17. How can the operator detect if a temperature control unit is defective or functioning poorly?

One factor in judging whether a temperature control unit is functioning properly is the temperature. Set-point and actual temperatures must correspond (±1 to ±2 °C). If this is not the case, the unit is not operating properly.
If cooling remains on continuously and the actual temperature nevertheless remains too high, either the unit is too small for the application, or one of the following problems may exist: the cooling water connection is closed; the cooler is coated with scale; or the filter in the cooling water network is dirty.
Possible causes of insufficient temperatures: heater, heat contactor, or solid-state relay is defective; or the solenoid valve for the cooler does not close properly, causing water to flow through the cooler continuously. If the actual temperature oscillates about the set-point value due to incorrect setting of the control parameters (alternating heating and cooling), energy is wasted and stress on the unit increased.
As the temperature is usually measured in the medium (water or oil), agreement between the set-point and actual temperatures displayed does not necessarily mean that the consumer temperature is being controlled properly. If the flow rate is insufficient, the temperature will not be transferred to the consumer fully. Therefore, the flow rate must also be checked which can be done using a built-in or external flow meter.

FAQ overview