Peltier-TEC Fermentation control

[DaleyBrew]

Hi Everyone,

I'm brewing one gallon batches these days and I want to dial in fermentation control with out a separate fridge (I'm in a small apartment). I worked up this diagram of what I think might be a good Pelteir cooling system for a small amount of liquid (water and beer), however, I'm not entirely sure everything is correct. I have a couple of questions-

1- can I cool with water on one side of the TEC and air on the other?
2- I'm not entirely sure how to turn the fan, TEC and Pump on at the same time when the temp rises.

I was hoping to use a switching power source and just control the live wire from AC with an SSR but I've read that this might not be the safest way to go since a) there can be some power leakage through the SSR which would still power the SMPS b) SSR's tend to fail with the circuit closed.

If any electronics people could chime in with some suggestions that would be really helpful.


Thanks!!!!


Diagram attached

 

[alphaomega]

Peltiers can and have been used to control fermentation (just do a search on the forum), but it is a tricky business. You really need to understand how these things work. You can use an on/off scheme for controlling temperature, but that puts thermal stress on the TEC and will wear it out prematurely (that might not be an issue, you just need to know). PWM is also possible, but will lower the efficiency even more (and it is not good to start with).
Also, if you go for water cooling, then it is the heating side that needs it. TEC's can only create a temp difference of so much between the hot and cool side, so you really need extremely good cooling for the hot side.
Efficiency will be much better if not running at full voltage. And it is much better with many smaller (powerwise) TEC's than one large. Maintaining ferm temp, should not be all that hard, but lowering the temp in a reasonable amount of time will.
So, in short, it can be done and it can be 'good', but you need to do the 'homework' on these. Air to air and using many, is probably the easiest way to success.

Cheers!