MIL-HDBK-1003/3
2.2.6.2
Direct Digital Controls (DDC). Use direct digital
controls where justified by life cycle cost for new and major
replacement HVAC systems. Verify that activity operating and
maintenance personnel will use DDC by contacting the
EFD or EFA design manager or project leader.
2.2.6.3
Temperature Control Drawings and Specifications.
Comply with NFGS-15972, Direct Digital Control Systems or
NFGS-15971, Space Temperature Control Systems. Refer to par.
4.1.5 for information required on drawings.
2.2.6.4
Automatic Control Valves. Use three-way mixing and
diverting valves only for two-position switching of water flow
and three-way diverting valves for modulating control of cooling
tower water. Use two-way modulating valves and variable flow
pumping for other automatic control of water flow to achieve
energy efficient systems. Three-way valves provide inaccurate
control and at mid position tend to pass greater than design
flow.
2.2.7
Energy Monitoring and Control System (EMCS). EMCS,
which is also called Utility Monitoring and Control System
(UMCS), is not a unique system but is a special application of a
DDC system. New buildings will provide energy management
functions by adding these programs to the DDC system. If an
existing EMCS is to be expanded, do so only when the EMCS is
proven functional and then comply with Army Technical Manual (TM)
5-815-2, Energy Monitoring and Control Systems (EMCS), otherwise
design a DDC system with energy monitoring functions. Do not
provide terminal cabinets for a proposed EMCS.
2.2.8
Instrumentation. Where instruments are required for
adjustments only and are not essential for normal operation,
provide an arrangement to temporarily connect instruments without
stopping or draining the system. Comply with Table 2.
2.2.8.1
Indicating Instruments. Specify ranges of operation
which give an indication of variation in operating conditions.
Measuring instruments shall be provided near automatic control
devices, such as thermostats, humidistats, and pressure switches,
to facilitate adjustments and testing of the control device. Use
indicating types only, unless a permanent operational record is
desired.
2.2.8.2
Recording Instruments. Provide recording instruments
only where a permanent record is required to analyze operating
costs or effects on process applications. If a DDC system is
used, this function can be accomplished through software
programs.
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