Form 465, Page 34
external to the burner preheats the oil to approximately 175
o
F. A pair of 30
watt heating elements on the fuel line and nozzle assembly within the burner
maintain an oil atomizing temperature of 160
o
F. Temperature sensors pre-
vent burner operation until the proper temperatures are attained. Oil tem-
perature is maintained continuously as long as the electrical power is on to
the heater.
Compressed air for atomizing the used oil is supplied by a piston-type com-
pressor mounted on the side of the boiler. Models RAB 140 and 235 require
air pressure within a 9 to 12 psi range for proper oil atomization. Model
RAB 350 requires air pressure in a range of 12 to 15 psi. Model RAB 500
requires 12 to 16 psi. To assure that the correct atomizing air pressure is
available, a pressure switch permits oil flow to the nozzle only when the
minimum psi required for that size of burner is sensed.
Combustion air is supplied by a blower contained in the burner housing. An
adjustable air shutter and air band located on the outside of the burner hous-
ing 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
. (NOTE: These
settings will require adjustment for high altitude operation.)
Ignition of the atomized oil and combustion air mixture is accomplished 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 electrical 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 control. De-
press and hold for four seconds.
If the instructions in this manual are followed, excessive amounts of un-
burned oil will not accumulate inside the combustion chamber. If the cau-
tion statement about resetting the controller more than one time is not heeded,
then unburned oil will accumulate in the combustion chamber.
If unburned
oil accumulates, DO NOT
attempt to fire the boiler and burn off the oil.
Remove the combustion chamber access panels as described in Mainte-
nance Section, “Inspecting and Removing Soot and Ash”. Wipe out any
accumulated oil with cloth rags. Properly dispose of the rags.
If the flame fails during normal operation, the burner will go into a 90-
second “recycle” mode (allow 60-120 seconds for recycle period) followed
automatically by a new trial for ignition.
If power fails, the burner will shut down and normal trial for ignition will
begin on call for heat when the power is restored.
Burner
Operation
Continued
CAUTION: Do
not reset the
primary control
more than one
time. If the burner
does not ignite,
contact your
service person.
