Honeywell 7800 Series Manual page 24

RM7895A,B,C,D
CHECKOUT
INITIAL LIGHTOFF CHECK FOR PROVED PILOT
Perform this check on all installations that use a pilot.
It should immediately follow the preliminary inspection.
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. 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), very slightly open the manual main valve to
supply pilot gas flow. Make sure the main fuel is shutoff
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 Figs. 15, 16 or 18. The primary sequence
should start the ten-second INITIATE sequence.
4. Let the sequence advance through PREPURGE.
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, safety shutdown occurs. Let the sequence com-
plete 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 RM7895
from the subbase.
b. On the subbase, jumper terminal 5 to ignition
terminals 8 or 10; refer to the appropriate wiring
diagram to determine the proper terminal. Dis-
connect the leadwire to the pilot valve if it is
connected to the same terminal.
c. Close the master switch to energize only the
ignition 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 5 (L1) to the pilot terminal 8.
Reconnect the leadwire from the pilot valve if it
was disconnected in step b.
h. Close the master switch to energize both the
ignition 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 5 - 8 or 5 - 10 of the subbase.
k. Check for adequate bleeding of the fuel line.
l. Reinstall the RM7895 on the subbase and close
the master switch, then return to step 4.
7. When 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 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 16.
10. 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
shut-off 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 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
equipment manufacturer, close the manual main fuel
shut-off 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 8 through 14 to establish the main
burner flame; then proceed to step 16.
16. With the sequence in RUN, make burner adjust-
ments 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 MAIN
IGN 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, observ-
ing 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 inter-
mittent pilot).
Also observe the time it takes to light the main flame.
Ignition of main flame should be smooth.
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