1402
Modern Refrigeration and Air Conditioning
weighing the ice batch produced, and calculating the total
daily production potential so these values may be compared
with manufacturer specifications. (51)
capillary action. The movement of a liquid substance
between two solid substances due to the molecular adhesive
forces between the solids overcoming the liquid’s cohesive
forces. (4)
capillary tube. A refrigerant metering device consisting of a
length of seamless tubing with a small and precisely formed
inside diameter. This tube acts as a constant throttle on the
refrigerant flow and a constant pressure drop. (16)
carbon dioxide (CO2). A gaseous, nontoxic combination of
carbon and oxygen that results from combustion and respi-
ration. (22)
carbon monoxide (CO). A deadly, odorless, colorless gas
produced by the combustion of fuel. (22)
carburizing flame. A torch flame that has too much acet-
ylene and not enough oxygen. It usually generates a lot of
smoke. (4)
cascade refrigeration system. A multistage refrigeration sys-
tem that consists of two or more separate refrigeration sub-
systems that work together to multiply cooling effect. (44)
Category I furnace. A negative-pressure, noncondensing
furnace with a flue gas temperature of at least 140°F (60°C).
Many furnaces used in residential heating are Category I
furnaces. (35)
Category II furnace. A negative-pressure, condensing fur-
nace that requires special vent materials. Category II fur-
naces are rarely used in residential heating. (35)
Category III furnace. A positive-pressure, noncondensing
furnace that is typically vented with stainless steel piping.
Category III furnaces are rarely used in residential heating. (35)
Category IV furnace. A positive-pressure, condensing
furnace with a flue gas temperature that is less than 140°F
(60°C). Category IV furnaces are high-efficiency furnaces
with secondary heat exchangers. (35)
cathode. In electronics, a negatively charged segment of a
semiconductor, consisting of an N-type material, such as on
a diode. (11)
Celsius scale. A temperature scale used in SI system. At sea
level, the boiling point of water is 100°C, and the freezing
point of water is 0°C. (1)
center punch. A type of punch used to mark the center of a
hole to be drilled. (3)
central air conditioning. A centrally located system that
is capable of providing heating, cooling, humidity control,
ventilation, and air cleaning to multiple spaces. (26)
central humidifier. A humidifying unit that is incorporated into
a central HVAC system through bypass ductwork or by being
installed directly into the return or supply ductwork. (28)
centralized computer control. A building system con-
troller that consists of one or more centralized computers
that make control decisions based on operating data, pro-
grammed information, and data already stored in computer
memory. (40)
centrifugal compressor. A compressor consisting of an
impeller with radial blades and a volute casing. As the rotor
spins, it flings refrigerant vapor outward, where it com-
presses against the volute casing. (15)
centrifugal force. A force that acts outward from the center
of rotation. (15)
centrifugal switch. An electrical device mounted on the
end of a motor shaft that disconnects the start windings
from the motor circuit. The switch is opened and closed by
centrifugal force. (12)
charge compensator tank. A storage vessel used by some
heat pumps during the heating mode to store extra liquid
refrigerant. (34)
charging. Adding refrigerant to a refrigeration system. The
proper amount of refrigerant is typically specified in terms
of its weight. (8)
charging cylinder. A small refrigerant cylinder, usually hold-
ing 5 lb of refrigerant or less, that is used for adding precise
amounts of refrigerant, typically to domestic appliances. (8)
Charles’ law. A law that states the direct proportional rela-
tionship between volume and temperature, provided the
pressure remains constant. (1)
check valve. A valve that permits fluid flow in only one
direction. (16, 47)
chest freezer. A freezer unit that has its door on the top of
the unit. (17)
chilled water system. A cooling system that uses a loop of
chilled water instead of forced air to provide cooling to a
conditioned area. Sometimes called a chiller system. (26)
chiller. A cooling system that uses a loop of chilled water
instead of forced air to provide cooling to a conditioned
area. Sometimes called a chilled water system. Chiller may
also sometimes specifically refer to the evaporator chilling
the water. (26)
chlorofluorocarbons (CFCs). Refrigerants that are com-
posed of chlorine, fluorine, and carbon. CFCs are a major
cause of ozone depletion. (6)
circuit breaker. An electrical protection device that auto-
matically opens a circuit when the current exceeds a pre-
determined level. The increased magnetic effect of the
current surge causes a spring-loaded switch to trip and
break the circuit. (10, 13)
circulating pump. A motor-driven pump that circulates
heated water through a hydronic system. (33)
clamp-on ammeter. An ac ammeter that senses and mea-
sures current based on the magnetic field produced by
alternating current as it flows through a conductor. Unlike
in-line ammeters, clamp-on ammeters do not require break-
ing the circuit for measurements. (14)
Clean Air Act (CAA). A US federal law that seeks to limit
ozone depletion and air pollution. Section 608 provides
guidelines for recycling refrigerants and restrictions on
releasing refrigerants into the atmosphere. (6)
clean room. A room in which the environment is highly
maintained. The temperature, humidity, and air quality are