Page 48
10−Gas Valves GV1 and GV3
Gas valves GV1 and GV3 are identical. The gas valves are
two-stage redundant valves. Units are equipped with valves
manufactured by White−Rodgers or Honeywell. For both
valves first stage (low fire) is quick opening (on and off in less
than 3 seconds). Second stage on the White−Rodgers is slow
opening (on to high fire pressure in 40 seconds and off to low
fire pressure in 30 seconds). Second stage on the Honeywell
valve is quick opening. On a call for first stage heat (low fire),
the valve is energized by the ignition control simultaneously
with the spark electrode. On a call for second stage heat (high
fire), the second stage operator is energized directly from A55
(GV1) and A58 (GV3). The White−Rodgers valve is adjust-
able for high fire only. The Honeywell valve is adjustable
for both low fire and high fire. A manual shut−off knob is
provided on the valve for shut−off. Manual shut-off knob
immediately closes both stages without delay. Figure 25
shows White−Rodgers gas valve components. Table 4
shows factory gas valve regulation for LGA/LGC series
units. See Page 7 for high altitude operating pressures.
FIGURE 25
LOW FIRE
ADJUSTMENT
HIGH FIRE
ADJUSTMENT
INLET
PRESSURE
TAP
MANIFOLD
PRESSURE
TAP
HONEYWELL VR8305/VR8205 GAS VALVE
GAS VALVE SHOWN
IN OFF" POSITION
WHITE−RODGERS 36C76 GAS VALVE
D−1
GV−1
C−1
C2
GV−2
MANIFOLD
PRESSURE
TAP (SIDE)
STAGE 2 MANUAL MANIFOLD
PRESSURE ADJUSTMENT
SCREW UNDER CAP
INLET
PRESSURE
TAP (SIDE)
GAS VALVE
SHOWN IN OFF"
POSITION
TABLE 4
GAS VALVE REGULATION FOR LGA/LGC UNITS
Operating Pressure
(outlet) Factory Setting
Natural
L.P.
3.7+0.3"W.C.
920+
75Pa
Low
High
Low
High
1.6+0.2"W.C.
398+
50Pa
10.5+
0.5"W.C.
2611+
125Pa
5.5+
0.3"W.C.
1368+
75Pa
11−Spark Electrodes
An electrode assembly is used for ignition spark. Two
identical electrodes are used (one for each gas heat
section). The electrode is mounted through holes on the
left-most end of the burner support. The electrode tip
protrudes into the flame envelope of the adjacent burner.
The electrode assembly is fastened to burner supports and
can be removed for service without removing any part of the
burners.
During ignition, spark travels through the spark electrode (fig-
ure 26) and ignites the left burner. Flame travels from burner to
burner until all are lit.
The spark electrode is connected to the ignition control by a 8
mm silicone-insulated stranded high voltage wire. The wire
uses 1/4" (6.35 mm)female quick connect on the electrode
end and female spark plug−type terminal on the ignition control
end.
NOTE−IN ORDER TO MAXIMIZE SPARK ENERGY TO
ELECTRODE, HIGH VOLTAGE WIRE SHOULD TOUCH
UNIT CABINET AS LITTLE AS POSSIBLE.
GROUND
ELECTRODE
GROUND
ELECTRODE
.125" ± .015"
(3.2 mm ± .4 mm)
FIGURE 26
12−Flame Sensors
A flame sensor is located on the right side of each burner
support. The sensor is mounted through a hole in the burn-
er support and the tip protrudes into the flame envelope of the
right most burner. The sensor assembly is fastened to burner
supports and can be removed for service without removing
any part of the burners. When flame is sensed by the flame
sensor (indicated by microamp signal through the flame)
sparking stops immediately. During operation, flame is
sensed by current passed along the ground electrode (lo-
cated on the spark electrode), through the flame and into
the sensing electrode. The ignition control allows the gas
valve to stay open as long as a flame signal (current
passed through the flame) is sensed.
FIGURE 27
SENSOR
To Next Page
Loading...
Need help?
General
