Honeywell Design and Application Technical Reference Manual page 214

APPENDIX
Dilution— The reduction of airborne
concentration of contaminants through an
increase in outdoor air supplied to the
area.
Discharge or Supply Air— Air which has
been treated (heated or cooled) before
being supplied to the conditioned area or
room.
Economizer— Economizer controls provide
"free cooling" during the cooling season
by measuring the temperature or enthalpy
of outside air. Outside air is used for
cooling if it is sufficiently cool and dry.
This reduces the usage of the mechanical
cooling equipment and reduces cooling
costs.
Electric Control— A control circuit that
operates on line or low voltage and uses
a mechanical device, such as a
temperature-sensitive bellows, to perform
control functions, such as actuating a
switch or positioning a potentiometer. The
controller signal typically operates or
positions an electric actuator or may
switch an electrical load directly or
through a relay.
Electronic Control— A control circuit that
operates on low voltage and uses solid-
state components to amplify input signals
and perform control functions, such as
operating a relay or providing an output
signal to position an actuator. The
controller typically furnishes fixed control
algorithms based on the circuitry inside
the solid-state components.
Electromechanical Controller— A control
device such as the H205 which is
constructed of moving parts instead of
solid state or electronic components.
Typically more calibration and
replacement is required of these devices
than solid state controllers.
63-8594-02 Honeywell Economizers
Enthalpy— A measure of the total energy
content of air based upon both
temperature and moisture content. When
selecting air for cooling it is a better
measurement than solely temperature.
Final Control Element— A device such as a
valve or damper that is used to change
the value of the manipulated variable.
Positioned by an actuator.
Greenhouse Gas Emissions— Gases in an
atmosphere that absorb and emit
radiation within the thermal infrared
range. This process is the fundamental
cause of the greenhouse effect. The main
greenhouse gases in the Earth's
atmosphere are water vapor, carbon
dioxide, methane, nitrous oxide, and
ozone
Indoor Air Quality (IAQ)— The
characteristics of the indoor climate of a
building, including the gaseous
composition, temperature, relative
humidity, and airborne contaminants.
Integrated Economizer— An economizer
control circuit that replaces the inefficient
"wild" economizer by only enabling
outside air for cooling when there is a call
for cooling from the commercial
thermostat and allowing for economizing
and mechanical cooling at the same time.
.
Manipulated Variable— The quantity or
condition regulated by the automatic
control equipment to cause the desired
change in the controlled variable.
Mixed Air— The combination of outdoor and
return air prior to mechanical cooling or
heating.
Modulation— A control mode with minute
increments and decrements.
208