Building Design and Construction Handbook - Merritt - Ventech!

13.4 SECTION THIRTEEN
Evaporator. A cooling coil in a refrigeration system in which the refrigerant is
evaporated and absorbs heat from the surrounding fluid (airstream).
Exfiltration. Unintentional loss of conditioned supply air by leakage from ductwork,
rooms, spaces, etc., that is to be considered a load on the air-conditioning
system.
Film Coefficient (Surface Coefficient). Heat transferred from a surface to air or
other fluid by convection per unit area of surface per degree temperature difference
between the surface and the fluid.
Furnace, Warm-Air. Heating system that uses a direct- or indirect-fired boiler to
produce warm air for heating.
Grille. A metal covering, usually decorative, with openings through which supply
or return air passes.
Head. Pressure expressed in inches or feet of water. A head of 12 in, or 1 ft, of
water is the pressure equivalent to a column of water 12 in, or 1 ft, high. See
also Inch of Water below.
Heat, Latent. Heat associated with the change of state (phase) of a substance,
for example, from a solid to a liquid (ice to water) or from a liquid to a gas
(water to steam vapor).
Heat, Sensible. Heat associated with a change in temperature of a substance.
Heat, Specific. Ratio of the thermal capacity of a substance to the thermal capacity
of water.
Heat, Total. Sum of the sensible and latent heat in a substance above an arbitrary
datum, usually 32�F or0�C.
Heat Capacity. Heat energy required to change the temperature of a specific
quantity of material 1�.
Heat Pump. A refrigerant system used for heating and cooling purposes.
Heat Transmission Coefficient. Quantity of heat (usually Btu in the United
States) transmitted from one substance to another per unit of time (usually 1 hr)
through one unit of surface (usually 1 ft 2 ) of building material per unit of temperature
difference (usually 1�F).
Heater, Direct-Fired. A heater that utilizes a flame within a combustion chamber
to heat the walls of the chamber and transfers the heat from the walls to air for
space heating, as in a warm-air heater.
Heater, Unit. A steam or hot-water heating coil, with a blower or fan and motor,
used for space heating.
Heating. The process of transferring heat from a heat source to a space in a
building.
Heating, District. A large, central heating facility that provides heat from steam
or hot water to a large number of buildings often under different ownership.
Heating, Radiant. Heating by ceiling or wall panels, or both, with surface temperatures
higher than that of the human body in such a manner that the heat loss
from occupants of the space by radiation is controlled.
Heating, Warm-Air. A heating system that uses warm air, rather than steam or
hot water, as the heating medium.
Heating Surface. Actual surface used for transferring heat in a boiler, furnace,
or heat exchanger.