A remote monitoring and alerting system includes one or more remote terminal units and a central system, with both the central system and each remote terminal unit adapted to send and receive data across a communications network. Each remote terminal unit includes a processor and wireless transmitter in a compact arrangement that allows the unit to be placed conveniently in a housing associated with some remote device to be monitored. The central system includes a data collection and manipulation controller for receiving, processing, and storing data received from each remote terminal unit across the communications network. Both a user messaging controller and a user interface controller are also included in the central system. The user messaging controller transmits user messages through a suitable interface to one or more user designated devices in response to a remote terminal unit message received from the remote terminal unit. The user interface controller provides a user interface between a user of the remote monitoring and alerting system and the central system.