Orange County NC Website
Browse       Search
Orange County West Campus Office Building -HVAC <br />PDC Project 23020 In-Row Computer Room Air Conditioners 23 81 24.01 - 6 <br />B.Temperature Compensation <br />1.The controller shall be able to adjust the capacity output based on supply and return <br />temperature conditions to meet SLA guidelines while operating to highest efficiency. <br />C.Humidity Control <br />1.Dew point and relative humidity control methods shall be available (based on user <br />preference)for humidity control within the conditioned space <br />3.05 MULTI-UNIT COORDINATION <br />A.Controller teamwork shall save energy by preventing multiple units in an area from operating in <br />opposing modes.Teamwork allows the control to optimize a group of connected cooling units <br />equipped with same controls using the U2U (Unit-to-Unit)network.There shall be three modes of <br />teamwork operation: <br />1.Teamwork Mode 1:Is best in small rooms with balanced heat loads.The controlling <br />temperature and humidity sensor readings of all units in operation (fan on)are collected to be <br />used for an average or worst-case sensor reading (user selectable).The master unit shall <br />send the operating requirements to all operating units in the group.The control band <br />(temperature,fan,and humidity)is divided and shared among the units in the group. <br />2.Teamwork Mode 2:The controller calculates the worse-case demand for heating,cooling <br />humidification and dehumidification.Based on the greatest demand within the group,each <br />unit operates independently,meaning that the unit may respond to the thermal load and <br />humidity conditions based on the unit's controlling sensors. <br />3.Teamwork Mode 3 -Optimized Aisle:May be employed in large and small rooms with varying <br />heat loads.Optimized Aisle is the most efficient teamwork mode that allows the unit to match <br />cooling capacity with heat load.In the Optimized Aisle mode,the fans operate in parallel. <br />Fans can be controlled exclusively by remote temperature or using static pressure with a <br />secondary remote temperature sensor(s)as an override to ensure that the inlet rack <br />temperature is being met.Cooling (Compressors)is controlled through unit supply-air <br />conditions.Controller calculates the average or worst-case sensor reading (user-selectable) <br />for heating,cooling humidification,and dehumidification.Based on the demand within the <br />group,units will be allowed to operate within that mode until room conditions are satisfied. <br />3.06 STANDBY LEAD-LAG <br />A.The controller shall allow scheduled rotation to keep equal run time on units and provide <br />automated emergency rotation of operating and standby units. <br />3.07 STANDBY UNIT CASCADING <br />A.The controller cascade option shall allow the units to turn On and Off based on heat load when <br />utilizing Optimized Aisle,Teamwork Mode 3 and remote temperature sensors.Cascade mode <br />dynamically coordinates the fan speed to save energy and to meet the cooling demands.For <br />instance,with a control group of six units and only 50%of the heat load,the controller shall <br />operate only four units at 80%fan speed and leave the other two units in standby.As the heat load <br />increases,the controller shall automatically respond to the additional load and bring on another <br />unit,increasing the units in operation to five.As the heat load shifts up or down,the control shall <br />meet the needs by cascading units On or putting them into standby. <br />3.08 WIRED SUPPLY SENSOR <br />A.Each controller shall have one factory-supplied and connected supply-air sensor that may be used <br />as a controlling sensor or reference.When multiple sensors are applied for control purposes,the <br />user shall be able to control based on a maximum or average temperature reading. <br />3.09 VIRTUAL MASTER <br />A.As part of the robust architecture of the control,it shall allow for a virtual master that coordinates <br />operation.The Virtual Master function shall provide smooth control operation if the group's <br />communication is compromised.When the lead unit,which is in charge of component staging in <br />teamwork,unit staging and standby rotation,becomes disconnected from the network,the system <br />shall automatically assign a virtual master.The virtual master shall assume the same <br />responsibilities as the master until communication is restored. <br />Docusign Envelope ID: 8DED1454-68D2-4E36-9FC6-E56FF2124E5D