6 PURGE AIR FROM ALL SYSTEM
AND ZONE PIPING
Purging air from all zones in the hydronic system is easily
accomplished with the AQ250 by using a modification to the
Auto Test feature (described in "Auto Test" on page 17) as
• To purge all zones on the AQUATROL network press the
Test button on the AQ15000B Control Module once to begin
the Auto Test routine. Quickly press it again 3 times until the
Boiler relay LED illuminates and the Diagnostic LED of the
AQ15000B blinks slowly (which indicates the Auto Test
routine has been paused). The boiler pump now remains
energized for the duration of the Purge routine (and
therefore can be purging all loops of air) until the Test button
is pressed again.
• The Diagnostic LED blinks slowly while in paused mode.
Continue to purge the boiler loop as long as is needed to
remove air from the system.
• Leaving the boiler pump operating, push the Test button on
the Zoning Module for any space heating zones you wish to
• With the first zone's output energized (the LED for
Zone 1 illuminates), press the Test button again to
pause the Auto Test routine.
• When Zone 1 has been sufficiently purged, press
the Test button again to begin purging Zone 2.
• Again, press the Test button to pause the Auto Test
routine while purging Zone 2.
• Continue to purge all other space heating zones in
If additional purging is required for any zone, the Auto Test
procedure can be activated for any individual Zoning Module
by pressing the Test button located above that Zoning
Module's DIP switches. Refer to "B) Auto Test– AQ155/AQ157
Zoning Modules" on page 17.
7 DOCUMENT AND KEEP A RECORD
OF ALL SYSTEM SETTINGS
After the AQ250 Series Control Panel and any AQ255/AQ257
Expansion Zoning Panels have been set up and the entire
hydronic installation is operating properly, it is important to
document all the system settings for future reference.
All AQ2000 Series Panels are shipped with Installation Job
for documenting these settings.These should be
filled out completely and saved in the Installing Contractor's
For the AQ250 Series, refer to AQ25042B RelayPLUS Zone
Synchronizing Boiler Control, (form 69-1972) and AQ25044B
RelayPLUS Zone Synchronizing Boiler Control (form 69-
AQ250 SERIES HYDRONIC CONTROL PANELS
The following information helps the installer correctly identify
system problems, making troubleshooting much faster. Table 4
and Table 5 on page 20 describe the possible error codes that
can be communicated on the diagnostic LEDs of the
AQ15000B Control Module and AQ155/AQ157 Zoning Module.
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
AQ250 would be loss of communication between the
AQ15000B 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
CONTROL MODULE REACTION
When the AQ15000B 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 AQ250 continues to deliver heat to
the other non-communicating zones.
When communication is lost with all zones, the AQ250 enters
Freeze Protection mode, in which it fires the boiler and then
activates the Boiler (supply) pump and zone equipment for a
period of 4 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
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 AQ15000B
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 one of its thermostats, that zone
is invisible to the Control Module, and the Zoning Module stops
serving that zone and the zone's pump or valve is de-
The AQ250 provides Zoning Module diagnostic information via
the Diagnostic LED located above the DIP switches on each