CB780E/CB784E RELAY MODULES WITH VALVE PROVING
32-00150—03
38
750-234
14.
If the main burner flame is not established after two
attempts:
a. Check for improper pilot size.
b. Check for excess combustion air at low fire.
c. Check for adequate low fire fuel flow.
d. Check for proper gas supply pressure.
e. Check for proper valve operation.
f.
Check for proper pilot flame positioning.
15.
Repeat steps 10 through 14 to establish the main
burner flame; then proceed to step 16.
16.
With the sequence in RUN, make burner adjust-
ments for flame stability and Btu input rating.
17.
Shut down the system by opening the burner switch
or by lowering the set point of the operating control-
ler. Make sure the main flame goes out. There may
be a delay due to gas trapped between the valve(s)
and burner. Make sure all automatic fuel valve(s)
close.
18.
Restart the system by closing the burner switch
and/or raising the set point of the operating control-
ler. Observe that the pilot is established during
PILOT IGN and the main burner flame is established
during MAIN IGN within the normal lightoff time.
19.
Measure the flame signal. Continue to check for the
proper signal, see
Table , through the RUN period.
Check the signal at both High and Low Firing Rate
positions and while modulating.
20.
Run the burner through another sequence, observ-
ing the flame signal for:
a. Pilot flame alone (DSI).
b. Pilot and main flame together.
c. Main flame alone (unless monitoring an inter-
mittent pilot). Also observe the time it takes to
light the main flame. Ignition of main flame
should be smooth.
21.
Make sure all readings are in the required ranges
before proceeding.
22.
Return the system to normal operation.
NOTE:
After completing these tests, open the master
switch and remove all test jumpers from the sub-
base terminals, limits/controls or switches.
Initial Lightoff Check for Direct
Spark Ignition
This check applies to gas and oil burners not using a pilot.
It should immediately follow the preliminary inspection.
Refer to the appropriate sample block diagram of field
wiring for the ignition transformer and fuel valve(s)
hookup.
NOTE:
Low fuel pressure limits, if used, could be open. If
so, bypass them with jumpers during this check.
1.
Open the master switch.
2.
Complete the normal
ready-to-fire
checkout of the
fuel supply and equipment as recommended by the
equipment manufacturer.
3.
Close all manual main fuel shutoff valve(s). Check
that the automatic fuel valve(s) are closed. Make
sure fuel is not entering the combustion chamber.
4.
Close the master switch and start the system with a
call for heat
by raising the setpoint of the operating
controller, see Fig. 8 and 9 for CB780E/CB784E
sequence. The program sequence should start the
ten second INITIATE sequence.
5.
Let the sequence advance through PREPURGE.
Ignition spark should occur after PREPURGE period.
Listen for the click of the first stage fuel solenoid
valve(s).
6.
Let the program sequence complete its cycle.
7.
Open the manual fuel shutoff valve(s).
8.
Push the reset button and recycle the program
sequence through PREPURGE.
9.
When PILOT IGN status is displayed, watch that the
first stage burner flame is established. If it is estab-
lished, proceed to step 15.
10.
If the first stage burner flame is not established
within ten seconds, close the manual fuel shutoff
valve(s), and open the master switch after POST-
PURGE is completed.
11.
Check all burner adjustments.
12.
Wait about three minutes. Close the master switch,
open the manual fuel shutoff valve(s), and try to
lightoff the burner again. The first attempt may have
been required to purge the lines and bring sufficient
fuel to the burner.
13.
If the first stage burner flame is not established
within ten seconds, close the manual fuel shutoff
valve(s), and open the master switch.
14.
If necessary, repeat steps 11 through 13 to establish
the first stage burner flame. Then proceed to step
15.
15.
When the first stage burner flame is established, the
sequence will advance to RUN. Make burner adjust-
ments for flame stability and input rating. If a sec-
ond stage is used, proceed to step 18.
16.
Shut down the system by opening the burner switch
or by lowering the set point of the operating control-
ler. Make sure the burner flame goes out and all
automatic fuel valve(s) close.
17.
If used, remove the bypass jumpers from the low fuel
pressure limit and subbase.
18.
If a second stage is used, make sure the automatic
second stage fuel valve(s) has opened. Check the
lightoff as follows (otherwise proceed to step 19):
a. Open the manual second stage fuel valve(s).
b. Restart the system by raising the set point of the
operating controller.
c. When the first stage burner flame is established,
watch for the automatic second stage fuel
valve(s) to open. Observe that the second stage
lights off properly.
d. Make burner adjustments for flame stability and
input rating.
e. Shut down the system by lowering the set point
of the operating controller. Make sure the burner
flame goes out and all automatic fuel valve(s)
close.
f.
Proceed to step 19.
19.
Restart the system by closing the burner switch
and/or raising the set point of the operating control-
ler. Observe that the burner flame is established
during PILOT IGN, within the normal lightoff time
specified by the equipment manufacturer.
20.
Measure the flame signal. Continue to check for the
proper signal, see Table , through the RUN period.
Check the signal at both high and low firing rate
positions and while modulating. Any pulsating or
unsteady readings will require further attention.
21.
Make sure all readings are in the required ranges
before proceeding.
