Installation / Operation Instruction Manual

Addendum H2381401- to Brute LX 1295A
Document 1372
H2381401-
The 14 updated pages of document 1295A. The Brute LX (Series 1, wall only) Installation and Operating Manual.
Page 36
BRADFORD WHITE CORP .
8.6 Modulation Control
The control uses a PID algorithm to adjust the ring
rate of the boiler as the control point is approached. The
goal of the control is to operate at a minimum ring
rate to match the load on the appliance.
8.7 Pump Control
The boiler pump is active anytime there is a call for
heat applied to the control. When there is a central heat
call the system pump relay is active. If there is a DHW
call while the central heat call is active the system
pump turns off. This happens because of domestic hot
water priority, which forces the control to satisfy the
domestic water demand prior to the hydronic demand.
When the last heat demand is satised the boiler pump
enters an overrun time.
8.8 High Limit
The control uses a dual thermistor sensor to monitor
the Brute LX's maximum temperature. The high limit
sensor is installed in the outlet water. A dual thermistor
sensor is used, so that the two temperatures can be
monitored and compared to conrm accuracy. The
control will automatically reduce the ring of the Brute
LX to prevent the high limit from tripping. The high
limit setpoint is not adjustable.
8.9 Stack Temperature
The stack temperature is a dual thermistor sensor
and is limit rated. The control compares each of the
temperature readings to determine accuracy. The stack
sensor is used as a limiting feature to avoid excessive
temperatures in the venting.
8.10 Domestic Hot Water Temperature
The domestic hot water temperature sensor is used to
control the DHW temperature. The DHW setpoint can
be adjusted through the Base / Home state and the User
Mode. On LX ‘C’ or Combi models, the DHW sensor
is pre-installed in the DHW exchanger. On LX ‘H’ or
Heat models the DHW can be can be controlled by an
aquastat or optional DHW sensor installed in an indirect
tank.
SECTION 9.
OPERATION Modes
To access the setup parameters for conguring different
Operation Modes, the installer level password most be
used according to section 8.4.
9.1 Hydronic Heating Demand
When using the Brute LX for hydronic heating a call
for heat must be supplied to the "T-T or Interlock"
terminals. Once the call is supplied the control
energizes the boiler pump, the system pump relay,
shifts the 3-way valve position and begins the ignition
process. The ignition process consists of a prepurge,
trial for ignition, and run period. The prepurge period
starts once the fan RPM reaches a preset level. The trial
for ignition period follows. The trial for ignition period
lasts 4 seconds during which the direct spark ignition
system and gas valve are energized. At the end of the
trial for ignition period the ame signal is compared
with the preset ame threshold value. If the ame
signal is higher than the ame threshold the Brute LX
enters "run". If the ame signal is below the threshold
the Brute LX returns to prepurge and starts the ignition
process over. In "run" the Brute LX monitors the ame
signal, call for heat, safeties, and water temperatures
and modulates as needed between 100% and 20% of
rate to satisfy the call for heat.
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