Honeywell Boiler AQ251 User Manual

AQUATROL Zone Synchronizing  
Boiler Reset Controls  
AQ251  
USER OPERATION AND MAINTENANCE  
thermostats in the home can display the actual outdoor  
temperature when an outdoor sensor is connected to the  
AQ251 Control Panel.  
WARNING  
Only trained, experienced, licensed service  
technicians should service this Control Panel. The  
front cover of the AQ251 Control Panel should not  
be removed, as this will expose the user to  
potentially dangerous line voltage (120V)  
electricity.  
Congratulations!  
The AQUATROL AQ251 installed on your heating system is  
the most powerful, yet user-friendly hydronic heating control  
system available on the market for residential and light  
commercial installations.  
APPLICATION  
The AQ251 series of AQUATROL® Boiler Reset Controls  
provides simplified, energy-efficient outdoor temperature  
compensated control of single-temperature, residential  
hydronic heating systems. The AQ251 easily converts a single  
zone heating system into a room-by-room comfort control  
system, or upgrades a basic, relay-logic zoning system to  
intelligent “Zone of Greatest Demand” control with outdoor  
reset for increased energy efficiency and with reduced boiler  
cycling.  
This instruction sheet contains all the information you need to  
program the comfort settings of the AQ251 and to customize  
its operation for your home or business. For detailed  
information on the operation of this control, please consult the  
trained hydronic heating professional that installed the AQ251  
control.  
CONTENTS  
LCD Display Panel Layout ................................................  
System Status and Error Codes .......................................  
3
6
AQ251 boiler controls can ensure ample supply of hot water  
for both space heating and priority generation of domestic hot  
water for bathing, dishes and laundry.  
When AQ1000 communicating thermostats are used with the  
AQ251 Zoning Modules, they can use the same wiring as  
existing thermostats. Night setback operation can be  
programmed from the AQ251 panel. Thanks to the network  
communication capability of the AQ251 controls, AQ1000  
This AQUATROL AQ251 Control Panel was installed by a trained hydronic heating contractor.  
To service this product, or for any questions relating to its installation, please contact:  
Installing contractor: ________________________________________________________  
Address: __________________________________________________________________  
Phone: (_______) __________________________________________________________  
69-1979-04  
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AQUATROL ZONE SYNCHRONIZING BOILER RESET CONTROLS  
NOTES:  
LCD Display Panel Layout  
1.  
When setting times for the setback schedule, you  
must use the or + button to change the time.  
The OK button, when pressed, defaults the time  
setting to “--:--” (midnight).  
The LCD on the AQ251 Control Panel is used to:  
Monitor system status and performance.  
Select and/or modify control settings for the hydronic  
system.  
2.  
Diagnose and troubleshoot system problems.  
If the active menu item leads to a further sub-menu,  
pressing the OK button displays the sub-menu options on  
the LCD. Scroll through this sub-menu to position the  
indicator arrow (←) beside the desired menu item to input  
or modify. Choose one of the options provided or input the  
desired value for the menu item. When satisfied, scroll to  
another item and your selection will be saved.  
The layout of the display is logical and simple to navigate. The  
information displays so that you can see at a glance the  
system’s operating temperatures, as well as the status of the  
system equipment, such as a call for heat, DHW pump ON,  
Boiler T-T terminals energized, etc. Fig. 1 on page 2 illustrates  
the layout and features of the LCD display panel and keypad.  
To define or modify another item within the same menu,  
scroll the up and down buttons ( or v) until the indicator  
arrow (←) is beside the desired option. Use the or +  
buttons to set the value for that item.  
^
LCD Display Navigation  
This section describes how the keypad is used to navigate the  
LCD display and menus.  
To move back (up) one level within a menu, press the  
Menu button.  
The LCD displays up to three lines of text at a time. For  
menus with more than three lines, use the up and down  
To return to the Home Page display, press the Home  
button.  
buttons ( or v) to scroll through the menu options.  
^
As the menu is scrolled up or down, the indicator arrow (←)  
shows which menu item is active.  
NOTE: The AQ251 automatically returns to the Home Page  
display after 60 minutes of inactivity on the keypad.  
If the active menu item is part of a list of predefined options  
(e.g., Day of the Week) press the or + button to scroll  
through the available options until the preferred option is  
displayed. The option is automatically saved when the  
indicator arrow is scrolled away from the value being  
edited.  
HOME PAGE DISPLAY  
The Home Page is the default view displayed on the AQ251  
Control Panel's LCD screen.  
