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3.5
BURNER
Figure 24: Valiant FT Series II Burner
This appliance uses a single cylindrical burner installed
vertically into the combustion chamber at the top of the heat
exchanger. The burner consists of a round mounting flange
welded to a mixing tube. The flange provides the transition
from the combustion air fan into the burner. The mixing tube
is covered with a knitted alloy material that forms the burner
port surface. The burner port surface can sustain operation
from a blue flame down to infrared conditions as the burner
input varies.
There is a unique burner for each model. Burners may not
be interchanged between different input models.
3.6
SPARK IGNITER
Figure 25: Spark Igniter
The ceramic igniter is inserted directly through the fan
flange and held in place by two screws. A sealing gasket
above and below the igniter assures a good seal. The
igniter provides the spark which ignites the main burner
flame during start-up.
3.7
FLAME SENSOR
The flame sensor is inserted directly through the fan flange
and is screwed into the fan flange. Care must be taken
when installing the flame sensor to align it perpendicular to
the fan flange and parallel to the burner tube and not to over
tighten. Always remove the flame sensor prior to removing
the fan assembly for inspection of the burner and heat
exchanger.
Figure 26: Flame Sensor
The ignition module relies on the flame sensor to provide a
flame rectification signal. Oxide deposits, improper
placement or damaged ceramic insulator will result in
insufficient signal leading to ignition module lock out. For
proper operation minimum 0.8 VDC must be fed back to the
module. Oxide deposit on the sensor rod must be removed
with steel-wool. Do not use sand-paper since this will
contaminate the surface.
PART 4
OPERATION & START UP
4.1
SEQUENCE OF OPERATION
Figure 27: Valiant-FT Series II Ignition Cycle
Supply power connection as per 2.5.1 'Minimum
1.
Power Requirements'.
Place power switch in the "ON" position.
2.
3.
120 VAC power is supplied to the control
transformer.
4.
24 VAC is supplied to the ignition module and low
voltage controls.
5.
The Valiant FT Series II controller receives a call
for heat via the remote operator contacts and the
Demand parameter reads Central Heating,
DHW, or Lead Lag Slave.
6.
The Valiant FT Series II controller closes the
pump contacts to start the pump, which then
causes the Flow Switch to close once minimum
flow is reached. If all limit controls are made
including temperature and water flow, the
controller closes the blower contacts to ramp up
the frequency of the Combustion Fan using the
modulating signal provided by the on-board
modulating control. If the Low Air Switch contacts
are made within the 60 seconds, the blower will
run at Pre-Purge speed until the Pre-Purge timer
is satisfied.
7.
After the appliance water pump starts, flow is
proven by the Flow Switch. The Flow Switch is
mounted at the outlet of the appliance. If
installing a Flow Switch, it is required to properly
trim the Flow Switch Paddles in order not to jam
the switch in the tee.
8.
Once the Pre-Purge Timer is satisfied, the
Valiant FT Series II controller will target the
ignition fan speed.
9.
The Valiant FT Series II controller will activate the
Spark Ignitor for a few seconds before energizing
the gas valve. A signal of 0.8 Vdc minimum must
be recognized by the controller at the Flame
Sensing rod (or at the UV Scanner if equipped)
14
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