Honeywell AQ251 Manual Do Utilizador

69-1979—04

6

The AQ251’s system and thermostat (zone settings) 

parameters are stored in non-volatile memory and are 

updated as they change. 

When a power disruption or loss of power occurs, the system 

configuration is retained in memory. 

When power is restored, the AQ251 Control Panel enters 

auto-detection mode, reads its previously-stored settings, and 

initializes all AQUATROL network components according to 

their saved parameters.

POWER DISRUPTION GREATER THAN 4 HOURS
If a power disruption lasts for more than 4 hours, the AQ251 

will have discharged its internal super capacitor, and the 

DATE 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 SET 

DAY/TIME displays. This displayed message continues until 

the DATE and TIME OF DAY are updated.

NOTE: If the power failure parameter is set to Backlight 

(USER MENU > PREFERENCES/TIME), the LCD 

backlight 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 alerts and error messages display on the 

System Status Page. These messages are shown in Table 2. 

A/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 more 

than 1 minute

or

• 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 the 

boiler'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 Installer 

Setup.

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 the 

AQUATROL 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 DHW 

tank.

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 in 

progress.

DHW DISABLE

n/a

DHW call is not served because it is disabled.

LOST ZONE A-1

         …
LOST ZONE D-16

n/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.