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9−Electronic Ignitor (A73)
The electronic ignitor provides the needed hot spark at the
electrodes to ignite the fuel mixture. The ignitor is a solid
state transformer . O23, OHR23 and OF23−1 through −4
units have 115V primary and 14,000V secondary wind
ings. O23, OHR23 and OF23−5 units have 120V primary
and 20,000V secondary windings. The center of the sec
ondary winding is grounded. Each secondary terminal is
7000V to ground and the total voltage between the elec
trodes is 14,000V.
NOTE−The leads for the solid state transformer are re
placeable and are available in a kit form.
NOTE−When testing the solid state transformer, do not
use a transformer tester designed for iron magnet trans
formers. Damage to the tester may result.
Testing the Ignitor
WARNING
SHOCK HAZARD
Do not touch ignitor or any metal touching ignitor
when ignitor is energized. Can result in serious per
sonal injury.
If the ignitor fails it will not produce a spark. Looking and
listening for the arc is a simple way to check. The most sure
way is to perform the screwdriver check. By placing the
blade of an insulated screwdrivere across the ignitor termi
nal leads will test for an arc. First,
r
emove power from the
burner and disconnect the oil supply from nozzle. The cad
cell will not let the control energize the ignitor if the cad cell
senses light.
Therefore remove one lead of the cad cell
from the burner control, or remove the cad cell all together
(do not forget to put back when test is complete). Place the
screwdriver blade across the terminals and slowly raise
one end of the blade off the terminal while the other re
mains in contact with the other terminal. There should be
an arc from terminal to the blade up to 3/4" away. If not re
place the ignitor. If an arc is present then place one end of
the screwdriver on one terminal and the other end with the
grounded baseplate. Raise the blade from the baseplate
and draw an arc. Repeat with the other terminal. If the arc
from the baseplate to one terminal is weaker than the arc
from the baseplate to the other terminal, replace the ignitor.
10−Gun Assembly
The gun assembly receives oil from the oil pump and feeds
it to the nozzle. The nozzle converts liquid oil into a fog−like
mist that is discharged through the flame retention head
into the combustion chamber.
11−Flame Retention Heads
The stainless steel flame retention head (see figure 11)
is used to swirl (cone) the foglike oil and air mixture as it
enters the combustion chamber. Three different heads
are used in the O23/OHR23/OF23. The firing rate dic
tates which head is used. See table 4. The greater the
FB number the larger the slots on the head. When com
bustion takes place, the flame will be cylindrical com
pact shaped as a result.
FLAME RETENTION HEAD
FB3 SHOWN
FIGURE 11
C−Primary Limit Control (S10)
The primary limit on all O23, OHR23, and OF23 units, is
located on the vestibule panel (see figures 1 through 3 for
location and figure 12 for type). When excess heat is
sensed in the heat exchanger, the limit will open. If the limit
is tripped, the blower control deenergizes the thermostat,
in turn shutting down the unit. The limit automatically re
sets when unit temperature returns to normal. The switch is
factory set and cannot be adjusted. The switch has a different
setpoint for each unit model number (see table 7). The set
point is printed on the face plate of the limit.
