Abstract: A control device for a hot water heating system which has a boiler, water pump and motor control mixing valve. The control device is responsive to the outside temperature for turning the pump on and off when the outside temperature drops below or exceeds a predetermined pump set point. A set of water reset ratios is defined and a range of offset adjustments are provided for each ratio and are selected for controlling the heat level within the system. The desired water temperature is periodically determined for the output of the mixing valve for the selected water reset ratio and offset and is receptive of the actual water temperature for comparing the actual water temperature to the desired water temperature. The mixing valve is then controlled by opening or closing same to make the actual water temperature correspond to the desired or computed water temperature.

Abstract: A heating system control device is responsive to the drop in outside temperature to below a predetermined weatherhead set point for turning on a heating system to be controlled. Upon the establishment of the heat in the heating system, a defined heating cycle is carried out consisting of a heat-on portion and a heat-off portion having a duty cycle dependent on the outside temperature. The heating cycle does not start until there is an establishment of heat in the heating system. The start of consecutive heating cycles is delayed in response to a check for heat loss in the system. When heat is established and the set point has not been reached, as noted by the means for determining the establishment of heat in the heating system, the next cycle will be delayed to save energy.