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3. Avoid installation considerations that can influence
detector operation and maximum lead wire length, such
as:
a. Moisture.
b. Ignition interference.
c. High resistance connections—poor grounds.
d. Lead wire capacitance.
e. Voltage fluctuations.
f.
Induced line transients.
g. Floating grounds—ground at some voltage above
earth ground.
h. No G wire—burner used as ground.
i.
Detector output less than maximum attainable for the
installation (inadequate sighting.
IMPORTANT:
Do not run the flame detector wiring in the same con-
duit with high voltage ignition transformer wires.
Connecting Detectors In Parallel
(C7927 Can Not be Used in Parallel)
For a flame that is difficult to sight, using two flame detectors
connected in parallel will reduce the occurrence of nuisance
shutdowns. If only one of the parallel detectors loses the flame
signal, the other will continue to indicate the presence
of the flame and keep the burner in operation.
When the flame detectors are connected in parallel, the low
level background signals are additive. Therefore, no more than
two C7027A, C7035A, or C7044A Flame Detectors should be
paralleled. Furthermore, the background signal increases as
temperature decreases. Because of this, the minimum ambient
operating temperature must be increased when the C7027A,
C7035A or C7044A Flame Detectors are paralleled. (C7927
can not be used in parallel.)
When using detectors rated for a minimum of 0°F (-18°C), limit
the minimum ambient temperature at the detectors to 32°F
(0°C). When using detectors rated for a minimum of
-40°F (-40°C), limit the minimum ambient temperature at the
detectors to -10°F (-23°C).
Connect the blue lead wires of both detectors to the F terminal
of the wiring subbase or terminal strip, and the white lead wires
of both detectors to the G terminal, as shown in Fig. 9.
Earth Ground
The detector and the flame safeguard control must be
connected to earth ground. A convenient method of
accomplishing this is to connect the detector to the flame
safeguard control with a flexible conduit, or ensure a good
ground connection at the mounting bracket.
BLUE
UV DETECTOR
WHITE
BLUE
UV DETECTOR
WHITE
OPTIONAL
SECOND
DETECTOR
Fig. 9. Wiring C7027A, C7035A, and
C7044A flame detectors in parallel.
WIRING SUBBASE
OR
TERMINAL STRIP
F
G
M3018A
9
®
MINIPEEPER
ULTRAVIOLET FLAME DETECTORS
ADJUSTMENTS AND
CHECKOUT
Before welding the C7027A, C7927A or C7035A sight pipe
in its final location, or before tightening the C7044A clamp
screw, complete both the adjustments and checkout tests that
follow and any required by the burner manufacturer.
UV Sensor Tube Test
NOTE: For initial burner light off, consult the burner manufac-
turer instructions or the instructions
for the flame safeguard control.
During the initial burner light off, make sure the flame
safeguard control starts (i.e., the load relay, usually 1K, pulls
in). If it does not start, visually check the sensing tube in the
C7027A, C7035A, or C7044A flame detector. If the tube
continues to glow when no flame is present, replace the
sensing tube (C7035A), or replace the detector (C7027A or
C7044A).
Adjust Detector Sighting Position
With the flame detector installed and burners running, adjust
the position of the flame detector for optimum flame signal. The
flame signal will be read in microamps or voltage (Vdc)
depending on the Honeywell flame safeguard combustion
control used.
Most existing Honeywell flame safeguard controls incorporate
a flame current jack on the flame amplifier or on the control
itself. The flame signal can be measured with a volt-ohmmeter
such as the Honeywell W136A. To measure the flame current
(signal), use a cable connector (part number 196146, included
with the W136A) in conjunction with the meter. With the
W136A (or equivalent) positioned at the zero to 25
microampere scale, make connections from the meter probes
to the two ends of the cable connector plug (red to red, black to
black). Make these connections before inserting the plug end
of the connector plug into the flame jack of the control
or control amplifier (see Fig. 10). Read the flame signal in
microamperes directly from the W136A meter. Refer to
Table 1 for the minimum acceptable flame currents.
W136A VOLT-
W136A SELECTOR
OHMMETER
SWITCH
RED (+)
METER
LEAD
BLACK (-) METER LEAD
Fig. 10. Measuring microamp flame signal.
196146 METER
CONNECTOR
PLUG
PLUG
FLAME SIGNAL
METER JACK
PLUG-IN FLAME
SIGNAL AMPLIFIER
RED CONNECTOR
BLACK CONNECTOR
M6532B
60-2026-16
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