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3.2 ALL AIR SYSTEMS
A. SYSTEM FEATURES: The features listed below shall be incorporated in
design unless specific deviations recommended by a designer are
deemed beneficial for this project.
1. An all air system shall comprise of a single duct, horizontal,
draw-thru, chilled water (or direct expansion-DX), variable air
volume (VAV) air handling unit complete with fan, filter, and coil
sections. For roof mounted air handling units, fully weatherized,
penthouse configuration with modular sections shall be provided.
2. Each air handling unit shall be equipped with a return air fan and
an economizer capability of providing "free cooling" during mild
outdoor conditions. The requirement for an economizer cycle can be
dropped if the designer can demonstrate that the provision for an
economizer cycle is not cost effective.
3. The filters shall comprise of a 30% (ASHRAE Test) efficiency
prefilters and 50% to 60% (ASHRAE Test) efficiency afterfilters
banks. The pre and after filters can be located back to back as
one section, in the same frame, on the upstream side of the supply
air fan.
4. Air distribution ductwork complete with ducts, air terminal units,
and supply air outlets shall be used to provide conditioned air to
the spaces. The return air need not be ducted from each room as
the space above the suspended ceiling can be used as return air
plenum. An insulated "Z" duct shall be used to pick return air
from rooms where the partitions extend up to the under side of the
structural ceiling. The exhaust air shall be ducted from each
space to be exhausted. Transfer of supply, return, and exhaust
air, from one occupied area to another, is not permitted without
ducted connections. Exception: Toilets and janitor closets; see
Article 2.
5. Perimeter Heating: Perimeter heat shall be provided for all
locations where winter outdoor design temperature is -17 C (0 F)
and below. If the building thermal envelope is not in compliance
with the limiting parameters outlined in Article 6, ENERGY
CONSERVATION, the perimeter heat shall be required for locations
where winter outdoor design temperature is -6 C (20 F) and
below. Perimeter heating system shall also be used to maintain
winter set back temperature during unoccupied hours of nights and
weekends. The perimeter heating system shall be either in the form
of radiant ceiling panels or finned tube radiation. The radiant
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