Honeywell 7800 Series Manual page 37

4. Let the sequence advance through PURGE. When
"PURGE HOLD: T21" is displayed on the Keyboard Dis-
play Module VFD, press the Start button and the RM7838B
will bring on the ignition and the pilot valve. When the pilot
ignites, the FLAME LED will energize and the Alarm will
shut off. Proceed to step 7.
5. If the pilot flame is not established within four or ten
seconds, safety shutdown will occur. Consult the equipment
operating manual for further information.
6. Push the reset pushbutton. When "PURGE HOLD:
T21" is displayed, press the Start button again. If the pilot
still does not light, make the following ignition/pilot
adjustments:
a. Open the master switch and remove the RM7838B
from the subbase.
b. On the subbase, jumper terminal 4 to ignition ter-
minal 10.
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
recommendation.
e. Make sure the ignition electrode(s) is clean.
f. Close the master switch and observe the spark.
g. After a strong continuous spark is obtained, open
the master switch and add another jumper on the
subbase from terminal 4 to pilot terminal 8.
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 lights properly and stays lit, open
the master switch and remove the jumper(s) from
terminal(s) 4 - 8 and 4 - 10 of the subbase.
k. Check for adequate bleeding of the fuel line.
l. Reinstall the RM7838B on the subbase.
m. Repeat steps 3 and 4.
7. With the pilot lit, measure the flame signal. If the pilot
flame signal is unsteady or approaching the 1.25 Vdc mini-
mum value, adjust the pilot flame size or detector sighting to
provide a maximum, steady flame signal.
8. Recycle the system through another startup to recheck
lightoff and pilot flame signal.
9. Initiate main ignition by opening the Pilot Valve Hold
Switch (if used), closing the Manual Valve Open Switch or
switching the Run/Test Switch to RUN position. When the
MAIN IGN period is displayed on the VFD, 120 Vac will be
on terminal 9. Make sure the automatic main fuel valve (if
used) is open; then smoothly open the manual main fuel
shutoff valve(s) and watch for main burner flame ignition. If
the main burner flame is not established within two seconds
or the normal lightoff time as specified by the equipment
manufacturer, close the manual main fuel shut-off valve(s).
When the main burner flame is established, proceed to step 13.
SERVICE NOTE: If configuration jumper 2 is clipped,
switch Run/Test Switch to TEST position.
10. Allow a few minutes for the combustion chamber to
purge. Smoothly open manual fuel shutoff valve(s) and try
lightoff again. (The first attempt may have been required to
purge the lines and bring sufficient fuel to the burner.)
11. If the main burner flame is not established within two
seconds or the normal lightoff time specified by the equip-
ment manufacturer, close manual main fuel shutoff valves(s).
Check all burner adjustments.
12. 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.
13. Repeat steps 10 through 13 to establish the main burner
flame; then proceed to step 14.
14. With the sequence in RUN, make burner adjustments
for flame stability and Btu input rating.
15. Shut down the system by opening the burner switch.
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
fuel valve(s) close.
16. Restart the system by closing the burner switch.
When purge is complete and "PURGE HOLD: T21" is dis-
played, press the Start button and observe that the pilot is
established during PILOT IGN and the main burner flame
is established during MAIN IGN within the normal lightoff
time.
17. Measure the flame signal. Continue to check for the
proper signal, see Table 8, through the RUN period. Check
the signal at both High and Low Firing Rate positions and
while modulating.
18. Run the burner through another sequence, observing
the flame signal for:
a. Pilot flame alone (unless using direct spark ignition).
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.
19. Make sure all readings are in the required ranges
before proceeding.
20. Press the Stop Button and note the proper valve clo-
sures The RM7838B will initiate a purge sequence and when
"PURGE HOLD: T21" is displayed, the purge is complete
the RM7838B is waitting for a Start command.
NOTE: After completing these tests, open the master switch
and remove all test jumpers from the subbase terminals,
limits/controls or switches.
21. Return the system to normal operation.
37
RM7838B
CHECKOUT
65-0120—1