CleaverBrooks FLX Operation, Service And Parts Manual page 41

Profire V Burner
Allow the boiler to fully warm up before making adjustments
for most efficient combustion. Refer to the boiler instruction
manual for the boiler controls settings.
GAS BURNERS
The gas burners adjustments on a full modulation burner
consist of the gas pressure regulator, butterfly gas valve, low
and high gas pressure switches (Model V30-168), and air
dampers.
1. Open the manual gas shutoff cocks.
2. Check the gas pressure at the inlet of the regulator and
the pressure downstream of the regulator. Make sure
they are in accordance with the regulator specifications.
The gas pressure required at the manifold is the pressure
that is required to fire the burner at its rated capacity. To
adjust the regulator, unscrew the cap located on top and
turn the adjustment screw clockwise to increase pres-
sure, or counterclockwise to decrease pressure.
3. Set the Manual-Auto switch on the "Manual" position.
4. Position the manual flame control potentiometer in the
CLOSED (low-fire) position.
5. Turn the burner switch to the "On" position.
6. The burner will start and be in the low-fire position.
7. After a few seconds, the O
accurate reading of the O
mally, O levels are set between 4% to 6% at low-fire
2
for standard turndown systems on gas and 6% to 9% O
for high turndown systems, with the target value of less
than 50 ppm CO. To obtain the proper readings, adjust
the gas butterfly opening and air shutters. Take note of
the readings and pressures at the burner manifold and
gas train.
8. Operate the boiler at low-fire until it is up to operating
pressure (steam) or temperature (hot water). Then
increase the fuel input to the boiler by turning the man-
ual flame control potentiometer towards OPEN in small
increments. This will cause the butterfly valve to open,
allowing more gas into the burner.
9. At each point, allow the burner to operate for a few min-
utes before recording the O
Observe that the O and CO levels remain within an
2
acceptable limit. Adjust the pressure regulator as neces-
sary, to correct this situation. Continue to do this until
the burner reaches high-fire (the potentiometer is at the
OPEN position).
10. Adjust the high-fire gas input to match maximum rating.
At high-fire, the butterfly valve should be near the full
open position. Adjust the gas regulator so the manifold
pressure matches the rating on the burner data plate.
Verify and record the readings and pressures. High-fire
is typically 3% to 4% O
750-177
analyzer should have an
2
present in the flue gas. Nor-
2
, CO, and pressure readings.
2
with less than 50 ppm CO as a
2
target value.
11. Modulate the burner to low-fire. Verify the readings.
The burner should be adjusted to provide correct fuel flow at
a constant rate, at the low-fire and high-fire position as
indicated on the burner data plate. This is achieved by
clocking the gas flow at the gas meter. The gas utility or gas
meter calibration data, should be consulted to determine the
correction factors to be applied to the meter.
Natural Gas Input Calculation Using a Meter
HHV = higher heating value of gas, Btu/ft
available, use 1000)
CF = cubic feet of gas clocked
t = gas meter clock time, seconds
Pm = meter upstream pressure (see Pref for units)
Pb = barometric pressure (see Pref for units)
Pref = 14.696 psi, or 29.92 "HG, or 406.77" W.C.
Tref = gas reference temperature, ºF (use 77 if data
unavailable)
Tg = gas temperature at meter, ºF
12. Adjust the low and high gas pressure switches by turn-
ing the adjusting screw until indicator moves to a pres-
2
sure slightly lower than normal operating pressure for
the low gas pressure switch, and slightly higher for the
high gas pressure switch (usually 50% below and 50%
higher than normal pressure, respectively).
13. Tighten all linkages and marked settings. Complete the
Startup report at the end of this section.
14. Turn the Manual-Auto switch to "Auto." The burner
will now modulate according to the load demand to the
boiler.
BURNERS EQUIPPED WITH OPTIONAL FGR
VALVE FOR LOW NOx APPLICATIONS
LNV burners are equipped with an FGR (flue gas
recirculation) valve to lower the NOx emissions. An
adjustable cam is provided to adjust the FGR valve position
throughout the firing range on gas. Follow the steps for gas
above with the following additions:
1. Make sure the FGR valve is in the near closed position.
2. Start the burner up and hold at low-fire until the boiler is
at the proper operating pressure or temperature.
3. With an analyzer in the stack, adjust the FGR valve cam
screw to obtain sub 30 ppm NOx levels. DO NOT
ADJUST BURNER BELOW 20 PPM. UNSTABLE
Chapter 2
3
(if no data is
2-29