How does the Temperature differential set point work?

[fixbear]

What it means is that the control will cut out at a set  temperature and cut in 8 degrees above it.  Some work backward, and cut out below and come in at set point.

 

It is used to prevent short cycles of the compressor system.  Manufacturers of commercial coolers know how  much temperature rise there is in a box when one opens the door. So they design the proper differential in there control. Short cycling uses more energy and causes premature electrical problems.  It takes 17 times full run current to start a motor.  So longer run times are desirable with refrigeration. 

 

8 degrees would be a air sensing control.  Some coil sensing coolers would have as much as 38 degrees.  A minimum setting would be 5.  And yes, that is well into freezing.  Intentionally to prolong the off cycle and make use of what is called the latent heat of solidification. So a bottle or meat cooler can have a coil down to 10 degrees. Box temp about 30 to 31. Then the off cycle has to come all the way up to 36 to 38 degrees.  The only change from that is a floral case or endive storage. They will not take it that cold without damage..