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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Dear list,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I am modelling an HVAC plant at a component level. The air handling unit includes a 4-stage heater, which can operate in one of these 4 stages: 20kW 40kW 60kW and 80kW. I have managed to control the heater with a PID controller however I have not found a way to force it to take only these 4 discrete values. Are there any techniques integrated in Esp-r in order to model/control such a component?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black;mso-fareast-language:EN-GB'>Kind regards,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black;mso-fareast-language:EN-GB'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black;mso-fareast-language:EN-GB'>-<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black;mso-fareast-language:EN-GB'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black;mso-fareast-language:EN-GB'>Dimitrios Sfakianakis</span><span style='font-size:8.0pt;color:#548DD4;mso-fareast-language:EN-GB'><o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>