Sous Vide vs Induction for BIAB Step Mash?

[Gytaryst]

EDITED:
My original reason for posting this was to hopefully get opinions about using a sous vide immersion recirculator or an induction cook top for step mashing in small BIAB batches. But after researching it further I've pretty much settled on the sous vide method.

Now I'm trying to decide if I want to put the unit directly in the wort to mash, or if I want to use another pot with just water, a copper coil and a small DC magnetic pump. The sous vide units are designed to heat water so I'm not sure what kind of unforeseen problems I might run into using it to heat the wort directly.

My second question is unrelated. I would also like to start experimenting with different fermentation temp schedules as well. Since I'm only doing 1.5 gallon batches I was wondering if anyone has done, or seen, or heard about any ideas for small multi-fermentation chambers. I would like to have or build something with the capability of fermenting four 1.5 gallon batches at one time but with the ability to precisely control the temperature separately for each batch. Each chamber only has to be big enough to hold a 2 gallon fermenter. I looked into the peltier method but I live in Phoenix where ambient temp in the summer can be 110 to 120. Since thermoelectric method only cools down to roughly 30° or 40° below ambient that's not an option. I would need a compressor.

I'm looking for a way to use one compressor but to regulate the temperature separately in four small chambers.

 

[Pappers_]

Very cool, let us know how the mash temp control goes.

As for fermentation temp control, I don't know. Little dorm fridges with digital controllers? There is a product for carboys that controls temps, for individual fermenters. I can't think of the name of it. But it would be too large for one gallon batches in any case.

 

[Gytaryst]

... As for fermentation temp control, I don't know. Little dorm fridges with digital controllers? There is a product for carboys that controls temps, for individual fermenters. I can't think of the name of it. But it would be too large for one gallon batches in any case.

I thought about those. You're right they would be overkill on small batches and they're way too expensive anyway.

I'm basically trying to find a way to split a refrigerator into four separate compartments where I can regulate the temperature differently in each. Maybe something with a copper coil filled with antifreeze. (just spit-balling).

I'm sure a lot of people have probably thought about doing something like this before me.