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SCS Series Manual —
P/N 15712:L 7/18/16
Concepts of Smoke Control
General System Components
2.4.1 HVAC Equipment
HVAC Systems
Whether serving the dual purpose of maintaining the environmental conditions in the building and controlling smoke in a fire situation (Non-
dedicated System), or the sole purpose of controlling smoke (Dedicated System) - HVAC systems can usually be adapted for smoke control.
When used for smoke control applications, HVAC systems must have the following capabilities:
•
Supply outside air to a space,
•
Return air from a space,
•
Exhaust air from a space to the outside.
Some HVAC systems can provide these capabilities without modification.
An HVAC system can consist of nothing more than a fan in a housing, such
as a roof-mounted exhaust fan, or it can be a more complex system with
ductwork, supply air outlets, return air inlets, fresh air intakes, humidifiers,
filters, heating and cooling coils, preheat coils, and dampers. Examples of
commonly used HVAC units and their effects on smoke control are
explained below:
Individual Floor Units.
Air-handling units of this type usually serve one
floor or a portion of a floor. These units may or may not have separate sup-
ply and exhaust fans. Individual floor units can be utilized in a smoke con-
trol system as long as they are capable of providing sufficient outside air
and exhaust capability.
Central System.
Centralized equipment is usually employed to provide
HVAC functions to multiple floors of a building. These types of systems
may require dampers for the supply and exhaust shafts at each floor. Damp-
ers at each floor for the exhaust shaft provide the capability to exhaust
smoke from the fire floor while closing the dampers for all other floors.
This prevents the unwanted movement of smoke to other floors that the unit
serves. Dampers at each floor for the supply shaft provide the capability to
pressurize the floors surrounding the fire floor while closing the dampers
for all floors where pressurization is not desired.
Induction Units.
Induction-type air-handling units are usually used in con-
junction with a central HVAC system which supplies high-pressure air to
the induction units. Induction units are located around the outside of a
building and are used to condition the air for areas around the perimeter of
the building. Room air is then drawn into the induction unit and mixed with
the primary air from the central system and returned to the room. Induction
units serving a fire area should be shut down or the primary air from the
central system should be closed off.
Figure 2.7 Individual Floor Units
Figure 2.8 Central HVAC System