Symbols - Honeywell AUTOMATIC CONTROL Engineering Manual

CHILLER, BOILER, AND DISTRIBUTION SYSTEM CONTROL APPLICATIONS
• Refrigerant head–The pressure difference between
compressor suction and discharge pressures or the
temperature difference between condensing and
evaporating temperatures.
• Static head–The pressure of a static fluid expressed as the
height of the fluid or the height of another fluid it would
support.
Non-symmetrical loading–Diversity in multiple load systems,
where individual loads operate at different times or
loading from the others.
Primary - Thermal production water elements such as chillers
and boilers. Thermal production air elements such as
air handlers.
Rangeability–The ratio of maximum to minimum flow of a valve
within which the deviation from the inherent flow
characteristic does not exceed some stated limits.

SYMBOLS

The following symbols are used in the system schematics following. These symbols denote the nature of the device, such as a
thermometer for temperature sensing.
56
56
NORMAL
AUTO
ENGINEERING MANUAL OF AUTOMATIC CONTROL
CONTROLLER, TEMPERATURE
SENSOR, TEMPERATURE
LOW LIMIT
HIGH LIMIT
MANUAL RESET NOTATION
INSERTION TEMPERATURE SENSOR
TEMPERATURE SENSOR,
AVERAGING
TEMPERATURE CONTROLLER,
MANUAL RESET, SAFETY LOW LIMIT
MANUAL MULTI-STATE
COMMAND (ON-OFF-AUTO)
STATUS POINT
ON
63 VALUE POINT (% LOAD)
74 COMMANDABLE VALUE
3-WAY VALVE WITH ACTUATOR
2-WAY VALVE WITH ACTUATOR
DAMPER WITH ACTUATOR
Secondary - Thermal consumption water elements such as AHU
coils. Thermal consumption air elements such as VAV
boxes.
Superheat–The additional heat contained in a vapor at a
temperature higher than the saturation (boiling)
temperature corresponding to the pressure of the vapor.
Surge–A condition where refrigerant reverses flow approximately
every two seconds creating excessive noise, vibration,
and heat. Surge is caused by insufficient pumping head
to meet the rise in pressure from evaporator to condenser.
Symmetrical loading–Diversity in multiple load systems, where
individual loads operate at the same time and same
percentage loading as the others. Diversity factor = 1.
Variable speed pumping (VSP)–A pumping system where the
flow/pressure is varied by changing the pump speed.
FAN
PRESSURE CONTROLLER,
HIGH LIMIT CUT-OUT,
MANUAL RESET
PRESSURE SENSOR
1.8
COOLING COIL
HEATING COIL
FILTER
PUMP
SOLENOID VALVE
SMOKE DETECTOR
(NFPA SYMBOL)
PROPELLER EXHAUST FAN
298
M10437