Creo Simulate > Creating Analyses > Thermal Analysis > Boundary Condition and Load Sets in Thermal Analyses
  
Boundary Condition and Load Sets in Thermal Analyses
When defining thermal analyses, keep the following guidelines in mind:
For both steady and transient thermal analyses, you do not have to select a load set.
For a transient thermal analysis, you do not have to select a boundary condition set. However, you must select one or more load sets for the analysis to be valid.
For steady thermal analyses, you must select one boundary condition set.
For both steady and transient thermal analyses, you can combine more than one constraint set into a new single set during the analysis.
For steady thermal analyses, you can merge the loads of all selected load sets.
If you delete a boundary condition set or load set in the model after you include it in an analysis, that set is removed from the analysis.
Even if you create a new set with the same name as the set you deleted, you must edit the analysis and select the set name again. Otherwise, you can invalidate the analysis and any design studies in which you included the analysis.