I am having trouble using the units to manipulate convection coefficient units that include temperature deltas, such as BTU/(hr*ft^2*F), I can't get past the default to degrees Kelvin. Has anyone run into this before? I know Mathcad has unit of delta C and delta F for use in these callouts.

You have to define the delta T yourself. I put mine at the top in the gray area. Define them as DC=K (kelvin) and DF=(5/9)K.
Also, when I work with values, many of the thermal coefficients show the value in terms of degrees F or degrees C I automatically substitute this value for DF or DC
Note: D=Delta
This was discussed here http://en.smath.info/forum/yaf_postst1526_Temperature-units-handling.aspx