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Chapter 17 Constructing Structures
from leaking into the home. Wastewater
systems have a network of vents to pre-
vent the water from being drawn out of the
traps. The vents also allow sewer gases to
escape above the roof without causing any
harm.
Homes that use natural gas have a
third type of plumbing. Gas lines carry
natural gas to furnaces, stoves, water heat-
ers, and other appliances. Shutoff valves are
installed at the entrance and at the major
appliances.
Climate-control systems
In many homes, the climate-control
system is used to heat the building in
winter and cool it in summer. This can be
done with a single unit or with separate
heating and cooling units. Heating systems
can directly or indirectly heat the home. In
a direct heating system, the fuel is used in
the room to be heated. Direct heating might
use a stove or a fireplace that burns wood
or coal.
Other direct heating methods use elec-
trical power. These systems use resistance
heaters installed in the walls or along the
baseboards. Also, ceiling radiant wires or
panels might supply the heat.
Indirect systems heat a conduction
medium, such as air or water. This medium
carries the heat from a furnace to the rooms.
The heat is then given off to the air in the
room. See Figure 17-21. The energy sources
for these systems are electricity, coal, oil,
wood, natural gas, or propane.
Furnaces that heat air as a conduc-
tion medium are called forced-air heating
systems. Forced-air furnaces draw air from
the room. This air is heated as it moves
through the furnace. A fan delivers the
heated air through ducts to various rooms.
Hot water heating uses water to carry
the heat. The water is heated in the furnace,
pumped to various rooms, and passes
through room-heating units that have
metal fins surrounding the water pipe. The
fins dissipate the heat into the room.
Some homes are heated with active or
passive solar-energy systems. Passive solar
systems use no mechanical means to col-
lect and store heat from the Sun. Active
solar systems use pumps or fans to move a
Bathroom
Meter
Sink Sink
Dishwasher
Toilet
Cold water Hot water Shutoff
Sink
Shower
Washer
Water heater
Curb
valve
Kitchen Utility Room
Tub
Figure 17-20. The potable-water system for a home. Each fixture has a shutoff valve.