COOLING
By Mike Hayes, Applications
Specialist, FläktGroup
www.flaktgroup.com
Mike Hayes offers his top tips and highlights areas
which should be considered to ensure cooling
systems run as smoothly as possible
Non-IT infrastructure plays a crucial role in keeping a data
centre operational and represents a significant proportion
of hardware investment. Employing best practice in the
maintenance and operations of support systems, such as
critical cooling helps to maximise availability and energy
efficiency, ensuring that back-up units kick in when needed.
Charge it right
Refrigerant charges within CRAC units are critical,
and the old school methods of simply charging to sight
glass or gauges are long since passed. More robust methods
including the reading of suction superheat, liquid subcooling
and discharge superheat, throughout the compressor
operating envelope, are all now required.
Overcharging of these systems has become commonplace
and is usually due to a lack of experience and knowledge.
Failure to get this element right can result in compressor
failure. It’s also important to remember that products vary
from one manufacturer to the next, which is why many
develop detailed servicing and maintenance work schedules
tailored to the needs of their product ranges.
1
Clean coils
Cleaning condenser coils is an essential task in any
planned preventative maintenance regime. Depending on
the type of dirt and contaminants that need to be removed,
the coils can be cleaned by one of three methods: chemical
cleaning, manual brushing or a pressure wash. Despite the
simplicity of this procedure, it can often be overlooked by
technicians who don’t fully understand the principles of
close control cooling units and the role they play in a data
centre. If left uncleaned, the coils will inevitably clog up
resulting in refrigerant high-pressure trips and ultimately,
system downtime.
2
Swap out components
It sounds obvious, but parts like air filters and
humidifier cylinders should be replaced regularly. This could
be servicing teams changing the air filters twice a year, and
humidifier cylinders, depending on water quality, two to
four times a year. Old humidifier cylinders prevent optimal
system performance, raising energy usage and costs.
Clogged air filters can lead to system failures, which can be
expensive to rectify.
3
Spread the load
One or two additional units are often specified to
provide backup should any unit fail. To ensure that duplicate
units can function and help meet the cooling load when
needed, these should be used regularly in the same way
normal units are employed. By spreading the load, the risk of
breakdowns in the normal units can also be reduced.
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Secure the network
To implement the above, all the units – including
those for backup – should be networked so the operator
can set them up to work on a rotational basis and control
changeovers. This does also mean that the network cooling
system needs to be protected from cyber attacks. Therefore,
all units, including duplicate ones, should be linked to
the data centre’s IT infrastructure. Solutions that can be
connected to a building’s network via a pCOWEB card, which
restricts access to the units’ IP addresses, and allows the
data centre operator to monitor the system’s security are a
robust option.
5
Protect the power supply
If the power supply to cooling equipment is
interrupted, fans, compressors and humidifiers will stop
working. Therefore, any cooling solution used in data
centres should be able to switch to a different feed in case
of a mains power outage. For example, some units have a
remote start-stop signal that can be connected to a backup
generator via the building management system. Some
systems allow the units to have a dual power supply so they
can run on electricity from a UPS or a generator if needed.
6
Invest in the best
Maintenance is often contracted out to a building
facilities provider based solely on cost. However, while
engineers who have attended short training programmes
such as F-Gas courses can work with air- conditioning and
refrigeration systems, close control units in mission-critical
environments are best maintained by manufacturer-trained
engineers. After all, products vary from one manufacturer
to the next, so it’s important for servicing and maintenance
technicians to have a detailed knowledge of how particular
precision control units work, and to understand their impact
in a mission-critical setting. n
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