ALPHABETIC REFERENCE EXCEL CARE CONTROL ICONS74-5577–33 (US) 58EN2B-0184 GE51 R0518 (Europe)Economizer / ECOFunction Legacy RACL function: Decide on the most economical system operation for full andpartial air conditioning systems.For a full air conditioning plant, it calculates the control signal (Y output) for energyrecovery on the basis of actual outdoor air enthalpy, return air enthalpy, anddemand.In partial air conditioning systems, you can use this control icon for heat recoverywith temperature comparison.ECO makes decisions based on the following information:• Is the system a full or partial air conditioning system? A full system hastemperature and humidity control. A partial system has temperature control only.• Is there mixed air damper operation or heat and humidity recovery using athermal wheel?• Which has the higher energy cost: heating or cooling?I/O Dialog BoxExcel Web / Excel Web IIInputs Four analog inputs (X1 through X4), where:X1 (Excel Web / Excel Web II: TCtl) = Temperature controller(-58F through 122F [-50C through +50C]), for example, the output of a PIDthat controls basic temperature.X2 (Excel Web / Excel Web II: HCtl) = Humidity controller(-50 through +50 percent rh), for example, the output of a PID that controlshumidity. This input is optional.X3 (Excel Web / Excel Web II: EntO) = Outdoor air enthalpy/temperatureX4 (Excel Web / Excel Web II: EntR) = Return air enthalpy/temperatureX1 and X2 expects these inputs from direct-acting controllers, that is, controllers thatreact to a deviation with a change of the positioning signal in the same direction.X3 and X4 must be the same type of input, either both temperature or both enthalpy.You can use an H, X control icon to calculate outdoor air and return air enthalpy.Output One analog output, Y (Excel Web / Excel Web II: ECO) 0 through 100 percent.
