Abstract: The present invention is a method and apparatus for changing fuels used in a heating system without substantially recycling the heating system where a main flame burns fuel supplied to the heating system. A fuel changeover signal is received from a fuel selector. Flow of a first fuel to the heating system is regulated in response to the fuel changeover signal to achieve a low fire state in the heating system. A pilot flame is established in the heating system and flow of the first fuel is shut off. A fuel indicator signal is received from the fuel selector indicating a desired fuel. The main flame in the heating system which is burning the first fuel is extinguished. The pilot flame is monitored for stability and the main flame is re-established in the heating system burning the desired fuel in response to the fuel indicator signal.

Abstract: A method and apparatus control firing rate in a heating system to compensate for thermal mass characteristics of the heating system. The thermal mass characteristics of the heating system are derived from heating system identification information. A weighted control response factor is selected which is representative of load characteristics of a load type affecting firing rate control and which is representative of desired control tightness. The firing rate is varied, based on the weighted control response factor and the thermal characteristics, to match the heating system, the load type being controlled and the desired control tightness for optimum control.

Abstract: A method and apparatus monitor fuel pressure in a heating system where a controller controls actuation of fuel valves. A fuel pressure limit signal is provided to the controller for determining if the fuel pressure crosses predetermined thresholds. In order to avoid nuisance shut-downs, the fuel pressure limit signal is ignored by the controller for a predetermined time interval after the controller has actuated a fuel valve.

Abstract: An electric boiler includes a conductivity control having a controller responsive to both steam pressure and electrode current. The controller is operative to open a boiler feed water discharge valve when either the steam pressure or electrode current falls below predetermined values to discharge water from the boiler for a predetermined time interval after which the controller closes the discharge valve and opens a feed water valve to initiate the delivery of feed water to the boiler chamber. When the pressure or current sensor senses the elevation of steam pressure or electrode current to second preselected levels the controller closes the feed water valve. In addition, if the sensors determine that the steam pressure or electrode current have risen to third preselective levels, a transfer valve is opened to transfer boiler water to a storage tank until the pressure or current level falls to fourth preselected levels.