Heat sources and data logging

Click on images for an awesome view...

The other day I scored a stirring hotplate from the thrift store for $6.  It looked new and is originally about $500-$600.  The value in this heat source is the stability of temperature over time.  I used a datalogger and collected about 7,192 data points to illustrate it.  

• On the left: the blue box, the profile represents the heating of 2 gallons of water on heat setting 3, 
• Next is the black box showing the cooling period when I turned the heat down to "2"
• The green box shows the same 2 gallons heated at the lower setting and finally, 
• The black box on the right shows water heated in a slow cooker, observe the oscillating pattern. 

While the slowcooker is ok for chili, it would suck for a sous vide bath (or something).

Below is a scale expansion of the blue box to show the range of temperature:

Cool or what??