Learning Objective: Identify the principles and theory of heating and the
procedures required for installing, operating, maintaining, troubleshooting, and
repairing warm-air heating and hot-water heating systems and associated peripheral
Heat is one of the prime necessities of life. It is as
essential as food, clothing, and shelter. You can have a
very good shelter, but you still need heat to be
comfortable in it. By studying this chapter, you will start
to gain knowledge of what you will be required to know
to become efficient in the Utilitiesman (UT) field.
PRINCIPLES OF HEATING
Learning Objective: Understand the basic principles
and theory of heat, heat measurement, and heat transfer.
Long after people had advanced to the stage of
house building, heating methods had not improved
much. For centuries fires for heating and lighting were
contained in braziers or confined to an unused corner
of a room. The smoke was supposed to escape through
a hole left in the roof of the building during
construction. Of course, a considerable amount of rain
and snow entered the room during bad weather. During
the twelfth century, however, the people in the
northern part of Europe started using crude fireplaces
and flues to replace the brazier and hole-in-the-roof
method of heating. Some of these rudimentary heating
systems still exist in France.
In the thirteenth and fourteenth centuries, the round,
hollow stone chimneys began to be used. At the end of
the fourteenth century, people were using a number of
fireplaces in their homes and grouping the chimneys
together in a vertical, rectangular mass of masonry with
decorative effect. By the end of the Italian renaissance
period, chimneys were in common use.
During colonial days in America, the fireplace
chimneys were a large masonry mass projected
through the center of the roof or were an important
feature of the gable end walls. This general trend is
often followed in architecture today because central
heating, required in places where fires are required 5 or
6 months of the year, makes the chimney an important
feature of a heating plant. There are heating
installations, however, that do not make use of the
masonry chimney and have substituted an
inconspicuous metal smoke pipe. Other types of
heating, such as electrical heating, require no chimney.
Methods and equipment used for heating the places we
live and work have progressed quickly in the last 100
years. This quick advance is due to our understanding
of the principles and theory of heat, which in earlier
times was not yet understood.
THEORY OF HEAT
Heat is a form of energy that is known for its effect.
Heat can be produced or generated by the combustion
of fuels, by friction, by chemical action, and by the
resistance offered to the flow of electricity in a circuit.
However, the particular form of generated heat with
which the heating specialist will be dealing is produced
by combustion. Generated heat is obtained by burning
common types of fuels, such as coal, oil, and gas.
To operate a heating plant efficiently, you must be
familiar with the measurement of heat and how this
heat is transferred from the plant to the space being
heated. The first part of this section is devoted to
measuring temperature; the second part is concerned
with the transfer of heat from the plant to the space
Measurements of temperature and pressure, which
are obtained continuously, are very important factors
in the operation of a heating plant. The degree of
correctness of these measurements directly affects the
safety, the efficiency, and the reliability of the
operation of the heating plant. Although heat and
temperature have a direct relationship, there is also a
distinction between them. For example, a burning
match develops a much higher temperature than a
steam radiator, but the match does not give off enough