Emerson ITR Manuel D’Utilisation

For sensitive electronics, environmental control is more than simple cooling. “Comfort” air condition-

ing systems are designed for the comfort of people and simply cannot provide the kind of environment 

required by high performance computer or communication equipment.

The high density heat load in a computer room or other similar application is beyond the capacity of 

ordinary air conditioning systems.
Sensitive electronics are best maintained in a stable environment of 72°F ±2°F (22.2°C ±1°C). Because 

computers and communications equipment generate large quantities of heat in small areas, six to 10 

times the heat density of normal office space, the air conditioning system must have more than just 

enough cooling capacity. It must have the precision to react quickly to a drastic change in heat load 

and prevent wide temperature fluctuations—something a large building system cannot do.

The electronic equipment must be protected from both internal condensation and static electricity dis-

charges.
Maintaining the correct humidity level in the room is just as important as maintaining proper tem-

perature. When humidity is too high, condensation may form inside electronic equipment and damage 

it. If humidity is too low, static electricity could disrupt operation or even shut down the electronic 

system. An ordinary building system cannot normally control the environment within these boundar-

ies.

Computers and other sensitive electronics require greater air volumes than ordinary air conditioning 

can provide. Typical comfort systems are designed to provide between 300 and 400 CFM (cubic feet 

per minute), (500–700 CMH) per ton of cooling. Computer systems require between 500 and 600 CFM 

(850–1020 CMH) per ton. The high density heat load in a relatively small space requires more 

changes of air than a less dense “comfort” application.
While a normal office space requires only two air changes per hour, a room filled with electronic 

equipment requires up to 30 changes per hour. Without proper air volume, hot spots and temperature 

fluctuations could develop within the room. Also, greater air volumes provide the higher sensible heat 

ratios required by electronic computer equipment.

A clean environment of properly filtered air is essential. Build-up of dust and fibers attracted by oper-

ating electronics can cause faults and impair the operation of electromechanical devices, such as 

switches and disk drives.
In short, today’s electronics need the same precision environmental control that mainframe comput-

ers need. The difference is that instead of one large computer room there are several small, often 

crowded rooms, widely dispersed throughout a building, plant or campus. Conditions and require-

ments can vary widely.

Comfort conditioning systems cannot be relied upon 24 hours per day 365 days per year. They are typ-

ically designed to operate 10 hours per day, from spring to autumn. Many “comfort” systems have no 

provision for winter operation. A precision environmental control system is designed for operation at 

temperatures down to -30°F (-34.4°C).

Standard 60 Hz units are CSA (NRTL-C) certified. NRTL-C meets both U.S. and 

Canadian government safety requirements, providing fast, problem-free inspec-

tion and building code approvals. The units are also MEA listed for New York 

City applications.