Cartridge heaters are utilized around the flow channel to ensure uniform temperature. It is important to keep the distance between the heaters and the manifold equal or greater than 1x the diameter of the heating.

Thermocouple placement should be located equally distanced between the heating element and the flow channel and should be at least 1.5" deep to ensure an accurate reading.
If an internal thermocouple is utilized, it is important to ensure that it is located towards the center of the heating element (at least 2" away from the lead end) depending on whether the controller is grounded or ungrounded.

  Some of the most common causes of failure include:
Lead short out. This can be corrected by changing the lead type. If fiberglass leads were utilized, this could be the cause. Hot runners by nature create gases, which over time saturate the fiberglass material, allowing it to short between the leads. Depending on the ambient temperature around the lead area, Teflon leads can be utilized to correct this, as it is more resistant to gases. However, the temperature surrounding the leads cannot exceed 250'C.

  Internal thermocouple not reading correctly. This can be caused by two different reasons. One reason is the thermocouple must be located in the center of the heating element. If not, you will never obtain a correct temperature of the flow channel. The other reason is whether or not the unit is grounded or ungrounded. Consult your controller manufacturer to determine this.

 A performance issue. In a standard heater the resistance wire is evenly wound. To enhance performance, a distributed wattage heater is recommended. This is where the resistance wire is stacked at each end to compensate for the loss of heat due to various reasons. This allows for a more even heat curve.               

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