I am still looking for some form of affordable electronic expansion for my overclocking related systems. This will use R410A and later R170 in the CPU evaporator stage.

A stepper motor controlled EEV would be the first on my list, but it's cost is prohibitive.

Now another weird idea: I have an externally equalised R134a TEV which I don't use anymore. I also have a few TEC's which I don't use anymore. So, to convert a TEV into a heat motor, I could put the bulb on one side of the TEC, and another space filled with R134a which is connected to the external equaliser input on the other side of the TEC.

Now, by varying the current and polarity of the TEC supply, I could control the TEV.

The only problem is the sealing of the external equaliser chamber from the main refrigerant space. The R134a will probably leak away into the main refrigerant system, or R410A/R170 will leak into the external equaliser chamber, making this idea useless.

Has anyone else a good idea on how to electronically control a TEV?