Honeywell 7800 Series Installation Instructions Manual page 35

l. Reinstall the RM7888A on the subbase and close
the master switch, then return to step 3.
8. 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 sighting to provide a maximum and
steady flame signal.
9. Recycle the system to recheck lightoff and pilot
flame signal.
10. Energize Special Functions 2 (terminal 17) and 3
(terminal 19).
11. 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 18.
12. 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).
13. Recycle the system to recheck the lightoff and pilot
flame signal.
14. Smoothly open the manual fuel shutoff valve(s) and
try lightoff again. (The first re attempt may be
required to purge the lines and bring sufficient fuel
to the burner.)
15. If the main burner flame is not established within
five seconds or the normal lightoff time specified by
the equipment manufacturer, close the manual main
fuel shutoff valves(s). Check all burner adjustments.
16. 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.
17. Repeat steps 12 through 16 to establish the main
burner flame; then proceed to step 18.
18. With the sequence in RUN, make burner adjust-
ments for flame stability and Btu input rating.
19. Shut down the system by opening the burner switch
or by de-energizing terminal 6. 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.
20. Restart the system by closing the burner switch and/
or energizing terminal 6. Make sure that the pilot is
established during PILOT IGN. Energize terminals
17 and 19 and make sure that the main burner flame
is established during MAIN IGN within the normal
lightoff time.
21. Measure the flame signal. Continue to check for the
proper signal, see Table 11 through the RUN period.
Check the signal at both High and Low Firing Rate
positions and while modulating.
22. Run the burner through another sequence, observ-
ing the flame signal for:
a. Pilot flame alone (unless using DSI)
b. Pilot and main flame together.
c. Main flame alone. Also observe the time it takes
to light the main flame. Ignition of main flame
should be smooth.
RM7888A 7800 SERIES RELAY MODULE
23. Make sure all readings are in the required ranges
before proceeding.
24. 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 that do not use 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. Verify that the combustion chamber has been prop-
erly purged.
5. Close the master switch and start the system by
energizing terminal 6 (Special Function 1). See
RM7888A Sequence of Operation. The program
should start the ten second INITIATE sequence.
6. Ignition spark should occur. Listen for the click of
the first stage fuel solenoid valve(s).
7. Let the program sequence complete its cycle.
8. Open the manual fuel shutoff valve(s).
9. Push the reset pushbutton and recycle the program.
10. Watch for the FLAME LED to help determine when
the first stage burner flame is established. If it is
established, proceed to step 16.
11. If the first stage burner flame is not established
within four seconds, or within the normal lightoff
time specified by the equipment manufacturer, close
the manual fuel shutoff valve(s), and open the mas-
ter switch.
12. Check all burner adjustments.
13. 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.
14. If the first stage burner flame is not established
within four seconds, or within the normal lightoff
time specified by the equipment manufacturer, close
the manual fuel shutoff valve(s) and open the mas-
ter switch.
15. If necessary, repeat steps 12 through 14 to establish
the first stage burner flame after verifying that the
system has been properly purged. Then proceed to
step 16.
16. When the first stage burner flame is established, the
sequence will advance when the appropriate special
function input (terminal 17, 19, or 20) is energized.
See RM7888A Sequence of Operation. Make burner
adjustments for flame stability and input rating.
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