Honeywell 7800 Series Manual page 27

program sequence should start the ten second INITIATE
sequence.
4. Let the sequence advance through PREPURGE. Igni-
tion spark should occur and the pilot should light. If the pilot
ignites, the FLAME LED will be energized. Proceed to
step 7.
5. If the pilot flame is not established in four or ten
seconds, safety shutdown occurs. Let the sequence complete
its cycle. Consult the equipment operating manual for further
information.
6. Push the reset pushbutton, and let the system recycle
once. If the pilot still does not ignite, make the following
ignition/pilot adjustments:
a. Open the master switch and remove the RM7840
from the subbase.
b. On the subbase, jumper terminal 4 to ignition
terminals 8, 10 or 21; refer to the appropriate wiring
diagram to determine the proper terminal. Discon-
nect the leadwire to the pilot valve if it is connected
to the same terminal.
c. Close the master switch to energize only the igni-
tion transformer.
d. If the ignition spark is not strong and continuous,
open the master switch and adjust the ignition
electrode spark gap setting to the manufacturer
recommendations.
e. Make sure the ignition electrodes are clean.
f. Close the master switch and observe the spark.
g. After a continuous spark is obtained, open the
master switch and add a jumper on the subbase from
terminal 4 (L1) to the pilot terminal 8 or 21. Recon-
nect the leadwire from the pilot valve if it was
disconnected in step b.
h. Close the master switch to energize both the igni-
tion transformer and the pilot valve.
i. If the pilot does not ignite and if the ignition spark
is still continuous, adjust the pressure regulator
until a pilot is established.
j. When the pilot ignites properly and stays ignited,
open the master switch and remove the jumpers
from terminals 4 - 8, 4 - 10 and 4 - 21 of the subbase.
k. Check for adequate bleeding of the fuel line.
l. Reinstall the RM7840 on the subbase and close the
7. When the pilot ignites, measure the flame signal. If the
pilot flame signal is unsteady or approaching the 1.25 Vdc
minimum value, adjust the pilot flame size or detector sight-
ing to provide a maximum and steady flame signal.
8. Recycle the system to recheck lightoff and pilot flame
signal.
9. When the MAIN IGN period is displayed by the MAIN
LED, make sure the automatic main fuel valve is open; then
smoothly open the manual main fuel shutoff valve(s) and
watch for main burner flame ignition. When the main burner
flame is established, proceed to step 15.
10. If the main burner flame is not established within five
seconds or the normal lightoff time as specified by the
equipment manufacturer, close the manual main fuel shutoff
valve(s).
11. Recycle the system to recheck the lightoff and pilot
flame signal.
12. Smoothly open the manual fuel shutoff valve(s) and try
lightoff again. (The first reattempt may be required to purge
the lines and bring sufficient fuel to the burner.)
13. If the main burner flame is not established within five
seconds or the normal lightoff time specified by the equip-
ment manufacturer, close the manual main fuel shutoff
valves(s). Check all burner adjustments.
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 adjustments
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 controller. 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 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 6, 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 (unless using 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 that do not use a
pilot. It should immediately follow the preliminary inspec-
tion. Refer to the appropriate sample block diagram of field
wiring for the ignition transformer and fuel valve(s) hookup.
27
RM7840E,G,L,M
CHECKOUT
65-0087—2