Question: When using temperature units, how do I know when to use a temperature expression and when to use a temperature object. Am seeing inconsistent behavior when using these.

I am using temperature units with thermophysical data and scientific constants but am getting inconsistent behavior when using these.  In some cases (e.g., when calling thermophysical data), it seems that it's best to use a Temperature object.  However I have tried to use scientific constants in calculations and it seems that temperature expressions work best (i.e., when using degrees K rather than deg F or deg C).  Simplifying/combining units don't seem to work when using a Temperature object (or when using expressions with deg F).  It may be something simple I am overlooking but I can't figure out the pattern of behavior yet.  I've attached a file that demonstrates the issue:  Temperature_Object_Use.mw

Thanks for any insight here.