Figure 4-35.An electric switch type of relay.
Figure 4-36.Cutaway view of a typical humidifier.
and radiating chamber, and the blower compartment.
Figure 4-37 shows a cutaway view of a typical oil-fired
Like gas-fired units, oil-fired units are also
available with various airflow designs. The model
shown in figure 4-15 is designed with both the
return-air inlet and the warm-air outlet in the top. More
compact models (fig. 4-37) are available with the
return-air inlet at the side or bottom below the radiating
and combustion area. The warm-air outlet is at the top.
A floor furnace is shown in figure 4-38. This type
of oil-fired unit is smaller, lighter in construction, and
is designed to be hung from the floor of the space
served. Only a minimum of clearance is required
below the floor.
Oil burners may be separated into various classes,
such as domestic and industrial. Since domestic oil
burners are used almost universally in warm-air
furnaces, they are the only ones covered in detail in this
Domestic Oil Burners
Domestic oil burners atomize the oil and are
usually electrically power driven and are used in small
central heating plants. They deliver a predetermined
quantity of oil and air to the combustion chamber,
ignite it, and automatically maintain the desired
Domestic oil burners are classified according to
various methods, none of which is entirely satisfactory
because of the overlapping among a great number of
models. Classification may be by type of ignition,
draft, operation, method of oil preparation, or features
of design and construction.
DESIGN AND CONSTRUCTION.One of the
most common types of domestic oil burners is the
pressure-atomizing gun type of burner. Gun type