Rule 656.
(1) If
power exhaust ventilation is to be used, there shall be an air supply equal to
the amount exhausted, especially in areas that house combustion
equipment.
(2) Fan and air-handling
equipment used for recirculating air in more than 1 room or a single area shall
be located in a room that is cut off from other portions of the building by
construction that has not less than a 1-hour-fire-resistance rating. A room
that houses fans and air-handling equipment shall not be used for any
combustible storage.
(3) A duct or
plenum which employs mechanical means for the movement of air and which is used
for heating and ventilation, including warm air heating systems, plain
ventilating systems, air-conditioning systems, or exhaust systems, shall be
constructed entirely of noncombustible material.
If a duct or plenum of an existing system is constructed,
wholly or in part, of combustible materials, it shall be reconstructed entirely
of noncombustible materials, if possible. If revamping or reconstruction is
impractical due to design or construction, the inspecting authority may accept
the existing installation if heat-actuated fire dampers are installed in each
return air duct opening from every room or space.
(4) A heat-actuated fire damper shall be
installed on the discharge side of each recirculating fan unit that serves more
than 1 room or a single area and, where practicable and feasible, there shall
be an approved thermostatic device that has a setting of not more than 125
degrees Fahrenheit located in the system at a suitable point in the return air
duct ahead of the fresh air intake, actuation of which shall open the
electrical circuit that supplies the fan motor. If it is impracticable to
locate a thermostatic device ahead of the fresh air intake, an approved heat or
smoke-actuated device, actuation of which will open the electrical circuit that
supplies the fan motor, shall be located at a suitable point in the air duct on
the discharge side of the fan.
(5)
If an existing system utilizes corridors or exitways as return air plenums, the
system shall be revamped to eliminate the utilization of corridors or exitways
as return air plenums. If revamping is impractical due to design or
construction, the inspecting authority may accept the existing system if an
approved smoke detector is installed in each separated area of the corridors or
exitways to automatically open the electrical circuit that supplies the fan
motor. A smoke detector shall incorporate visual or audible signals to indicate
any trouble that would interfere with the proper operation of the smoke
detector. A stairway shall not be used as a return air
plenum.
