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move from closed to a low flow position after proving
main flame.
NOTE: If the burner is not operating as indicated, follow
the troubleshooting guide steps to determine the problem
and corrections required.
n. After a few seconds, the combustion analyzer should
have an accurate reading of the O2 in the stack. Figure
F-3 shows the typical range of O2 at different firing rates,
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 O2 level.
• Turning the cam screw out will reduce the fuel input,
increasing the O2 level.
If equipped with FGR, the NOx level should be close to
the desired NOx, as required by the specific order. The
FGR valve can be opened to decrease the NOx level, or
closed to increase the NOx level.
o. Operate the burner until the boiler is warmed up, and
near the operating pressure or temperature. Increase the
firing rate, using the manual potentiometer, while monitor-
ing and adjusting the O2 level. Adjust the gas pressure
regulator as needed to reach the high fire input.
p. If equipped with FGR, adjust the FGR valve as
needed to obtain the approximate NOx level.
q. Adjust the high fire input to match the maximum input
listed on the rating label. At high fire, the gas butterfly
valve should be at least 50 degree open (more if avail-
able gas pressure is low), and the gas pressure regulator
adjusted to obtain the rating. The input should be
measured using the following equation:
Calculating Natural Gas Input
HHV x [(Patm + Pgas)/29.92] x [520/(Tgas +460)] x
[measured ft3/sec] x [3600 sec/hr]
Where:
MBH = 1000's of BTU/M input
HHV = Higher heating value of gas, BTU/cubic feet
Patm = Atmospheric pressure in inches Hg
Pgas = Gas pressure before gas meter in inches Hg
(inches HG = PSIG x 2.04)
Tgas = Gas temperature at the flow meter, in
degrees F
Measured ft3 = volume of gas measured by meter
sec = Time for measured ft3 to flow through meter
Note: Some gas meters require a 6 inch wc correction
to Pgas. Consult your meter calibration data.
NOTE: The listed manifold pressure is only an
approximate value and can vary with operating
conditions and normal tolerances. The fuel flow rate
must be measured to obtain an accurate input value.
r. Adjust the air damper to obtain the correct O2 level.
s. If equipped with FGR, adjust the NOx level to be
JBE(X) Manual
Gas MBH =
about 10% below any guaranteed NOx performance.
A balance of the FGR control valve and air damper are
required to obtain the final result, as each can impact
the other. If the FGR valve does not travel at least 50
degrees, the FGR inlet tube should be readjusted
(pushed into the FGR pipe).
t. Modulate the burner to low fire, adjusting the O2 level
as the burner modulates.
u. Adjust the low fire input, using the fuel cam and air
damper adjustments. The linkage may need to be read-
justed to obtain the correct relationship between the fuel
valve and air damper. (Figure F-1)
v. Re-adjust the midfire points for the correct O2 level.
w. If equipped with FGR, adjust the NOx levels at low
and midfire rates to be about 10% under the guaranteed
levels.
x. Adjust the low gas pressure switch to be 10% below
the lowest expected gas pressure.
• With a gauge or manometer at the same location as
the low gas pressure switch, modulate the burner to
determine the firing rate with the lowest gas pressure.
• At the lowest gas pressure,adjust the low gas pressure
setting up until the switch breaks and causes the burner
to shutdown.
• From the scale reading of the switch, adjust the
setting to a pressure that is 10% lower than the shut-
down pressure. For example, if the switch opened at 10
inches as indicated on the low gas pressure switch, the
switch should be adjusted to a reading of 9 inches.
• Remove the gauge/manometer and plug the opening.
• Cycle the burner on and off to determine if the limit
works properly.
• If the limit causes nuisance shutdowns because of
small pressure drops during startup, reduce the pres-
sure setting an additional 5%.
y. Adjust the high gas pressure switch to be 10% above
the highest expected gas pressure.
• With a gauge or manometer at the same location as
the high gas pressure switch, modulate the burner to
determine the firing rate with the highest gas pressure.
• At the highest gas pressure, adjust the high gas
pressure setting down until the switch opens and causes
the burner to shutdown.
• From the scale reading of the switch, adjust the setting
to a pressure that is 10% higher then the shutdown
pressure. For example, if the switch opened at 10 inches
as indicated on the high gas pressure switch, the switch
should be adjusted to a reading of 11 inches.
• Remove the gauge/manometer and plug the opening.
• Cycle the burner on and off to determine if the limit
works properly.
• If the limit causes nuisance shutdowns because of
small pressure changes during startup, increase the
pressure setting an additional 5%.
z. The burner should be operating at low fire to adjust
the air proving switch. Turn the adjusting screw cw (in)
until the burner trips out (shutdown caused by the air
flow switch). Turn the adjustment screw ccw (out) 1 1/2
turns from the point of shutdown. Check the operation at
higher rates.
Page 44
Section F - Startup and Operating Instructions
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