The paper considers a model for floor heating in buildings, with an electrically heated, stratified water tank, a circulation loop, a detailed description of heat transport through the floor, and a simplistic room model. The model structure is suitable for control of room temperature, and the paper discusses the use of modern simulation tools for control-relevant analysis of such models. The stratification description contains a non-differentiable buoyancy term, and two approximations are studied which circumvent this problem. The results indicate that a boundary layer approach is superior to a log-sum-exp approximation. Important basic control-relevant analysis ideas include step response (time constants), sensitivity analysis (parameter identifiability), the system zeros location (attainable performance), and Bode plots (control synthesis). The paper illustrates how such an analysis can be carried out using tools such as OpenModelica in combination with scripting language Julia.
Keywords: Thermal building model, heated water tank, floor heating, model analysis, sensitivity analysis, linearization, control architecture