15
66-2001—2
NOTE: The next step requires two people—one to open the
manual main fuel valve(s) and one to watch for ignition.
d. With the sequence in the normal burner run mode,
make sure that the automatic main fuel valve(s)
are open. Smoothly open the manual main fuel
shutoff valve and watch for main burner lightoff.
If the main flame is not established within five
seconds or the normal lightoff period specified by
the burner manufacturer, close the manual main
fuel shutoff valve and open the master switch.
Then proceed to step 8. If the burner flame is
established in the normal lightoff period, proceed
to step 14.
7. INTERRUPTED PILOT MODELS—When the se-
quence enters the pilot flame ignition trial period, set the
RUN/TEST switch to the TEST position to stop the se-
quence. The Flame Indicator LED will come on when the
pilot ignites. Very slowly turn down the pilot gas pressure,
reading the manometer or gauge as the pressure drops.
Stop immediately when the Flame Indicator LED goes
out. Note the pilot gas pressure at this point.
a. Immediately increase the pilot gas pressure until
the Flame Indicator LED comes back on. Slowly
decrease the pilot gas pressure to just above the
pressure noted in step 7 above.
b. Set the RUN/TEST switch to the RUN position
and allow the sequence to go on.
NOTE: The next step requires two people—one to open
the manual main fuel shutoff valve and one to watch
for ignition.
c. When the sequence enters the trial for main
flame period, make sure that the automatic main
fuel valve(s) is (are) open. Smoothly open the
manual main fuel shutoff valve and watch for
main flame ignition.
If the main flame is not established within five
seconds or the normal lightoff period specified by
the burner manufacturer, close the manual main
fuel shutoff valve, open the master switch and
proceed to step 8.
If the main burner flame is established in the
normal lightoff period, proceed to step 14.
8. Purge the combustion chamber to remove any un-
burned fuel; check all burner adjustments.
9. Wait about three minutes. Close the master switch
and allow the sequence to go through the prepurge. Repeat
step 6 or 7.
10. If the second attempt is unsuccessful, adjust the
flame detector so that a larger pilot flame is necessary to
make the Flame Indicator LED come on. This may require
repositioning the flame detector to sense farther out on the
pilot flame or adding an orifice plate.
11. Measure the pilot flame signal after adjusting the
flame detector to make sure that it is stable and is within the
limits set in Table 3.
12. Repeat steps 5 through 12 until the main burner
positively lights with the pilot just causing the Flame
Indicator LED to remain on.
13. Repeat the main burner lightoff several times with
the pilot at turndown.
14. When the main burner lights reliably with the pilot at
turndown, disconnect the manometer or gauge and turn up
the pilot to normal.
15. If used, remove the bypass jumpers from the low fuel
pressure limits.
16. Run the system through another cycle to check for
normal operation.
IGNITION INTERFERENCE TEST
(All Flame Rods)
Test to make certain that a false signal from a spark
ignition system is not superimposed on the flame signal.
Ignition interference can decrease or increase the
actual flame signal. If it decreases the signal enough, it
could cause safety shutdown. If the signal is increased
enough, it could cause Flame Indicator LED to come on
when the true flame signal is below the minimum accept-
able value.
TEST
Start the burner and measure the flame signal with both
the ignition and pilot (or main burner) on, and then with
only the pilot (or main burner) on. Any difference greater
than one-half microamp indicates ignition interference.
TO ELIMINATE IGNITION INTERFERENCE
1. Make sure there is enough ground area.
2. Be sure that the ignition electrode and the flame rod
are on opposite sides of the ground area.
3. Check for correct spacing on the ignition electrode:
a. 6,000 volt systems: 1/16 to 3/32 in. [1.6 to 2.4 mm].
b. 10,000 volt systems: 1/8 in. [3.2 mm].
4. Make sure the leadwires from the flame rod and
ignition electrode are not too close together.
5. Replace any deteriorated leadwires.
6. If the problem cannot be eliminated, consider chang-
ing to an ultraviolet flame detection system.
HOT REFRACTORY HOLD-IN TEST (Rectifying
Photocells)
Test to make certain that hot refractory will not cause the
Flame Indicator LED to remain on after the burner goes
out. This condition would delay response to flame failure
and also prevent a system restart as long as the hot refrac-
tory is detected.
First check the R7795 Flame Signal Amplifier by start-
ing the burner cycle. As soon as the sequence stops in the
run period, lower the burner controller setpoint to shut
down the system while the refractory is cool. Measure the
time necessary for the Flame Indicator LED to go out after
the flame extinguishes. If it takes more than four seconds,
open the master switch and replace the R7795.
To check rectifying photocells for hot refractory hold-
ing, operate the burner until the refractory reaches its
maximum operating temperature. Then lower the setpoint
of the burner controller to terminate the firing cycle, or set
the Fuel Selector switch to OFF. DO NOT OPEN THE
MASTER SWITCH. Observe the flame go out.
R7795A,B,C,D
CHECKOUT