Abstract: Apportioning energy costs among units by sensing a heat exchange for at least one heat exchanger in each unit. In response to this sensing, a value corresponding to an amount of heat provided by the heat exchanger is determined for each unit. Each value is transmitted to a central location, and they are processed to apportion energy cost for each unit as a function of the respective value. Total values for each heat exchanger can be summed to provide a summation value corresponding to a total amount of heat provided to the unit over time, and energy costs can be apportioned as a function of this summation value for each unit. A probe that includes a probe body and an electrical heat sensing element mounted in the probe body. A tamper detecting mechanism responds to forces applied to the probe and interacts with a conductive lead of the probe to provide an electrical tampering indication.

Abstract: A bi-directional data transmission and control system utilizing a central processing unit and a multiplicity of remote subscribers. Each subscriber is provided with a terminal coupled with the central processing unit by a suitable medium such as a CATV channel. Each terminal is provided with a demarcation plane separating common circuitry from a number of specialty modules and a common bus therebetween for circuitry simplification, application expandability and individual tailoring. The data transmission scheme efficiently utilizes the frequency spectrum and enhances polling frequency by permitting selective polling of any given specialty module or subscriber at any given time and by permitting simultaneous polling of every subscriber for service calls, thereafter locating the caller with minimal polling. Data transmission protocol is expandable or contractable for each terminal independently of others and permits data transmission between any two points in the system.