There are two Home Page views - Simple and Detail.  
If the active menu item requires you to define a value (e.g.,  
a setpoint), use the or + button to decrease or increase  
the value until the desired value is displayed. The selection  
will be saved when the indicator arrow is scrolled up or  
down.  
Simple view shows 3 lines of text and is a brief description  
of the system operation.  
Detail view includes the same 3 lines plus 10 lines of  
additional information. Detail view is the factory default.  
The choice of the Simple or Detail Home Page view is made  
from the USER MENU > PREFERENCES/TIME menu option.  
The Home Page display information for the Simple and Detail  
views is illustrated in Fig. 2.  
KEYPAD  
LCD DISPLAY  
HOME PAGE (SIMPLE)  
WEDNESDAY  
PROGRAM:  
OUTDOOR:  
9:30A  
LEAVE  
-5  
Menu  
HOME PAGE (DETAIL)  
WEDNESDAY  
PROGRAM:  
OUTDOOR:  
TARGET:  
BOILER:  
RETURN:  
DHW:  
9:30A  
LEAVE RETRN SLEEP WAKE OCC UNOCC  
-5  
Home  
180 WWSD --  
180  
160  
100  
31  
ZONE COUNT:  
M27749  
Fig. 2. Home Page displays (Simple and Detail).  
3
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AQUATROL ZONE SYNCHRONIZING BOILER RESET CONTROLS  
The time display in 12 hour (e.g., 7:00 PM) or 24 hour  
format (e.g., 19:00).  
Programming Instructions  
Program the AQ251 by using the keypad and LCD display to  
select parameters from the User Menu. Refer to Fig. 1 on  
page 2 for an illustration of the LCD screen and keypad.  
Date and time of day – allows building owner to reset  
day and time of day in the event of a power outage of  
more than 4 hours (refer to Troubleshooting section).  
The Home Page display view, Simple or Detail. The  
factory default is Detail.  
The LCD Backlight – illuminated permanently (ON) or  
set to automatically turn off backlight after 1 hour  
(AUTO).  
provide a graphical layout of the AQ251’s User and  
Installer menus.  
When a new AQ2000 component is connected on the  
AQUATROL network, it will be seamlessly integrated in the  
system after a few seconds. If one or more components are  
disconnected or stop providing data to the network, a  
message will appear on the System Status display until the  
fault is corrected.  
POWER FAILURE  
If a power disruption lasts for more than 4 hours, the message  
PLS SET DAY/TIME displays and optionally, the AQ251's  
backlight flashes repeatedly. This displayed message  
continues until the DATE and TIME OF DAY are updated. See  
“Power Disruption Greater Than 4 Hours” on page 6.  
User Menu Overview  
ZONE SETTINGS (REQUIRES AQ1000 THERMOSTATS)  
Settings in this sub-menu define:  
The User Menu is intended for use by the building owner to  
choose the LCD display preferences, Zone Settings (including  
setpoint temperatures and setback times for each zone), and  
temperatures for the WAKE, LEAVE, RETRN (return), and  
SLEEP programs.  
The temperature setpoints (target temperatures) for  
each zone in the heating system  
The temperature setback for each zone in the heating  
system. This is the desired temperature drop when the  
heating system enters the setback program SLEEP or  
LEAVE.  
The Home Page and User Menu allow the building owner to:  
View the status of the system.  
Set up preferences for how the system information is  
displayed.  
The maximum and minimum setpoints that can be  
entered by a user at a thermostat screen for each  
zone.  
Set target temperatures for each zone (requires AQ1000  
thermostats).  
Program times of the day when the system will set back the  
temperatures for all zones (requires AQ1000 thermostats).  
Whether each zone can be set independently by the  
AQ251 (i.e., some zones can be locked while others  
are unlocked) depending on whether or not the key-  
board on a thermostat is locked. When locked, no  
changes can be made to a zone’s setpoint tempera-  
ture through the thermostat. Changes can still be  
made through the Zone Settings menu on the AQ251  
control panel.  
NOTE: If there are any problems with the system’s opera-  
tion, the AQ251 displays error codes on the System  
Status display of the LCD panel. For details on these,  
PROGRAM SETTINGS  
TO ACCESS THE USER MENU:  
Using the Program Settings sub-menu, the building owner can  
define the time of day when the entire heating system will  
change programs (e.g., from SLEEP to WAKE).  
Press the Menu button on the keypad at any time to access  
the User Menu.  
