2
HVAC SYSTEMS AND EQUIPMENT
2.1
HVAC SYSTEMS SELECTION REQUIREMENTS
2.1.1 GENERAL
The HVAC System for a specific project shall be selected through an
engineering economic analysis to ensure that the system is cost effective.
See Paragraph 1.1.6 for this requirement.
2.1.2 EXISTING BUILDINGS
Where an all-air system cannot be used due to physical limitations, VA may
waive the requirement for a life cycle cost analysis. See Article 1.10 for
the waiver of this requirement.
2.2
SPECIAL REQUIRMENTS FOR ALL AIR SYSTEMS
2.2.1 VARIABLE AIR VOLUME (VAV) SYSTEMS
As far as possible, VAV systems shall be used with all air systems, except
for spaces requiring constant air changes/hours, and/or critical pressure
differentials with respect to the adjoining spaces. See paragraph 2.4 for
specific design considerations
2.2.2 INTERIOR ROOMS
Only all-air systems shall be used for interior space to take advantage of
free cooling by an economizer cycle. When the existing exterior rooms become
interior rooms because of new construction or modifications, the HVAC system
for these rooms must be checked and modified to all air systems provided
these rooms are not already served by all air systems. This is required even
though these rooms may not be a part of the new or modification project.
2.2.3 TERMINAL REHEAT SYSTEM
Use of constant volume with terminal reheat systems shall be confined to
areas such as operating rooms, SPD, laboratories, recovery, intensive care,
animal research, autopsy, and BMT patient rooms, recovery rooms, donor rooms,
medical preparation rooms and Spinal Cord Injury.
2.2.4 DUAL DUCT SYSTEM
For dual-duct systems utilizing 100 percent outdoor air, analyze the need for
pre-cooling coils to control humidity during low load conditions.
2.2.5 RETURN AIR FANS
All air-handling units using return air shall be furnished with return air
fans for economizer cycle capability, pressure relationship, and to
facilitate positive control of air balance.
2.2.6 SYSTEM ZONING REQUIREMENTS
2.2.6.1 GENERAL GUIDELINES
The VA criteria for zoning HVAC systems and the selection of the type of air
handling units (AHUs) is based on the specific HVAC requirements of the
medical departments, life cycle cost analysis, and energy conservation. For
existing facilities, considerations listed below could also influence the
selection of HVAC systems.
(a) Space availability for equipment, piping, and ductwork
HVAC DESIGN MANUAL
2-1
HVAC SYSTEMS AND EQUIPMENT
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