if they conform to the requirements of NFPA 90A, "Air Conditioning
and Ventilating Systems". Under no circumstances may combustible
materials be located within the air plenum space. See MIL-HDBK 1008
for more information. In order to consider a ceiling plenum, the A/E
must assure that all conditions of usage are met and will continue to
be met during the life of the system.
d) Duct Smoke Detectors: Duct smoke detectors are not required
in air handling units under 15,000 CFM capacity, or in units serving
one fire area, except that duct smoke detectors are required in air
handling units under 15,000 CFM capacity which are located in
hospitals, schools, and detention facilities which are not
e) Smoke and heat vents: Underwriters' Laboratories (UL)
listed smoke and heat vents shall be provided in roofs of buildings
containing materials having high heat-release potential, such as
warehouses, flammable liquid storage and handling facilities and
other extra hazard occupancies. NFPA 204, "Smoke and Heat Venting
Guide", provides guidance.
VAV HVAC Systems
VAV HVAC Systems are best suited for use in spaces always requiring
cooling. VAV systems shall only be used if economical to install and
operate and if ACTIVITY personnel can and will maintain the system
satisfactorily. The system must always provide the required fresh
air into each occupied space, even when operating at minimum
conditions. The A/E must prepare a tentative maintenance schedule to
which the ACTIVITY must subscribe (in writing) in order for VAV to be
acceptable. The A/E must certify in writing and produce calculations
to prove adequate ventilation in accordance with ASHRAE 62 at all
times; RH and air distribution must be controlled at all times.
VAV Systems shall have the following limitations:
Less than 10,000 CFM, 1.5 inches ESP.
1 to 15 boxes.
c) Pressure dependent VAV boxes generally with terminal wall
mounted DDC controls. (No pneumatic controls as VAV boxes.)
Manufacturers of VAV boxes are to provide linkages and controls.
d) Separate HW heating system with unoccupied (nighttime)
shutoff of air system.
No return fans.
Ride fan curve under 3,000 CFM.
g) No fan powered terminal boxes unless air is filtered.
Provision must be made to easily change filters and maintain the VAV
boxes without maintenance personnel having to remove panels to climb
above suspended ceilings.
Linear slot diffusers are recommended.