User Menu Settings  
The AQ251 has provision for four different schedule periods  
per day. They are defined as WAKE, LEAVE, RETRN (return),  
and SLEEP:  
The User menu has five sub-menus.  
“System Status”  
“Preferences/Time”  
“Zone Settings (requires AQ1000 thermostats)”  
“Program Settings”  
“Statistics” on page 5  
WAKE:  
LEAVE:  
RETRN:  
Period when you awaken and want your  
home at a comfortable temperature.  
Period when you are away from home and  
want an energy-saving temperature.  
Period when you return home and want  
your home back to a comfortable  
temperature.  
To make changes to the parameter settings in the User Menu,  
refer to “LCD Display Navigation” on page 3.  
SLEEP:  
Period when you are asleep and want an  
energy-saving temperature.  
SYSTEM STATUS  
This is a detailed list of activities going on in the heating  
system (e.g., call for heat, DHW disabled), and provide the  
building owner with a quick snapshot of the heating system’s  
operation, primarily for purposes of troubleshooting and  
system diagnostics.  
There are three modes of operation – Automatic, Occupied  
and Unoccupied:  
AUTO:  
In AUTO mode, the AQ251 follows the  
WAKE, LEAVE, RETRN, and SLEEP  
programs.  
PREFERENCES/TIME  
The preferences that the building owner can change in this  
sub-menu are:  
OCC:  
In OCC mode, the AQ251 holds the  
temperature of OCCUPIED programs  
(WAKE and RETURN). This might be used  
if the occupancy pattern of the building  
The temperature scale for the display (Fahrenheit or  
Celsius) for both the AQ251 control’s LCD and the  
zone thermostats.  
69-1979—04  
4
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AQUATROL ZONE SYNCHRONIZING BOILER RESET CONTROLS  
changes temporarily, requiring the  
temperature to be at a comfort level 24  
hours/day.  
2. Programming all days at the same time:  
Select EDIT ALL DAYS from the Program Settings  
sub-menu.  
UNOCC: In UNOCC mode, the AQ251 holds the  
temperature of UNOCCUPIED programs  
(LEAVE and SLEEP). This might be used if  
the building will be unoccupied for an  
extended period of time, such as a vacation  
period.  
A sub-menu displays where you can change the  
WAKE program time for all days, the LEAVE  
program time for all days, etc.  
When all four programs have been set, select the  
COPY TO ALL DAYS option. This displays the  
prompt: COPY TO ALL DAYS - ARE YOU SURE?.  
Select Yes by positioning the indicator arrow at YES  
and press the OK button.  
Next, the same list of days as EDIT DAILY  
(described in step 1) displays, except that all days  
now show the times for the WAKE, LEAVE, RETRN,  
and SLEEP programs that you set in the EDIT ALL  
DAYS menu.  
If you do not want all days of the week to have the  
same program schedule (e.g., weekdays different  
than weekends), you can now scroll down and  
change the program times for certain days by  
positioning the indicator arrow beside the program  
time to change and using the + or – button to  
increase or decrease the scheduled program time.  
There are two ways to set the schedule program times for  
WAKE, LEAVE, RETRN, and SLEEP:  
One day at a time  
All days at the same time  
1. One day at a time programming:  
Select EDIT DAILY from the Program Settings sub-  
menu.  
A list of four program times per day displays,  
showing the factory pre-set times for all programs:  
MON WAKE  
MON LEAVE  
MON RETRN  
MON SLEEP  
TUE WAKE  
TUE LEAVE  
TUE RETRN  
TUE SLEEP  
6:00A  
8:00A  
4:30P  
10:00P  
6:00A  
8:00A  
4:30P  
10:00P  
When the program times have been set for all days, press the  
Home button to leave the programming menus and return to  
the Home Page display. All settings take effect immediately.  
NOTES:  
SAT WAKE  
SAT LEAVE  
SAT RETRN  
SAT SLEEP  
SUN WAKE  
SUN LEAVE  
SUN RETRN  
SUN SLEEP  
6:00A  
--:--  
--:--  
10:00P  
6:00A  
--:--  
--:--  
10:00P  
1.  
2.  
Schedule times are in 15-minute intervals.  
To have the AQ251 ignore a program change  
(and therefore keep the previous program's set-  
point temperature), position the cursor beside the  
period to be ignored and press the OK button.  
The AQ251 will display “--:--” beside that program  
and, when operating, will continue with the previ-  
ous program's setpoint until the next program  
change.  
Any of the times can be changed by scrolling to that  
line and pressing the + or – button until the desired  
program time is displayed.  
