Troubleshooting - Honeywell AQ25A Series Technical Reference Booklet

• FACTORY settings are the default values loaded at the
factory and are the starting point for programming the
AQ252. These values are permanently stored in memory
and cannot be over-written or erased. The AQ252 can be
restored to factory settings through the RESTORE
FACTORY option in the SAVE / RESTORE sub-menu. A
warning prompt, RESTORE FACTORY—ARE YOU
SURE?, displays and YES or NO must be chosen before
proceeding. If YES is selected, the FACTORY settings are
be copied to the AQ252's CURRENT settings and the
Control Panel begins to operate with these values
immediately.
• SETUP settings are the specific settings for this installation
which an installer has saved after the AQ252 is set up and
operating well. These are saved for future recall, in case the
system's settings are inadvertently changed.
— To save this installation's settings for the first time, go to
the EQUIPMENT SETUP > SAVE/RESTORE sub-
menu. Position the indicator arrow (←) beside SAVE
SETUP and press OK. This saves the current system
settings to the SETUP values.
— To retrieve the SETUP values at any time in the future,
go to the EQUIPMENT SETUP > SAVE/RESTORE
sub-menu and select RESTORE SETUP to load those
values into the AQ252 as the CURRENT settings. The
system will now operate according to these retrieved
settings.
— If the current settings are modified after a RESTORE
SETUP operation is performed, simply select SAVE
SETUP again to overwrite these new settings into the
SAVE settings memory.
CAUTION
If you change any system settings after a
RESTORE SETUP operation, you change the
current settings that the AQ252 uses as its basis of
operation.

TROUBLESHOOTING

The following information helps the installer correctly identify
system problems, making troubleshooting much faster.
Table 3 and Table 4, beginning on page 22, describe the
possible error codes and status notices that can be
communicated on the AQ155 / AQ157 Zoning Modules'
diagnostic LEDs.
System Status Information
To aid in troubleshooting hydronic systems controlled by an
AQ252, the operational status of the system is shown on the
System Status page. Status notices and error messages
display here as appropriate, i.e., only those that are pertinent
to the system's current operation will be displayed. See Table 4
on page 22 for a complete list of status notices and error
messages. The System Status page is available from the User
Menu.
When a new AQ2000 component is connected on the
AQUATROL network, its settings are communicated to the
AQ252 Control Module within 10 seconds of being connected.
If the component is an AQ1000 thermostat, the setpoints for
that zone thermostat can be modified from the AQ252 Control
Module as soon as it is recognized.
AQ252 Universal Injection/Mixing Boiler Reset Control Panels
When an AQ1000 thermostat is disconnected from the
AQUATROL network, a message displays on the System
Status page of the AQ252 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 AQ252
Control Module.
This diagnostic information is very valuable and the System
Status page is the first place a contractor should look for
information when troubleshooting system problems.
Communications Loss
Because all AQ2000 Series components communicate with
each other via the dedicated AQUATROL network when
controlling a hydronic system, one possible failure mode of the
AQ252 would be loss of communication between the AQ1520
Control Module and any connected Zoning Modules, or
between a Zoning Module and any zone thermostats
connected to the AQUATROL network. In general, the Control
Module:
• Periodically tries to re-establish communication with any
lost components on the network.
• Initializes any component that re-establishes its
communication.
• Displays an error code on the AQ252's System Status page,
until the error is corrected and/or communication is re-
established.
CONTROL MODULE REACTION
When the AQ1520 Control Module loses communication with
any number of zones for more than one minute (as long as
there is still at least one zone communicating on the
AQUATROL network), the AQ252 continues to deliver heat to
the other non-communicating zones. The address of each lost
zone (e.g., A-7, B-4) displays on the System Status page.
When communication is lost with all zones, the AQ252 enters
BOILER FREEZE PROTECTION mode, in which it fires the
boiler and then activates the Boiler (supply) pump and zone
equipment for a period of 10 minutes every hour. This should
provide sufficient heat to the system to prevent a building from
freezing up until communication is re-established between the
AQ2000 Series components.
BOILER FREEZE PROTECTION mode is disabled when the
outdoor temperature is above the warm weather shutdown
(WWSD) temperature setting.
ZONING MODULE REACTION
When a Zoning Module loses communication with the Control
Module (as long as there is at least one other Zoning Module
communicating with the Control Module), the Zoning Module
operates its pumps or valves in a conventional, non-
synchronized zoning fashion. That is, it operates according to
the demands from the thermostats, without zone
synchronization or waiting for permission from the AQ152
Control Module to operate. This allows the zones to extract any
heat provided by the boiler.
When using AQ1000 thermostats and communication is lost
between a Zoning Module and any of its thermostats, that zone
enters Single Zone Freeze Protection mode. In this mode, the
zoning equipment is operated for an amount of time equal to
one-half of the maximum demand of all other zones on the
network. This helps prevent the lost zone from freezing. This is
especially helpful if a zone's thermostat is removed from the
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