answered 2016-12-06 11:57:07 -0600
This seems to be a bug in OpenModelica. I opened a ticket at https://trac.openmodelica.org/OpenModelica/ticket/4172#ticket
The model Buildings.Fluid.Boilers.Examples.BoilerPolynomial works with Dymola and JModelica.
Buildings.Fluid.Boilers.Examples.BoilerPolynomial