Restrictions anywhere in the furnace’s water flow path for the furnace coil can and will cause over-temperature conditions. Restrictions can be caused by debris or calcium buildup in water lines, heat exchanger and water-cooled power cables, internal damage to water-cooled power cables such as “bird nesting”, kinking or flattening of the hose. Water-cooled power cables do fail over time and replacement is required. Life span varies depending on the amount of use, water quality, layout, and configuration. Keep in mind that a restriction is a restriction! It does not matter if it is the feed line, drain line, or coil, all will result in Furnace Drain over-temperature alarm or faults.
The use of an induction melting furnace that was not designed for the application or designed for kW output of the induction power supply, modifying water paths can also cause overtemperature issues.
Furnace lining dimensions and proper installation using quality material is also very important, making changes from original design parameters is not recommended and strongly discouraged. Not having a proper amount of refractory “back-up” material will cause overheating and damage to the furnace coil.