. The electric heating tube itself does not have a water temperature regulation function and is specially used for supporting scenarios requiring overheat and dry-burning protection.
The product is suitable for supporting heating in electric water boilers, electric hot water boilers, electric heating boilers, electric steam boilers, electric ovens, chemical equipment, plastic molding and auxiliary equipment, hot press molding machinery, cigarette machinery, rapid sealing machines, pharmaceutical machinery, sauna equipment, kitchen equipment, industrial cleaning equipment, commercial air conditioning and drinking water equipment, solar energy equipment, electric fryer equipment, wave soldering electronic automation equipment, semiconductor eutectic welding, die-casting input runner heating and other heating machinery. During installation, ensure that the heating zone is immersed in the medium, the wiring terminals remain dry, and the cause of overheating or dry-burning must be investigated before resetting the protector.
Regularly check the scaling on the surface of the heating tube, as severe scaling will affect heat transfer and trigger protection. When replacing the heating tube, confirm that the protector model matches the relay control mode to avoid protection failure due to mismatched reset logic.
