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 valve control circuit is disclosed for operating a modulating valve which can be operated between a completely open and a completely closed position. The modulating valve control circuit includes a microcontroller which receives an input signal from an external temperature controller. The microcontroller monitors and controls the position of the modulating valve by first determining the number of rotations of the bi-directional driving motor required to move the valve from a completely open to a completely closed position. After determining the number of rotations for a complete valve stroke, the microcontroller positions the valve stem in the correct position according to the input setpoint as compared to an input range. The microcontroller positions the valve stem in direct relation to the proportion of the input setpoint signal with respect to the range desired.

Abstract: A solenoid control circuit is disclosed for providing the initial pull-in power to a magnetically-held solenoid and thereafter providing a release-pulse upon power loss to the circuit to release the solenoid. The solenoid control circuit has an AC input which is converted to a DC power supply. Power is supplied to an energy storage device after an initial time delay. After the time delay, the magnetic solenoid is tripped to its hold-in position. After being tripped, the magnetic solenoid is held in its hold-in position by the magnetic properties of the solenoid. Upon power interruption to the circuit, the solenoid is held in its tripped position for a desired period of time. After the time delay has expired, the energy storage device is discharged in an opposite direction through the magnetic solenoid, such that the magnetic solenoid is returned to its extended position.