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not often monitored, yet is extremely
important. for example, if 55˚f is
being supplied (fairly typical), the
data center is more than 5˚f below
the recommended minimum
temperature for data processing
equipment, per ashrae
environmental guidelines. however,
this low temperature is often not a
problem for it equipment because
by the time the airflow reaches the it
equipment, it is typically a much
higher temperature.
how does this Δt occur? often,
supply air can become heated
before it enters the computer room
from under the floor. for example,
perforated floor tiles located too
close to Crahs can actually draw
warm air into the space beneath the
floor due to the low pressure being
created by high velocity supply air
(the venturi effect). additionally,
underfloor obstructions can also
create vortices which result in low
pressure pockets that pull air from
outside of the room into the
underfloor space. this unwelcome
air mixes with the supply air and is
another factor in increasing the
temperature before it even
evacuates through perforated tiles
into the data center.
even once the supply air enters the
computer room, it is subject to
conditions which can further increase
the temperature. openings in server
racks – either open rack mount
spaces or unsealed areas around the
perimeter of the equipment
mounting area – can allow the server
waste air to leak back into the cold
aisle and raise the temperature of
the supply air. the problems caused
by inadequate airflow due to