change operating schedules, receive trends and
alarms, and allow storage, modifications and
downloading of control programs. This guide
specification can be used to acquire a direct
digital control system that consists of:
DDC of HVAC equipment with graphic operator work
station. The operator workstation can be located in
the building (directly connected to a communications
LAN) or at a remote site (connected to the digital
controller through a LAN or modems and a telephone
line).
The DDC systems should have notebook computers,
hand-held terminals, or panel mounted displays and
keypads for direct connection to the digital
controllers.
If there are questions on the design of direct
digital control systems, contact the Engineering
Field Division, Naval Facilities Engineering Command
Mechanical Engineering Branch, or the Naval
Facilities Engineering Service Center.
**************************************************************************
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NOTE: Show the following information on project
drawings:
1. Mechanical Flow Drawing: Show relative position
of all individual HVAC components, controller inputs
(temperature sensors, pressure sensors, equipment
proofs, override buttons, etc.), controller outputs
(actuators, valves, dampers, etc.), and hard wired
safeties (smoke detectors and freeze protection
thermostats). On the same drawing show a simple
points list. For example:
Equipment
VAV Air Handling Unit
Supply Fan Status - Amperage
AI
Supply Air Temperature
AI
Return Air Temperature
AI
Duct Static Pressure
AI
Chilled Water Valve
A0
Mixed Air Damper Control
AO
Supply Fan Variable Frequency Drive Speed
AO
Supply Fan VFD Status
DI
Supply Fan Start/Stop
DO
VAV Box
Space Temperature
AI
Setpoint Adjustment
AI
VAV Box Airflow - CFM
AI
VAV Box Supply Temperature
AI
VAV Box Damper
AO
VAV Box Reheat Coil
AO
Pushbutton Override
DI
SECTION 15910N
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