1-30 750-166
CB780/CB784
CHECKOUT
18. Restart the system by closing the burner switch and/or
raising the set point of the operating controller. 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 9, 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, observing
the flame signal for:
a. Pilot flame alone (DSI).
b. Pilot and main flame together.
c. Main flame alone (unless monitoring an intermit-
tent 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 subbase 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 equip-
ment 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.18 for CB780/CB784 sequencing. The program
sequence should start the ten second INITIATE sequence.
5. Let the sequence advance through PREPURGE. Igni-
tion 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 se-
quence through PREPURGE.
9. When PILOT IGN status is displayed , watch that the
first stage burner flame is established. If it is established,
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 POSTPURGE 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 adjustments
for flame stability and input rating. If a second 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 controller. 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 sec-
ond 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 controller. 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 9, 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.
NOTE: Upon completing these tests, open the master
switch and remove all test jumpers from the subbase
terminals, limits/controls or switches.
22. Return the system to normal operation.
PILOT TURNDOWN TEST (ALL INSTALLATIONS
USING A PILOT)
Perform this check on all installations that use a pilot. The
purpose of this test is to verify that the main burner can be lit
by the smallest pilot flame that will hold in the flame
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