While split systems are often used in small computer server rooms, correct sizing and system design is of paramount importance,
writes Gerry Hooper, technical director of EDC International
WHILE in many instances small computer installations do not need full, close control air conditioning, it has to be remembered that the ac requirement in these situations is far more critical than in say an office, shop or restaurant, where the consideration is for the comfort cooling of people. Yes, I’m afraid it is once again that old scenario where the driver of a refrigerated lorry can be hot in his cab but the frozen peas behind him have to be looked after and maintained at the correct temperature!
Some split systems are suitable for small server rooms but correct sizing and system design is of paramount importance if the installation is to satisfy the needs of the end user – to keep the IT equipment working in a suitable temperature for 24 hours a day, seven days a week 365 days a year. Air conditioners cooling computer rooms have to remove constant amounts of heat, whether the outside ambient temperature is high or low. Winter temperatures can reduce the efficiency of air conditioners that have to be designed to cope with the maximum heat removal in the maximum summer temperatures.
Over-condensing in lower ambients can cause rapid compressor cycling, problems with oil distribution around the refrigeration system and, in some cases, icing-up of the indoor unit leading to reduced capacity, shortened compressor life and higher electricity charges.
The Extreme range of low ambient controllers from EDC will compensate for these lower ambient temperatures and restore normal operating conditions to the refrigeration system completely automatically.
The control unit is mounted inside the outdoor unit with its sensor fitted to the condenser coil; there is no interference with the refrigeration circuit and no intrusion into the refrigerant itself. By measuring the condensing temperature and adjusting the speed of the condenser fan to maintain constant heat removal even in low ambient temperatures, this unit keeps the pressures within the system at their design levels.
Bearing in mind that ac systems in even the smallest of computer rooms have to work just as efficiently in the winter as in the summer, it is important that service and maintenance plans are put in place as soon as the system is commissioned to avoid air conditioning failure.
Another way of protecting against failure is to install a temperature alarm, like EDC’s FPAD-1000. Mounted on the wall, inside or outside the room, the display provides reassurance that the room is at the correct temperature. But setting the alarm temperature level at 3°C above the ‘normal’ temperature provides the ultimate security. In the event of a rise in room temperature to this alarm level, the module has a flashing red light and after a short, adjustable time delay, an audible alarm sounder will warn of the abnormally high temperature.
At the same time, its internal alarm relay changes over. And this can be connected into a BMS (or other alarm system, including auto-dial equipment) to alert an engineer to the fault.
EDC also produces a matching remote alarm module which can be connected to the master FPAD-1000. This can be fitted in an occupied office nearby, or perhaps to a distant security office, to give immediate warning of a problem in the distant room up to 500m.
Both these protection modules have independent internal battery back-up systems to keep their functions operating through interruptions in the mains power supply, and if there is a power supply fault, the alarm relays will immediately provide a warning signal. At the same time, the internal battery back-up system continues to power the modules and their temperature-monitoring function. So if the power supply fault also causes the air conditioning to fail, early warning can be given of the potential rise in room temperature.
One of the computer manager’s worst nightmares is that of water, particularly leaks from the ac or in the under-floor cable ducts.
Another module from EDC, the KWA-1000, can also link into the protection system to warn of water leaks. Like its sister unit, the KWA-1000 provides protection against power failures, and will detect even small amounts of water on its detector plates, of which up to 20 can be strategically placed in the computer room.
To provide a protection system is an essential insurance, and the FPAD-1000 and KWA-1000 can give peace of mind that temperature faults can be detected at an early stage, and that water damage can be prevented. When combined with the remote alarm module, a system can be easily built to protect against the major faults that can cause computer room failure.
Small computer room air conditioning can be very worthwhile for the contractor/installer but as the system has to work all day, every day, it is critical that equipment and system design take this into consideration and that service and maintenance is carried out regularly.
Providing your customer with peace of mind as far as his invaluable computer data is concerned is paramount.
EDC International
0044 (0) 1189842040