MIL-HDBK-1003/3
2.3
Noise and Vibration Control. For noise and vibration
control, refer to Army TM 5-805-4, Noise and Vibration Control
for Mechanical Equipment, Chief of Naval Operations Instruction
(OPNAVINST) 5100.23, Navy Occupational Safety and Health (NAVOSH)
Program Manual, and ASHRAE Systems Handbook. Limit HVAC and
ancillary equipment noise levels below those requiring a hearing
conservation program as defined in Department of Defense
Instruction (DODINST) 6055.12, DOD Hearing Conservation Program.
2.4
System and Equipment Performance. Refer to
MIL-HDBK-1190, Facility Planning and Design Guide. For size and
selection criteria of systems and equipment, refer to ASHRAE
Equipment Handbook. HVAC systems shall be able to dehumidify
supply air under loading conditions, provide reliable operations,
and tolerate reasonable variations in chilled-water temperatures.
Air conditioning systems generally operate at part load
conditions most of the time. This is particularly true of
comfort air conditioning systems which often operate at less than
50 percent of their design load capacity for more than 50 percent
of the time. Since high part load efficiencies are desirable to
conserve energy, the selection of equipment and step starting and
sequencing controls shall be made with an emphasis on reducing
life-cycle costs at part load conditions. Verify and document
the equipment operation in accordance with ASHRAE Guideline 1,
Commissioning of HVAC Systems.
2.4.1
Cooling Systems
2.4.1.1
Central Air Conditioning Systems. Use these systems
for applications where several spaces with uniform loads will be
served by a single apparatus and where precision control of the
environment is required. Cooling coils can be direct expansion
or chilled water. Select air cooled or evaporative condensers,
cooling towers, and ground-loop systems based on life cycle
economics considering operating efficiencies and maintenance
costs associated with outdoor design conditions and environment,
e.g., high ambient temperatures and dusty conditions could
adversely impact the operation of air cooled condensers.
Consider temperature rise of chilled water supply when selecting
chilled water coils, especially for applications requiring
precision humidity control.
2.4.1.2
Unitary Air Conditioning Systems. These systems should
generally be limited to loads less than 100 tons. Unitary
systems are packaged in self-contained or split configurations.
Self-contained units incorporate components for cooling or
cooling and heating in one apparatus. Thermostatic expansion
valves are preferred over capillary tubes and orifices for
refrigerant control when available as a manufacturer's option
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