CleaverBrooks FLX Operation, Service And Parts Manual page 32

Chapter 2
Return the setpoint to its original position before pro-
ceeding.
6. Shut off the combustion air blower. This should cause a
failure due to low air pressure and cause the safety
valves to close.
7. Reset all manual valves to their normal setting for oper-
ation. Make sure all electric valves are operating nor-
mally. Make sure all test cocks are closed before
resuming normal operation.
8. Close the downstream main and pilot gas cocks. Make
sure the ON-OFF switch is in the OFF position. Actuate
the manual reset button of the flame safeguard control to
close the safety switch contacts.
For LOW-HIGH-OFF or LOW-HIGH-LOW and FULL
MODULATION models, set the MANUAL-AUTO
switch to the MANUAL position.
9. Set the manual potentiometer to low-fire position.
10. Open the gas pilot cock. Check pressure. Normal setting
is 4" to 6" WC when the pilot is burning.
11. Set the ON-OFF switch to ON. The burner will start and
pre-purge. After pre-purge, the ignition transformer and
the gas pilot solenoid are energized.
On initial startup it is recommended that the main gas
shutoff cock remain closed until the programmer has
cycled through pre-purge and pilot sequence. Then
determine that the main gas valve opens. When this is
confirmed, turn the burner switch OFF and let the pro-
grammer finish its cycle. Check to see that the gas valve
has closed tightly.
If ignition does not occur, turn the burner switch OFF
and allow the programmer to recycle for a new ignition
trial.
12. Turn the burner ON and after pilot ignition when the
flame relay pulls in, the slow opening, motorized, main
gas valve is energized. Slowly open the downstream
manual shutoff gas cock. Main flame should ignite at
this time. The gas valve and air damper continue
advancing until high-fire is reached.
13. Do not repeat unsuccessful light off attempts without
rechecking burner and pilot adjustment. Vent fuel
vapors from the combustion chamber after each unsuc-
cessful light off attempt. Set the gas low-fire rate by
adjusting butterfly valve and air linkage. Refer to the
adjustment section of this manual. Using the combus-
tion analysis instrument, adjust the low-fire. Typical
combustion analysis for low-fire it 5% to 6% O2 on
standard turndown systems, and between 6.5% and 9%
for higher turndown systems. Verify the minimum input
rate by measuring the gas meter.
2-20
14. When low-fire is adjusted, shut down the burner. Restart
several times to be sure the low-fire setting is suitable.
Readjust if necessary. Never start the burner with fuel
vapor in the furnace. In case of emergency, open main
power switches and close all fuel valves. After combus-
tion adjustments are satisfactorily set, allow the heating
vessel to slowly reach normal operating pressure or tem-
perature.
15. After the boiler has reached operating temperature or
pressure, turn the potentiometer switch in small incre-
ments to the high-fire position. Check high-fire at this
point using combustion instruments. High-fire combus-
tion analysis typically 3% to 4% O2. Verify maximum
input rate by measuring the gas meter.
16. Do not disturb established low-fire adjustment. Allow
the burner to return to low-fire position before adjusting
high or intermediate settings. CO levels should be less
than 400 ppm on an air-free basis at all firing rates with
<50 ppm as the target value.
When conditions covered above are assured, refer to Sections
F and G.
OIL BURNERS:
1. The fuel selector switch should be set to OIL and the
ON-OFF switch should be in the OFF position. Actuate
the manual reset button of the flame safeguard control to
close the safety switch contacts.
2. Set the ON-OFF switch to ON. The burner will start and
pre-purge. After pre-purge, the ignition transformer will
direct spark. If the flame detector proves the presence of
a satisfactory pilot, the programmer will proceed to
main flame ignition.
3. Make initial air shutter setting for smooth ignition.
Return line oil pressure should be set according to Sec-
tion 4 - ADJUSTMENTS. Do not repeat unsuccessful
light off attempts without rechecking burner and pilot
adjustment. Vent fuel vapors from the combustion
chamber after each unsuccessful light off attempt. Set
the oil low-fire rate by adjusting the oil return pressure
and air linkage. Refer to the adjustment section. Using
the combustion analysis instrument, adjust the low-fire.
Typical combustion analysis for low-fire is 5% to 6%
O2.
4. When low-fire is adjusted, shut down the burner. Restart
several times to be sure the low-fire setting is suitable.
Readjust if necessary. Never start the burner with fuel
vapor in the furnace. In case of emergency, open main
power switches and close all fuel valves. After combus-
tion adjustments are satisfactorily set, allow the heating
vessel to slowly reach normal operating pressure or tem-
Profire V Burner
750-177