Honeywell 7800 Series Product Data page 26

7800 SERIES RM7896A,B,C,D RELAY MODULE
close all manual fuel shutoff valves or open the electrical
circuits of all automatic fuel valves. Visually observe when
the burner flame or FLAME LED goes out. If this takes more
than three seconds, the infrared detector is sensing hot
refractory. Immediately terminate the firing cycle. Lower the
set point to the operating controller, or set the Fuel Selector
Switch to OFF. Do not open the master switch.
NOTE: Some burners continue to purge oil lines between
the valve(s) and nozzle(s) even though the fuel
valve(s) is closed. Terminating the firing cycle
(instead of opening the master switch) will allow
purging of the combustion chamber. This will reduce
a buildup of fuel vapors in the combustion chamber
caused by oil line purging.
If the detector is sensing hot refractory, the condition must be
corrected. Add an orifice plate in front of the cell to restrict the
viewing area of the detector. If this does not correct the
problem, resight the detector at a cooler, more distant part of
the combustion chamber. While resighting the detector, be
aware that it must also properly sight the flame. When using
an infrared detector, try lengthening the sight pipe or
decreasing the pipe size (diameter). For details, refer to the
detector Instructions and the equipment Operating Manual.
Continue adjustments until hot refractory hold-in is eliminated.
Ultraviolet Sensor, Ignition Spark Response
Test (All Ultraviolet Detectors)
Test to be sure that the ignition spark is not actuating the
FLAME LED:
1. Close the pilot and main burner manual fuel shutoff
valve(s).
2. Start the burner and run through the PILOT IGN period.
Ignition spark should occur, but the flame signal should
not be more than 0.5 Vdc and the FLAME LED should
not turn on.
3. If the flame signal is higher than 0.5 Vdc and the
FLAME LED does come on, consult the equipment
Operating Manual and resight the detector farther out
from the spark, or away from possible reflection. It may
be necessary to construct a barrier to block the ignition
spark from the detector view. Continue adjustments
until the flame signal due to ignition spark is less than
0.5 Vdc.
NOTE: The Honeywell Q624A Solid State Spark Generator
will prevent detection of ignition spark when properly
applied with the C7027, C7035 or C7044 Minipeeper
Ultraviolet Flame Detectors. The Q624A is only for
use with gas pilots.
Response to Other Ultraviolet Sources
Under certain conditions, an ultraviolet detector will respond
to other ultraviolet sources as if it is sensing a flame. These
ultraviolet sources include artificial light, such as
incandescent or fluorescent bulbs, mercury and sodium vapor
lamps or daylight. To check for proper detector operation,
check the Flame Failure Response Time (FFRT) and conduct
Safety Shutdown tests under all operating conditions.
65-0193
Flame Signal with Hot Combustion Chamber
(All Installations)
After all initial start-up tests and burner adjustments are
completed, operate the burner until the combustion chamber
is at the maximum expected temperature. Observe the
equipment manufacturer warmup instructions. Recycle the
burner under these hot conditions and measure the flame
signal. Check the pilot alone, the main burner flame alone,
and both together (unless monitoring only the pilot flame
when using an intermittent pilot, or only the main burner flame
when using DSI).
Check the FFRT of the Flame Amplifier. Lower the set point of
the operating controller and observe the time it takes for the
burner flame to go out. This should be within .8 or 3 seconds
maximum depending on the amplifier selected.
If the flame signal is too low or unsteady, check the flame
detector temperature. Relocate the detector if the
temperature is too high. If necessary, realign the sighting to
obtain the proper signal and response time. If the response
time is still too slow, replace the Plug-in Flame Signal
Amplifier. If the detector is relocated or resighted, or the
amplifier is replaced, repeat all required Checkout tests.
Safety Shutdown Tests
(All Installations)
Perform these tests at the end of Checkout after all other tests
have been completed. If used, the external alarm should turn
on. Press the RM7896 reset pushbutton to restart the system.
1. Close the Airflow interlock during STANDBY for 120 sec-
onds (RM7896B,D).
2. Close the Airflow Interlock during PREPURGE, PILOT
IGN, MAIN IGN or RUN period.
a. Safety shutdown will occur if the Airflow ILK Switch
Failure configuration jumper (JR3) is clipped.
3. Detect flame 40 seconds after entry to STANDBY. Detect
flame 30 seconds during measured PREPURGE time.
a. Simulate a flame to cause the flame signal voltage
level to be at least 1.25 Vdc for 40 seconds after
entry to STANDBY and also simulate a flame signal
for 30 seconds during PREPURGE.
b. Safety shutdown will occur.
4. Failure to ignite pilot.
a. Close the pilot and main fuel manual shutoff valve(s).
b. Depress the reset pushbutton.
c. Start the system.
d. Automatic pilot valve(s) should be energized but the
pilot cannot ignite.
e. Safety shutdown will occur.
5. Failure to ignite main.
a. Open the manual pilot valve(s); leave the main fuel
manual shutoff valve(s) closed.
b. Depress the reset push button.
c. Start the system.
d. Pilot should ignite and the flame signal should be at
least 1.25 Vdc but the main burner cannot light.
e. Close the manual pilot valve(s).
f. Flame signal should drop below 1.25 Vdc within .8 or
3 seconds (depending on the FFRT of the amplifier)
after the pilot goes out.
g. Safety shutdown will occur.
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