Form I-RA/D 140/235 (Version A), Mfg No. 110318 Rev 4, Page 35
Compressed air for atomizing the used oil is supplied by a piston-type
compressor mounted on the service tray. Model RA/RAD 140 and
235 heaters require air pressure within a 9 to 12 psi range for proper
oil atomization. To assure that the correct atomizing air pressure is
available, a pressure switch permits oil flow to the nozzle only when
a minimum of 9 psi is sensed.
Combustion air is supplied by a blower contained in the burner hous-
ing. An adjustable air shutter and air band located on the outside of the
burner housing control the quantity of combustion air. Both are preset
at the factory and should be changed only if the CO
2
measurement
indicates the need to do so. See Check-Test-Start, for instructions
for measuring CO
2
.
Ignition of the atomized oil and combustion air mixture is accom-
plished by a high voltage spark across the two electrodes located
near the atomizing nozzle. Ignition of the oil is detected by a cadmium
sulfide flame sensor. Light produced by the flame lowers the electri
-
cal resistance of the cad cell. This change is sensed by the ignition
controller which allows a continued flow of oil and shuts off the spark
transformer after a 30-second trial-for- ignition period.
If for some reason, ignition does not occur or the flame goes out during
the trial period, the primary control will lockout. To restart, the safety
switch must be manually reset by pushing the red reset button on the
ignition control. Depress and hold the reset button for three seconds.
If the heater does not ignite, contact your service person.
If the instructions in this manual are followed, excessive amounts of
unburned oil will not accumulate inside the combustion chamber. If
the caution statement about resetting the controller more than one
time is not heeded, then unburned oil will accumulate in the combus-
tion chamber.
If unburned oil accumulates, DO NOT
attempt to
fire the heater and burn off the oil. Remove the combustion chamber
access panels as described in Maintenance Section, “Inspecting
and Removing Soot and Ash from the Combustion Chamber/Heat
Exchanger”. Wipe out any accumulated oil with cloth rags. Properly
dispose of the rags.
If the flame fails during normal operation, the heater will go into lockout
requiring manual reset of the primary controller. Depress and hold the
reset button for three seconds. If the heater does not ignite, contact
your service person.
If power fails, the heater will shut down and normal trial for ignition
will begin on call for heat when the power is restored.
Approximately 1-1/2 to 2 minutes after the thermostat calls for heat
and ignition is established, the circulating fans or blowers will come
on. The circulating airflow will continue about three minutes after the
burner shuts down.
General
Operation
Continued
CAUTION: Do not
reset the primary
control more than
one time. If the
heater does not
ignite, contact your
service person.
