Model-based design constructs physical systems in two stages. First, a ea~al friction network (CRN) of quantities that entails the desired behavior is constructed from a domain model. Second, a physical system is designed by assembling components such that all the causal relations specified by the CRN are imposed. The Compositional Model-based Design method, CMD, simplifies the design of complex physical systems by decomposing the specified behavior into logical portions, obtaining design fragments by constructing CRNs for each portion, and incrementally composing the CRNs and the design fragments until a designfragment is obtained whose CRN produces the entire desired behavior. Importantly, the method detects potential interactions between individual CRNs that may nullify the portions of behavior already designed for by detecting violations of the influence closure assumptions under which each CRN was formed. While this paper illustrates the method in the context of a boiler control system, the approach applies to regulatory physical systems with multiple operating ranges.