Abstract: A control unit and a related method of operation for controlling the temperature of the water circulated in the radiant loop of a hydronic heating system. The control unit includes temperature setting dials that can be used to adjusts the reset curve used to determine the desired secondary, radiant loop water temperature. The control unit generates a linear reset curve between two setpoints such that the control unit can calculate a desired secondary loop water temperature based on the reset curve and the present outdoor air temperature. The control unit monitors the temperature of the water returning to the boiler from both the primary loop and the secondary, radiant loop. The control unit monitors the return water temperature over a first interval and, based on the rate of change in the return water temperature, calculates a predicted return water temperature at a second interval in the future.

Abstract: A hydronic heating system including a single self-contained hydronic control unit. The hydronic control unit allows for zoned heating operation in which a series of individual room thermostats and zone valves control the flow of heated water into each of the heating zones. The hydronic control unit operates an oil or gas fired boiler to maintain boiler water temperature at a selected value. The hydronic control unit includes a priority terminal which can be connected to a priority heating zone, such as an indirect fired water heater. Upon receiving a demand for heat from the priority heating zone, the hydronic control unit diverts the flow of heated water from the boiler to the priority zone exclusively. The hydronic control unit further includes a terminal for connection of an outdoor air sensor. In cooperation with the outdoor air sensor, the hydronic control unit can operate in a boiler reset operating mode such that the boiler temperature is related to the outside air temperature.

Abstract: A relay circuit for energizing a load in response to a control device and method of testing the relay circuit, in which a switch is provided for selectively disconnecting the control device from the relay circuit and activating a relay switch such that the load is energized when in a test mode and reconnecting the control device when in an operational mode. By disconnecting the control device in the test mode, the control device may be electrically isolated from the relay circuit thereby protecting the control device from damage due to backfeeding.

Abstract: A thermostat includes a printed circuit board capable of issuing temperature control signals, a wall mountable backplate holding the printed circuit board, signal transfer wire access openings allowing passage of signal transfer wires from a wall through the backplate to the printed circuit board, screw holes in the backplate for attaching the backplate to the wall, and snap clips capable of holding the printed circuit board in a plurality of orientations, the snap clips selectively holding the circuit board in one of the plurality of locations and selectively releasing the circuit board upon the application of force.

Abstract: An electrical control circuit is disclosed for controlling the operation of a pilotless gas system including an igniter and a gas supply valve, wherein the gas supply valve is initially opened a predetermined time after the igniter is activated, and the igniter is subsequently deactivated a predetermined time after the gas supply valve is opened. Specifically, a control first signal is produced to activate the appliance, which control first signal is delivered to a first logic circuit for activating the igniter, and to a first delay circuit which produces a second signal delayed from the first signal by a first predetermined time period. The second signal is delivered to a gas supply valve control circuit to open the supply valve, whereupon a detector produces a third signal in response to opening of the valve.

Abstract: A flame detection and proof device utilizing NAND logic implemented by MNOS devices which provides safe control of gas systems and appliances. Improved control is achieved by using a flame probe for providing signals indicative of flame and no-flame conditions connected to circuit means which includes at least one delay circuit for producing a first output signal during a set time period for ignition and also during indication of a flame condition and a second output signal after the set time period and during an indication of no-flame condition. A relay is responsive to the output of the circuit means to be activated during the first output signal and to be deactivated during the second output signal.