Abstract: A conventional hot water heating system generally of the type for heating water in multiple units of hotels, motels and the like and using any heating medium has a processor and control assembly operationally connected to at least a heating control means, a water temperature sensing means and a water flow sensing means thereof. The processor and control assembly divides the time into exact time periods, say one-half hour, and the time periods are grouped into a group of consecutive time periods, say a week. Taking any individual time period, a directly preceding time period is checked with the same time period in the preceding group of time periods and if the two match within a given degree, the assembly adopts all of its settings from its particular time period a week ago. In addition, the assembly exactly records the various settings throughout that particular time period and when that time period comes up again one week from now, those are the new settings by the processor and control assembly to be used.

Abstract: Apparatus and method for controlling a hot water heater to heat water during off peak load hours to a desired temperature by the end of a predetermined period of time. The heating is in partial increments, the water being heated a partial amount in each of a plurality of predetermined time segments with a view to reaching the desired temperature at the end of the predetermined time period. The water is heated by adjusting the heater at each segment to its maximum power or a portion thereof. The method includes the steps of computing the heater power required for the next time segment, setting the heater power accordingly, waiting until the end of the time segment, determining the new temperature of the water, and repeating the steps until the end of the time period.