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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.