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Figure 4-39.—High-pressure gun type of oil burner | Up
Utilitiesman Basic Volume 02 - Manual for electric, plumbing, water and other utilities | Next
Figure 4-43.—Typical forced warm-air control system |
Figure 4-41.—Vertical-rotary burner of the vaporizing or wall
flame type.
Horizontal Rotary Type.—The horizontal rotary
type was originally designed for industrial use;
however, sizes are available for domestic use. It has a
wider range of fuel-burning capacity than the
high-pressure gun type and can accommodate heavier
grades of fuel. Figure 4-42 shows this type of burner.
The major parts of the burner are the housing, fan,
motor, fuel tube, and rotating atomizing cup. The
atomizing cup and fan are driven at the same speed by a
directly connected electric motor. Oil is fed through
the fuel tube to the inner surface of the atomizing cup.
The oil spreads over the surface of the cup, which turns
at 3,450 revolutions per minute (rpm). It then flows to
the edge of the cup where it is thrown off. The whirling
motion and the resulting centrifugal force separates the
oil into fine particles, as it leaves the cup. Primary air
supplied by the fan is thrown in around the outer edge
of the rotating cup and given a whirling motion in the
direction opposite that of the oil. The streams of air and
oil collide and thoroughly mix, as they enter the
combustion chamber.
OIL BURNER CONTROLS.—The purpose of
oil-burner controls is to provide automatic, safe, and
convenient operation of the oil burner. The system is
designed to maintain the desired room temperature, to
Figure 4-42.—A horizontal-rotary oil burner.
start the burner as required, and to ignite the fuel to
initiate combustion. However, in case trouble arises
during operation, the burner must be stopped and
further operation prevented until the trouble has been
corrected.
Oil-burner controls are essentially the same as
stoker or gas controls. The only difference is that the
oil burner has, in addition, two ignition electrodes and
a primary or safety control. A diagram of a typical
forced warm-air control system is shown in figure
4-43.
Primary Control.—The burner primary control is
electrically connected between the thermostat and the
burner, as shown in figure 4-43, and it performs several
functions. The primary control closes the motor and
ignition circuits when the thermostat calls for more
heat. It breaks the motor circuit and stops the burner
when the motor first starts if the fuel fails to ignite or if
the flame goes out. The control prevents starting of the
burner in case of electrical failure until all safety
devices are in the normal starting position.
An interior view of a primary control is shown in
figure 4-44. This control device is also equipped with a
high-temperature limit control. This control shuts
down the heating plant whenever the temperature of
the furnace becomes excessive. For example, if the
thermostat is exposed to a blast of cold air for a long
period of time, the heating plant could run long enough
to become overheated to the point of severe damage or
external fire if it was not for this high-temperature limit
control.
4-26
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