STATISTICS  
This sub-menu provides information about system activity and  
mix valve cycle counts. See Fig. 3 on page 8 for an illustration  
of the statistical data that can be displayed.  
5
69-1979—04  
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AQUATROL ZONE SYNCHRONIZING BOILER RESET CONTROLS  
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.  
TROUBLESHOOTING  
Power Disruption  
The AQ251’s system and thermostat (zone settings)  
parameters are stored in non-volatile memory and are  
updated as they change.  
NOTE: If the power failure parameter is set to Backlight  
(USER MENU > PREFERENCES/TIME), the LCD  
backlight flashes repeatedly, along with the mes-  
sage.  
When a power disruption or loss of power occurs, the system  
configuration is retained in memory.  
The AQ251 remains permanently in OCCUPIED (or Comfort)  
mode until the DAY and TIME OF DAY are updated.  
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.  
System Status and Error Codes  
System status alerts and error messages display on the  
System Status Page. These messages are shown in Table 2.  
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.  
Table 2. LCD Status Notices and Error Messages.  
LCD Display  
A/C MIN. OFF TIME  
A/C MIN. ON TIME  
AUX IN EM. SHUT  
BOILER:  
Parameter  
n/a  
Meaning  
The A/C compressor is disabled, because the minimum OFF time has not yet elapsed.  
The A/C compressor is active and the minimum ON time has not yet elapsed.  
Auxiliary Input's Emergency Shut Down is active.  
n/a  
n/a  
EM SHUT  
FRZ PROT  
Boiler is disabled, because the AQ251 is in Emergency Shut Down mode.  
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  
IDLE  
Boiler is active to serve zones.  
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  
CALL FOR DHW  
CALL FOR HEAT  
CWSD ACTIVE  
n/a  
n/a  
n/a  
n/a  
At least one zone with a programmable thermostat requires cooling.  
The DHW requires heat.  
At least one zone requires heat.  
Zone calls for cooling are not served because CWSD (Cold Weather Shutdown) is in  
progress.  
DHW DISABLE  
n/a  
n/a  
DHW call is not served because it is disabled.  
LOST ZONE A-1  
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).  
LOST ZONE D-16  
NO DHW PROBE  
n/a  
n/a  
No DHW sensor connected or it is defective.  
No outdoor sensor connected or it is defective.  
NO OUTDOOR PROBE  
69-1979—04  
6
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AQUATROL ZONE SYNCHRONIZING BOILER RESET CONTROLS  
Table 2. LCD Status Notices and Error Messages. (Continued)  
LCD Display  
Parameter  
Meaning  
No return sensor connected or it is defective.  
NO RETURN PROBE  
NO SUPPLY PROBE  
SHORT CYCLE PROT  
n/a  
n/a  
n/a  
No supply sensor connected or it is defective.  
There is a call for heat, but less than two minutes have elapsed since the last firing of  
the boiler (prevents short cycling).  
VALVE INIT  
n/a  
n/a  
n/a  
Motorized mixing valve controlling the secondary loop is being initialized and  
repositioned (opening or closing) to meet the secondary loop target temperature.  
WATER READY  
WWSD ACTIVE  
Boiler Supply Water temperature is at or above the target temperature calculated by the  
AQ251.  
Zone calls for heat is not served because WWSD (Warm Weather Shutdown) is in  
progress.  
When an AQ thermostat is disconnected from the AQUATROL  
network, a message displays on the System Status page of  
the AQ251 indicating “Lost Zone A-xx”, where “xx” is the  
specific identity, or address, of the lost zone. This helps the  
servicing contractor quickly identify the lost zone and fix its  
wiring, to re-establish communication with the Control Module.  
When a new AQ2000 component is connected on the  
AQUATROL network, its settings are communicated to the  
AQ251's Boiler Control Module (AQ1520M0) within 10  
seconds of being connected. If the component is an AQ1000  
thermostat, the setpoints for that zone thermostat can be  
modified from the Boiler Control Module as soon as it is  
recognized by the Control Module.  
7
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AQUATROL ZONE SYNCHRONIZING BOILER RESET CONTROLS  
USER MENU STRUCTURE  
Press the Menu button on the keypad to display the User Menu. Fig. 3 illustrates all possible User Menu selections.  
