Honeywell AQ251 User Operation And Maintenance

Also see for AQ251: Technical reference booklet

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Honeywell AQ251 User Operation And Maintenance Manual pdf 6 page image

AQUATROL ZONE SYNCHRONIZING BOILER RESET CONTROLS69-1979—04 6TROUBLESHOOTINGPower DisruptionThe AQ251’s system and thermostat (zone settings)parameters are stored in non-volatile memory and areupdated as they change.When a power disruption or loss of power occurs, the systemconfiguration is retained in memory.When power is restored, the AQ251 Control Panel entersauto-detection mode, reads its previously-stored settings, andinitializes all AQUATROL network components according totheir saved parameters.POWER DISRUPTION GREATER THAN 4 HOURSIf a power disruption lasts for more than 4 hours, the AQ251will have discharged its internal super capacitor, and theDATE and TIME OF DAY settings will need to be reset.Upon restart, the AQ251 displays its clock settings as: YEAR= 2008, MONTH = JAN, DATE = 1. The message PLS SETDAY/TIME displays. This displayed message continues untilthe DATE and TIME OF DAY are updated.NOTE: If the power failure parameter is set to Backlight(USER MENU > PREFERENCES/TIME), the LCDbacklight flashes repeatedly, along with the mes-sage.The AQ251 remains permanently in OCCUPIED (or Comfort)mode until the DAY and TIME OF DAY are updated.System Status and Error CodesSystem status alerts and error messages display on theSystem Status Page. These messages are shown in Table 2.Table 2. LCD Status Notices and Error Messages.LCD Display Parameter MeaningA/C MIN. OFF TIME n/a The A/C compressor is disabled, because the minimum OFF time has not yet elapsed.A/C MIN. ON TIME n/a The A/C compressor is active and the minimum ON time has not yet elapsed.AUX IN EM. SHUT n/a Auxiliary Input's Emergency Shut Down is active.BOILER: EM SHUT Boiler is disabled, because the AQ251 is in Emergency Shut Down mode.FRZ PROT Boiler freeze protection activated:• Communication between Control Module and Zoning Module has been lost for morethan 1 minuteor• Boiler supply temperature is less than 50°F (10°C)HEAT DHW Boiler is active to serve DHW.HEATING Boiler is active to serve zones.IDLE Boiler is not active.INIT Boiler contacts (terminals 22 and 23) on the AQ1520, which are connected to theboiler's T-T terminals, have been shorted and the boiler is beginning its firing sequence.INST PURG Boiler is active while the AQ251 is conducting the PURGE operation in the InstallerSetup.NSTALL Boiler is in ready mode during Installer Setup.PMP EXER Boiler is disabled while the AQ251 is exercising all pumps and valves connected to theAQUATROL network.POST PURG Boiler is active with Post Purge operation and is sending the purged water to the Boiler(Primary) loop.PURGE DHW Boiler is active with Post Purge operation and is sending the purged water to the DHWtank.CALL FOR COOL n/a At least one zone with a programmable thermostat requires cooling.CALL FOR DHW n/a The DHW requires heat.CALL FOR HEAT n/a At least one zone requires heat.CWSD ACTIVE n/a Zone calls for cooling are not served because CWSD (Cold Weather Shutdown) is inprogress.DHW DISABLE n/a DHW call is not served because it is disabled.LOST ZONE A-1…LOST ZONE D-16n/a Lost communication with a zone (A-1 to A-16, B-1 to B-16, C-1 to C-16, or D-1 to D-16).NO DHW PROBE n/a No DHW sensor connected or it is defective.NO OUTDOOR PROBE n/a No outdoor sensor connected or it is defective.

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