Rittal Liquid Cooling Package 89
18 Frequently Asked Questions (FAQ)
EN
Can the Liquid Cooling Package be operated together
with the CPU cooling solution?
A combination of direct CPU cooling with water and
the Liquid Cooling Package is always possible. De-
pending on the computer system, only up to 70% of
the total heat loss is removed through the water
heatsinks with direct CPU cooling. In cases of high
cooling output requirements, this means that a com-
bination of systems is even necessary. Please re-
quest our documentation for individual projects sep-
arately.
In case a pipe should break or burst, how is water en-
try into the server rack avoided?
Because the components are carefully chosen, it is
practically impossible for a pipe to break. The base
unit of each LCP serves as a collecting tray for wa-
ter, and is capable of collecting either condensate
or leaked water. Through the physical separation of
the Liquid Cooling Package from the server enclo-
sure, it is always ensured that no water can enter
into the server area. Additionally, the integrated
leakage sensor reports even the smallest leak vol-
umes to allow for a rapid response.
Why does the LCP Rack offer the opportunity of cool-
ing either one or two enclosures?
The most important design principle was a flexible
cooling system which would correspond to the enor-
mous volume of air required by a modern server.
Because of the horizontal cooling possibility, op-
tions for "right", left" or "both-sided" cooling arise in
combination with the chosen fans. Cooling a server
rack with two Liquid Cooling Packages has the ad-
vantage of complete system redundancy without
further installation of 482.6 mm (19") equipment (see
section 3.6.1 "Creation of redundancy in the LCP
Rack").
In which applications and situations should an air/wa-
ter heat exchanger system be used?
Whenever the cooling output of the room air condi-
tioning system is not sufficient to handle the heat
loads of current high performance servers. With an
optimal design in a newly planned data centre, this
limit is at about 1,000 – 1,200 W/m²; in older data
centres, it is often significantly below that. At best, a
maximum of 4 kW per rack needs to be removed. By
contrast, racks which are filled with blade servers
reach up to 17 kW. But the Liquid Cooling Package
represents a possible solution even in applications
where there is no existing air conditioning system. In
combination with Rittal recooling systems, even cli-
mate control solutions for high performance cluster
systems can be created.
What additional infrastructure is required to operate
the system?
In addition to the Liquid Cooling Package, pipes to
the individual enclosures and a system for generat-
ing the cooling water are required. With single en-
closures, a direct connection with the cooling water
is sufficient. With multiple enclosures, a cooling wa-
ter distribution system, similar to a central heating
distribution system, should be provided. To a great
degree, this infrastructure corresponds to that
which is already used in a conventionally air condi-
tioned data centre. The "cold" water is provided by
water chillers (with adequate redundancy, especial-
ly in regard to the pumps). The water is distributed
over a cooling water network in the data centre to
fan coil or ceiling cooling units.
What key disadvantages of today's air-cooled solu-
tions are remedied by water cooling?
The chief problem of conventional cooling involves
directing large amounts of cool air through raised
floors, suspended ceilings and within the room. Of-
ten, because of complex flow conditions, the cold
air does not reach the servers in sufficient quanti-
ties. There is actually enough cold produced; often,
the cooling output from raised floor systems lies far
above the electrically connected load of the unit,
which needs to be cooled. In spite of this, the cool-
ing is insufficient. This effect is explained by the fact
that the cooling air is already warmed too much
through recirculation on its way to the server. By us-
ing water to remove the heat out of the enclosure, an
excellent separation between cold air and removed
thermal energy is achieved. Because of its material
characteristics, water can transport thermal energy
almost 4,000 times "better" than air. Small pipes are
capable of transporting very large quantities of heat.
Can accessories and other equipment from 482.6 mm
(19") enclosures be used in conjunction with the
Liquid Cooling Package?
The Liquid Cooling Package and the accompanying
server enclosure are standard products within the
Rittal family of enclosures. All components and ac-
cessory parts can be used without limitation.
Up to what depth may servers be installed?
Modern server systems may be up to 800 mm deep.
Because of that, it is recommended that the
482.6 mm (19") level in the enclosure be installed so
that the same distance remains to the door in front
and in back. In combination with the space on the
side between the 482.6 mm (19") level and the
Liquid Cooling Package, sufficient room for the air
which is fed or emitted is achieved. The side open-
ings do not need to be completely open throughout
their depth.
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