USER MENU  
SYSTEM STATUS  
PREFERENCES/TIME  
ZONE SETTINGS  
PROGRAM SETTINGS  
STATISTICS  
1
SYSTEM STATUS  
PREFERENCES / TIME  
ZONE SETTINGS (All or Single)  
PROGRAM SETTINGS  
STATISTICS  
AUX IN EM.SHUT  
LAST DATA RESET: 2000 JAN 01  
MODE:  
AUTOꢁ  
BOILER UNITS:  
ZONE UNITS:  
TIME DISP:  
°Fꢁ  
°Fꢁ  
EDIT ALL ZONES  
BOILER:  
IDLEꢁ  
BOILER FIRE ACTIV:  
BOILER PUMP ACTIV:  
DHW PUMP ACTIV:  
AUX PUMP ACTIV:  
AUX OUT ACTIV:  
ZONE  
0H  
0H  
EDIT ALL DAYS  
EDIT DAILY  
EDIT SINGLE ZONE  
CALL FOR DHW  
CALL FOR HEAT  
DHW DISABLE  
12Hꢁ  
0H  
D.S.T.:  
YEAR:  
ENABLEꢁ  
2008ꢁ  
JANꢁ  
ARE YOU SURE?  
NO YES  
0H  
LOST ZONE A-1  
...  
0H  
MONTH:  
A-1ꢁ  
0H  
DATE:  
1ꢁ  
LOST ZONE D-16  
NO DHW PROBE  
ACTIV:  
DAY:  
MONDAYꢁ  
12:00Aꢁ  
DETAILꢁ  
AUTOꢁ  
ZONE  
A-1ꢁ  
TIME:  
ROOM TEMP  
NO OUTDOOR PROBE  
NO RETURN PROBE  
NO SUPPLY PROBE  
SHORT CYCLE PROT  
VALVE INIT  
HOMEPAGE:  
BACKLIGHT:  
POWER FAILURE  
FLOOR TEMP  
SETPOINT:  
2
3
70ꢁ  
70ꢁ  
EDIT ALL DAYS  
FLOOR SETPT:  
HEAT/COOL STATUS  
SETBACK:  
NOTICE:  
BACKLIGHTꢁ  
ALL WAKE  
ALL LEAVE  
ALL RETRN  
ALL SLEEP  
6:00Aꢁ  
8:00Aꢁ  
4:30Pꢁ  
10:00Pꢁ  
7ꢁ  
100ꢁ  
41ꢁ  
WATER READY  
SETPOINT MAX:  
SETPOINT MIN:  
FLOOR LIM HI:  
FLOOR LIM LO:  
SETPOINT VACANCY  
HEAT:  
WWSD ACTIVE  
ARE YOU SURE?  
NO YES  
COPY TO ALL DAYS  
100ꢁ  
41ꢁ  
COPY WAKE  
COPY LEAVE  
COPY RETRN  
COPY SLEEP  
41ꢁ  
SETPOINT VACANCY  
COOL:  
100ꢁ  
2ꢁ  
CHANGEOVER:  
EDIT DAILY  
KEYBOARD:  
UNLOCKꢁ  
MON WAKE  
MON LEAVE  
MON RETRN  
MON SLEEP  
...  
6:00Aꢁ  
8:00Aꢁ  
4:30Pꢁ  
10:00Pꢁ  
1
2
4
5
THE SYMBOLS INDICATE ADDITIONAL SELECTIONS ARE POSSIBLE.  
THE FACTORY DEFAULT VALUES ARE SHOWN.  
TEMPERATURE VALUES ARE SHOWN IN DEGREES FAHRENHEIT,  
WHICH IS THE FACTORY DEFAULT TEMPERATURE UNIT.  
SUN WAKE  
SUN LEAVE  
SUN RETRN  
SUN SLEEP  
6:00Aꢁ  
--:--  
--:--  
10:00Pꢁ  
3
4
5
EITHER HEAT OR COOL DISPLAYS DEPENDING ON THE SYSTEM’S STATUS.  
FACTORY DEFAULT TIMES FOR MON THROUGH FRI.  
FACTORY DEFAULT TIMES FOR SAT AND SUN.  
M27750  
Fig. 3. User Menu Structure.  
AQUATROL® is a registered trademark of Honeywell International Inc.  
Automation and Control Solutions  
Honeywell International Inc.  
1985 Douglas Drive North  
Golden Valley, MN 55422  
customer.honeywell.com  
Honeywell Limited-Honeywell Limitée  
35 Dynamic Drive  
Toronto, Ontario M1V 4Z9  
® U.S. Registered Trademark  
© 2009 Honeywell International Inc.  
69-1979—04 M.S. Rev. 09-09  
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