Honeywell EXCEL 5000 User Manual page 239

EXCEL CARE CONTROL ICONS ALPHABETIC REFERENCE
Operation The following diagram illustrates ZEB operation
ZEB Mixed Air Operation
When the ZEB/Load reset mode in the internal parameters dialog box is equal to 1
(ZEB), the application includes mixed air damper setpoint management as follows.
If all three zone temperatures (X1, X2, X3) are within the zero energy range, ZEB
controls temperature only through the mixed air dampers. Average zone
temperature (X3) is the determining factor for the calculation of mixed air setpoint.
ZEB generates a setpoint at Y5 if the following applies:
Y5=P7, if X3 > X5 + P3
This relationship means that the mixed air setpoint is limited to the minimum mixed
air setpoint when the average zone temperature (X3) is at the upper end of the zero
energy range.
Y5 = P7 + P13, if X3 < X5 - P3
This relationship means that the mixed air setpoint is limited to the sum of minimum
mixed air setpoint and mixed air reset range when X3 is at the lower end of the zero
energy range. And, when the average zone temperature is within the ZEB:
Example:
Maximum zone temperature X1 = 70
Minimum zone temperature X2 = 66
Average zone temperature X3 = 66
Comfort range P3 = 4FDeg
Min. mixed air setpoint P7 = 55
Mixed air reset range P13 = 12FDeg
Room temperature setpoint (for example, from a Time Program) X5 = 68
ZEB Cooling Operation
241 74-5577–33 (US)
EN2B-0184 GE51 R0518 (Europe)