Abstract: A refrigeration monitor system for monitoring an unattended freezer installation having a number of freezer compartments containing perishable products. The system comprises a network of temperature sensors located in the freezer compartments and connected to a common control which is connected to one or more telephone lines. The common control is capable of dialling in sequence anyone of a group of selected alarm numbers. The person answering the alarm call receives a recorded message and must return a preselected answer code that is received by the system, and which stops the system from sending more alarm calls. The system continues to dial alarm numbers until it receives a satisfactory answer code. As a further safety measure the system, upon initiating an alarm, sets an alarm status indicator that must be manually reset within a preset time by the person attending to the freezer installation in response to the alarm, or else a new alarm sequence is automatically initiated.