AQ251 SERIES BOILER RESET CONTROL PANELS
31 69-1974—04
BOILER SETTINGS (continued)
OUTDOOR
LOW
-60°F to 32°F (-51°C to 0°C) 10 °F
(-12°C)
The lowest annual outdoor temperature for the location
where the system is installed, also referred to as the
Design Temperature. Typically used in the original heat
loss calculations for the building, the OUTDOOR LOW
temperatures for various cities in North America can
generally be found in ASHRAE tables.
BOILER DSGN 80°F to 210°F (27°C to 99°C) 180°F
(82°C)
The supply water temperature required from the boiler
when the outdoor temperature is at the OUTDOOR LOW
temperature.
MIN. RETURN OFF / 80°F to 180°F (27°C to
82°C)
140 °F
(60°C)
Minimum temperature (or OFF) that the control allows for
water returning to the boiler.
If the temperature of the boiler return water is below the
selected temperature, and
the AUX pump is set to operate
as a boiler bypass pump (EQUIPMENT SETUP >
AUXILIARY I/O > AUX.PUMP option is set to BYPASS),
the AUX dry contacts close, allowing the separately-
powered AUX pump to energize.
BOILER OPERATION
CYCLES/HOUR 2 to 6 4 The number of heating cycles per hour that the control will
operate the boiler.
FIRE DELAY 0 seconds to 3 minutes
(in 5 second increments)
10
(seconds)
Time period that AQ251 control expects between closing
the T-T relay and the boiler firing up. Referring to the
boiler's instruction manual, set this value equal to the
boiler's pre-purge time, if available for the boiler.
PURGE TIME OFF, 10 seconds to
30 minutes
(in 10 second increments)
30
(seconds)
Length of time the Boiler pump (or Boiler pump plus zone
valve) will continue to operate (remain open) after the
boiler stops firing. Adjustable from 10 seconds to
30 minutes or OFF.
EXERCISE YES / NO YES Option can be set to YES or NO. When set to YES, all
pumps and valves in the system are energized for
30 seconds, following a period of 2 weeks of no zone
equipment activity. The boiler is not fired during this
operation.
FREEZE PROT YES / NO YES Option can be set to YES or NO. When set to YES, all
pumps and valves in the system are energized for
4 minutes every hour. The boiler is operated at high fire
during this operation.
10V MOD. SELECT Operating settings for the analog 0-10V (2-10V) modulating signal
10V MOD 0-10V / 2-10V 0-10V The analog signal provided by the control to the mixing
valve or variable speed pump is proportional to the degree
of opening of the valve or the speed of the pump. It is
opened fully at 10V and closed fully at either 0V or 2V,
depending on the setting chosen. The pump is running at
maximum speed at 10V and completely stopped at 0V or
2V.
USAGE NONE / BOILER NONE This setting assigns the device which the analog signal will
drive. The NONE option disables a signal from the 10V
output.
Table 6. Installer Menu – Equipment Setup. (Continued)
EQUIPMENT SETUP
Menu Option Range
Factory
Default Description
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