7800 SERIES EC7885A/RM7885A RELAY MODULE
65-0203
27
To check rectifying photocells for hot refractory hold-in,
operate the burner until the refractory reaches its maximum
temperature. Then terminate the firing cycle by pressing the
Stop Switch. Do not open the master switch. Visually observe
when the burner flame or FLAME LED goes out. If this takes
longer than .8 or 3 seconds (depending on the FFRT of the
amplifier), the photocell is sensing hot refractory. This
condition must be corrected as described in the last
paragraph of this test.
Infrared (lead sulfide) detectors can respond to infrared rays
emitted by a hot refractory, even when the refractory has
visibly ceased to glow. Infrared radiation from a hot refractory
is steady, but radiation from a flame has a flickering
characteristic. The infrared detection system responds only to
flickering infrared radiation; it can reject a steady signal from
hot refractory. The refractory steady signal can be made to
fluctuate if it is reflected, bent or blocked by smoke or fuel
mist within the combustion chamber. Be careful when
applying an infrared system to verify its response to flame
only.
To check infrared (lead sulfide) detectors for hot refractory
hold-in, operate the burner until the refractory reaches its
maximum temperature. If the installation has a multi-fuel
burner, burn the heaviest fuel that is most likely to reflect,
bend or obscure the hot refractory steady infrared radiation.
When the maximum refractory temperature is reached, press
the Stop Switch. If the FLAME LED takes longer than three
seconds after the flame goes out, the infrared detector is
sensing hot refractory. Do not open the master switch.
NOTE:
Some burners continue to purge their 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) allows
purging of the combustion chamber. This reduces 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, you can also 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. Press the Start Switch. Ignition spark only will 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.
4. Open the pilot and main burner manual fuel shutoff
valve(s).
NOTE:
The Honeywell Q624A Solid State Spark Generator
prevents detection of ignition spark when properly
applied with the C7027, C7035 or C7044 Minipeeper
Ultraviolet Flame Detector. The Q624A is only for
use with gas pilots.
Response to Other Ultraviolet Sources
Under certain conditions, an ultraviolet detector responds 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.
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 warm-up instructions. Recycle the
burner under these hot conditions and measure the flame
signal. Check the pilot alone for non-DSI applications or the
main burner flame for DSI applications.
Also check the FFRT. Press the Stop Switch 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 are complete.
1. Detect flame 40 seconds after entry to STANDBY for a
total time period of 30 seconds.
a.
Simulate a flame to cause the flame signal
voltage level to be at least 1.25 Vdc for 30
seconds after entry to STANDBY.
b.
Press the Start Switch. No spark or pilot valve
should be energized.
