TEC Zoning Control System for Stand-Alone and BACnet® MS/TP ...

- It is possible for an internal zone to be slightly overcooled during peaksummer cooling loads. This situation happens when the rooftop controllersupplies its maximum cooling capacity, and when the volume of cold airdetermined by the minimum position of the zone damper during occupiedperiods is already providing too much cooling capacity to the internal zone.- It is also possible for an internal zone to be slightly overheated during peakwinter heating loads. This situation happens when the rooftop controllersupplies its maximum heating capacity; and when the volume of hot airdetermined by the minimum position of the zone damper during occupiedperiods is already providing too much heat, for which the internal zonesrarely need.• External zones considered to be of primary importance should have both theirheating and cooling weight set to 100%.• Zones considered to be of secondary importance may have their weight set to alesser value than 100%, to reflect the importance they have in the total votingdemand calculations.• Some zones (for example, an office surrounded by panoramic windows) mayexperience problematic behavior while in their peak heating or cooling mode,due to location, design, and/or degree of exposure. These problematic zonescan have their peak load demand satisfied; however, this usually results inhigher energy costs since some of the other zones in the system are slightlyoverheated or overcooled. The installer is responsible for properly identifyingthese problematic areas and determining if they should be fully satisfied (at acertain energy expense) or if they should be left unsatisfied during specificpeak load periods, to reduce energy consumption and for the greater good ofthe rest of the zones in the system.- Adding many voting zones (including problematic areas) to a rooftopcontroller provides greater occupancy comfort at higher energy costs.- Restricting the number of voting zones (including problematic areas) to arooftop controller provides energy savings at the expense of occupancycomfort in some of the zones in the system.Minimum, Maximum, and Heat Flow AdjustmentsAlthough system balancing can be accomplished using configuration settingswithin the zone controller, we recommend installing a balancing damper at thebalancing side takeoff of all zones. A balancing damper reduces excessive airflowand the noise that goes with it, if the zones and/or associated ductwork areoversized.Minimum Position Adjustment (Min Pos Parameter)This parameter sets the minimum position of the zone damper to deliver theminimum amount of air to the zone in all conditions. When powered up, thedamper never closes below the minimum position setting.TEC Zoning Control System for Stand-Alone and BACnet® MS/TP Networked ApplicationsTechnical Bulletin27