Honeywell 7800 SERIES Manual page 21

1. Open the master switch.
2. Make sure that the manual main fuel shutoff valve(s)
is closed. Open the manual pilot shutoff valve. If the pilot
takeoff is downstream from the manual main fuel shutoff
valve(s), slightly open the manual main valve to supply pilot
gas flow. Make sure the main fuel is shut off just upstream
from the burner inlet, or disconnect power from the automatic
main fuel valve(s).
3. Close the master switch and start the system with a call
for heat by raising the set point of the operating controller, see
Fig. 13 or RM7890 sequence. The primary sequence should
start the SAFE-START CHECK sequence (except
RM7890C).
4. Let the sequence advance through STANDBY and
SAFE-START CHECK. Ignition 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 (30 seconds for RM7890A1031), 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 RM7890
from the subbase.
b. On the subbase, jumper terminal 3 to ignition
terminals 8 or 10; 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 3 (L1) to the pilot terminal 8. Reconnect
the leadwire from the pilot valve if it was discon-
nected 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 jumper(s)
from terminals 3 - 8 or 3 - 10 of the subbase.
k. Check for adequate bleeding of the fuel line.
l. Reinstall the RM7890 on the subbase and close the
master switch and return to step 4.
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
sighting to provide a maximum and steady flame signal.
8. Recycle the system to recheck lightoff and pilot flame
signal.
9. When the RUN 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 16.
10. 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
valve(s).
11. Recycle the system to recheck lightoff and pilot flame
signal.
12. Let the RM7890 recycle to the RUN period. Smoothly
open the 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.)
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.
c. Check for adequate 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 the 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 RUN within the normal
lightoff time.
19. Measure the flame signal. Continue to check for the
proper signal, see Table 5, through the RUN period.
20. Run the burner through another sequence, observing
the flame signal for:
a. Pilot flame alone (unless using direct spark igni-
tion).
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. Return the system to normal operation.
22. 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.
21
RM7890A,B,C
CHECKOUT
65-0126—2