CHAPTERS
The
control adjustment may be made during the
prepurge period
of
operation by stopping the
programmer during the prepurge period through
the use
of
the
TEST
switch. Refer to the control
instruction bulletin for details..
·
The
adjustment screw
of
the atomizing air prov-
ing switch then can be adjusted until it breaks the
circuiL
At
this point, the programmer will lock-
out and it must be manually reset before it can
be
restarted.
Tum
the adjusting screw up a half
tum
or
so
to remake the circuiL
Since the adjustment
of
the air switch may be
made either during the damper closed
or
damper
open position
of
prepurge,
~t
is also possible to
make the adjustment with the relay stopped in the
damper open position in a similar manner to the
adjustment
of
the combustion air proving switch
described in the previous section.
After making the adjustment, recycle the control
to be sure that normal operation is obtained.
The
TEST
switch must be set
to
the RUN. position.
0.
GAS
PILOT
FLAME
ADJUSTMENT
The size
of
the gas pilot flame
is
regulated by
adjusting the gas flow through the pilot gas
regulator and the adjusting cock.
The
flame must
be
sufficient to ignite the main flame and to be
seen by the flame detector but an extremely large
flame
is not required
..
An
overly rich flame can
cause sooting
of
the flame detector. Too small a
flame can cause ignition problems.
Although it is possible to visibly adjust the size
of
the pilot flame, it is preferable
to
obtain a
microamp reading
of
the flame signal.
The
amplifier
of
the standardly
used
program
relay has a meter jack for this purpose. This
reading may be measured with a good quality
micro-ammeter
or
a suitable multi-meter with a
0 to 25 micro-amp
DC
rating.
CHAPTER 5-10
ADJUSTMENT PROCEDURES
The
meter is connected
to
the
jack
using a meter
connecting plug harness (Cleaver-Brooks 884-
72). Connect the plus (red meter lead) to the red
tab
of
the harness and the minus (black meter
lead)
to
the black tab before inserting the plug in "
the meter jack.
The
program relay used may
be
of
the type that
provides message information that includes a
constant flame signal
of
DC
voltage. In this case
a separate
DC
voltmeter is not required.
To
Measure and Adjust Pilot:
(1) When making a pilot adjustment, tum
the
manual-automatic
switch
to
"manual" and the manual flame control
to
"close." Open both the pilot shutoff
cock and the pilot adjusting cock. The
main gas cock should remain closed.
The
regulator
in
the
pilot
line,
if
provided, reduces the gas pressure to suit
the pilot requirement
of
between 5-10"
W.C.
The
final adjustment
of
the pilot
flame with the adjusting cock is less
sen-
sitive with a lower pilot pressure.
(2) Connect the micro-ammeter as
out-
lined earlier.
(3)
Tum
the burner switch on.
Let
the
burner go through the normal prepurge
cycle. When the ignition trial period is
signaled, set the test switch
to
the
TEST
position
to
stop the sequence.
(4)
If
the pilot flame
is
not established
within ten seconds, tum
off
the burner
switch. Repeat the lighting attempt.
750-150
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