(b) Two opposed blade power operated dampers, one (normally open) located at
the exhaust louver and one (normally closed) located in the sheet metal
plenum wall to heat room with waste heat when engine is running. A room
thermostat shall modulate the two dampers to maintain a minimum room
temperature of 15 degrees C (60 degrees F).
(c) Supply air intake shall be large enough to provide make-up air for the
radiator exhaust, and the room ventilation. The intake shall have a normally
open motor operated damper. Damper shall open whenever the generator or room
ventilation fan is energized.
(d) Size the exhaust fan so the combined static pressure loss through the
intake and exhaust louvers, and motor operated dampers does not exceed 63 Pa
(0.25 inch of water).
2.10.6.5 RADIATOR AND FAN REMOTE
When the radiator and fan are installed remote to the engine-generator, do
the following:
2.10.6.5.1 Provide two exhaust fans to ensure the following:
(a) Room Ventilation: The room ventilation fan (capacity: 15 Air Changes/hr.)
shall operate either manually or thermostatically when the space temperature
exceeds 29 degrees C (85 degrees F).
(b) An additional exhaust fan shall operate only when the emergency generator
is running and the space temperature exceeds 29 degrees C (85 degrees F)
2.10.6.5.2 Supply air intake shall be large enough to provide make-up air for
the two exhaust fans and the combustion air. The intake shall have a normally
open motor operated damper and shall open whenever generator or either
exhaust fan is energized.
2.10.6.5.3 Louvers shall have drainable type blades and shall be furnished
under architectural specifications. Louvers shall be sized to provide the
required air for the two exhaust fans. See Article 1.8 for additional
information.
2.10.7 TRANSFORMER ROOMS (VAULTS) AND ELECTRIC CLOSETS
2.10.7.1 GENERAL
Maximum indoor temperatures of 39 degrees C (104 degrees F) shall be
maintained in transformer rooms (Vaults) and electrical closets with dry type
transformers. Small electrical closets without any heat producing devices,
such as, dry type transformers, need not be cooled or ventilated. Any pipe or
duct system foreign to the electrical installation shall not pass through an
electrical room or a closet.
2.10.7.2 HVAC SYSTEMS
To prevent excessive heat build up in transformer rooms, provide a dedicated,
thermostatically controlled, mechanical ventilation or cooling system. The
requirement of a dedicated system can be waived if the room is served by a
building HVAC system that operates 24 hours a day. Design the ventilation
system to maintain the space temperature using the outdoor summer design
temperature 1 percent value listed in the ASHRAE Weather Data.
HVAC DESIGN MANUAL
2-29
HVAC SYSTEMS AND EQUIPMENT
Previous Page
