Question
Why is my load heating when it should be cooling?
Answer
The simplest answer to this problem is also the least likely: you might have the leads on the thermoelectric cooler (TEC) backwards. If you reverse the leads of the TEC to the controller does it then work correctly? If the answer is Yes, then the problem is solved. If the answer is No, then the problem is more complicated.
A number of things need to be considered at this point:
- Is the TEC large enough for the active load? If the TEC is too small to pump away the waste heat from the load, the load temperature will rise no matter how much current the temperature controller drives to the TEC.
- There may be a thermal runaway situation. Thermal runaway can happen if the heat sink is too small to dissipate the heat pumped away from the load by the TEC. A larger heat sink is needed, or increased airflow over the existing heat sink.
- Thermal runaway can also happen if the ambient temperature is too high. Additional air flow over the heat sink may be required.
- The current limit of the controller might be set too high for the TEC. Driving too much current through the TEC may permanently damage it, so setting the current limit correctly is essential.
Reference our technical note TN-TC01: Optimizing Thermoelectric Control Systems for information on TEC control systems.