The development of high reliability modular cooling system in British Telecom

British Telecom cooling system are now based on highly standardized, modular cooling units which use fresh air as the principal cooling medium and incorporate the refrigeration plant. A ventilated ceiling is normally used to deliver air to the room but a downflow unit for use with raised modular floors is also available. More recently a unit incorporating a dry cooler has been introduced. For small rural exchanges, total fresh air units are used. The units are all sited in the exchange room, and each requires only a single hole through an outside wall. The control system is standardized and has recently been redesigned to incorporate remote diagnostic facilities. The approach adopted has been highly successful. Over 3000 units are now in use, and there have been no instances of service failure due to loss of environmental control