HVAC Control in the New Millennium.pdf - HVAC.Amickracing

Advanced HVAC Control, Information Technology and Open Systemscomputer interface. With intelligent feedback programming, maintenancepersonnel are freed from tuning and modifying automation systemson a seasonal basis. Tasks such as maintaining mechanical components,scheduled maintenance, and learning existing building deficienciescan become maintenance priorities. In a truly intelligent programthere are no feedforward anticipated schedules, switches, or need forowner intervention to change setpoints and tune loops constantly.There will be less overall user interface errors that are commonwhen operators must scan programs. There are no points locked inmanual since the system no longer requires a user to lock things out oradjust for problem conditions.Feedforward ErrorsErrors that occur from feedforward instead of feedback programmingresult in higher maintenance costs. Feedforward error conditionsinclude changing summer/winter switches in software and tuning controlparameters too often or on a seasonal basis.Shutting off boilers and then turning them back on when theweather unexpectedly cools down is another one of these problems.Changing outdoor air, boiler and radiation schedules and resettingfreeze stats also occur too often.Modifying programming for cooling unit cycling is a similar problemalong with answering cold complaints from cooling cycling due tounstable operation and answering too-warm complaints for single-stagegas valves overshooting. Cooling units can be damaged from incorrectoperation and outdoor temperature and boiler loops can fight with coolingloops from feedforward error. Cold complaints in building interiorscan occur from shutting down boilers from feedforward programming.Checking software for bugs and the causes for incorrect operationsunder specific conditions are also common occurrences withfeedforward programming.DDC and Object TechnologyDDC moves at a rapid rate and many upgrades are based on theperformance results of other field applications. The Visual Icon DesignMethod (VIDM) is derived from flow charting and desktop publishing.©2001 by The Fairmont Press, Inc. All rights reserved.