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2. Linkage Adjustments
Adjusting the air damper on a linkage system requires an
understanding of linkage setups. The rate of change for
the fuel valve and air damper must be matched by how
the linkage is set up. If the air damper opens too quickly,
the flame may become unstable. There are a few general
guidelines that should be followed in setting up the linkage
of a burner,
a. The linkage must provide the correct stroke of the
valve, from low to high fire. Increasing the length of the
drive crank arm (B) or decreasing the length of the driven
crank arm (C) will increase the valve travel. To reduce
valve travel, decrease B or increase C (Figure I-1).
b. Decreasing the angle of the drive arm will slow the initial
valve travel (and speed up the travel at high fire). This
would be done to get the air damper to match the fuel
valve action.
Low
Fire
Modulating
o
Range 90
High
Fire
Linkage Arm
Dim
Smaller
Angle A
Slower LF driven
arm travel (D)
Length B
Reduce driven
arm travel (D)
Length C
Increase driven
arm travel (D)
Linkage Adjustments
SG Manual
A
Drive Arm
B
Jackshaft
D
Driven
Arm
Valve
(Air Damper)
C
Larger
Faster LF driven
arm travel (D)
Increase driven
arm travel (D)
Reduce driven
arm travel (D)
Figure I-1
3. Gas Setup
a. Place the burner switch in the "OFF" position
b. Place the "Auto-Manual" switch in the manual position,
for modulation or low fire hold, switch in low fire position
for Lo-Hi-Lo operation. If this is a combination fuel burner,
make sure the fuel selector switch is on "GAS".
c. Place the manual flame control potentiometer in the
MIN (low fire) position on modulating units.
d. Close the downstream manual shutoff valve (closest to
the burner head) on the gas train.
e. Turn the electrical power on for the burner, boiler and
related components.
f. Verify that the gas metering valve is nearly closed and
the vent valve (if equipped) is operating.
g. Turn the burner switch on. This will start the blower
motor and initiate the prepurge cycle.
h. When the pre-purge sequence is complete and the low
fire start switch (if used) is made, the gas valve will open
and the flame should be visible through the sight port.
i. After the timer has completed the trial for main flame,
the burner will go out on alarm (the closed manual gas
valve prevented the burner from lighting). At this time, the
gas valves must be visually checked to verify that they
have closed. This test sequence proves the proper op-
eration of the primary control.
j. Press the reset button and restart the burner. When the
pilot has started, open the manual gas valve to allow the
main flame to start.
k. After a few seconds, the combustion analyzer should
have an accurate reading of the O
1-3 shows the typical range of O
and the burner should be adjusted to be within this range.
Rough settings for low and mid fire combustion settings
are adequate at this time. Once the high fire is set, the
other settings can be fine tuned.
• Turning the cam screw in will add fuel, making it richer
and reducing the O
• Turning the cam screw out will reduce the fuel input,
increasing the O
l. Operate the burner until the boiler is warmed up, and
near the operating pressure or temperature. Increase the
firing rate, using the manual potentiometer, or put low fire
hold switch in auto mode, while monitoring and adjusting
the O
level. Adjust the gas pressure regulator as needed
2
to reach the high fire input.
Page 13
in the stack. Figure
2
at different firing rates,
2v
level.
2
level.
2
Startup and Operating Adjustments
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