-Master controller (top) drives the chest freezer (15 cu ft) down to lowest needed temp.
-Slave controllers (bottom two) heat the their respective fermentors with the DIY FermWrap from Reptile Basics . com
Concept has been proven... I lagered a batch of beer while fermenting an Ale (38*F and 62*F respectively)
See this thread
for details on my ferm chamber.
It's also linked in my signature line.