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PILOT TURNDOWN TEST
CAUTION
The pilot turndown test should be performed only
by qualified personnel and the instructions should
be followed carefully.
On systems that prove a pilot before the main fuel valve
can be opened, perform a pilot turndown test to prove that the
main burner can be lighted by the smallest pilot that will hold
in the flame relay. Perform a flame current check before and
after the pilot turndown test.
1. Open the main power switch.
2. Shut off the fuel supply to the main burner only by
closing the manual main burner shutoff cock. Do not shut off
the fuel supply to the pilot valve.
3. Restore power to the relay.
4. Start the system by raising the setpoint of the control-
ler (or pressing the Start button). The pilot will light and pull
in the flame relay.
5. Reduce the size of the pilot flame to the turndown
condition by slowly closing the manual valve on the pilot gas
line. At the turndown condition, the pilot will be small
enough to just hold in the flame relay (2K).
a. Turn down the pilot until relay 2K drops out.
b. Slowly turn up the pilot again just until relay 2K pulls
back in.
c. Again turn down the pilot slightly, but not enough so
the relay drops out.
If the relay drops out again, simply turn up the pilot and
try again. The closer the pilot is to the dropout condition, the
more conclusive the test will be.
6. Check that the pilot is lit and relay 2K is pulled in.
7. Open the manual main burner shutoff cock. Main
flame should light smoothly within one second. If the burner
does not light within one second, close the shutoff cock and
shut off power to the relay. Proceed to step 9.
8. If the burner lights, repeat step 7 two or three times to
verify smooth lightoff.
9. If the lightoff is unsatisfactory, readjust the flame
detector to require a larger pilot flame to hold in the flame
relay. This usually requires:
a. Resighting an ultraviolet or photocell type detector
farther out on the axis of a pilot flame, or
b. Adjusting a flame rod detector so that a larger mini-
mum pilot is required.
CAUTION
If the pilot needs to be adjusted and rechecked,
allow five minutes for the purge of unburned gases
in the firebox before proceeding to the next step.
10. Repeat the entire turndown test until the flame is
established promptly in step 7.
11. Turn up the pilot to full flame at the completion of the
test. Perform a flame current check before leaving the job.
SAFE SHUTDOWN CHECKS
Limit Action
With the burner operating, lower the high limit setting to
simulate an overheated boiler or furnace. Normal shutdown
should occur. Restore the normal limit setting and the burner
should restart.
Use manual reset limits with the RA890F to prevent the
system from cycling off the high limit and to assure that the
condition that causes the limit action is detected as soon as
possible.
Flame Failure
With the burner operating, close the manual fuel valves to
simulate a flame failure. System should lock out in safety
switch timing (15 or 30 seconds). After the safety switch
cools, open the manual valves and reset the safety switch.
The burner should restart.
Power Failure
With the burner operating, open and then immediately
close the line switch to simulate a power failure. Burner
should shut down. After a short delay for component check,
burner should restart and operate normally.
HOT REFRACTORY HOLD-IN (PHOTOCELL OIL
INSTALLATION ONLY)
If hot refractory holds in the flame relay at the end of the
burner-on cycle, the system cannot restart until the relay
drops out. Check for hot refractory hold-in by observing the
flame relay for immediate dropout at the end of a long
burner-on period. If the relay does not drop out, resight the
photocell so it does not sight the refractory, or decrease
photocell sensitivity using aperture disks or filters.
NOTE: At the completion of all checkout tests, make sure
that the RA890 is not on safety lockout, that the pilot is
turned up to its normal level, and that all limit settings are
correct. Operate the system through one normal cycle
before leaving the installation.
9
RA890F
C H E C K O U T
60-2034—7
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