Abstract: A power regulating system make it possible to switch on a plurality of power stages with different air flow rates and different fuel flow rates on the burner of the heater. In addition, noise level is optimized, since the blower that maintains the air flow rate turns with a constant output and only the fuel flow rate is modified to regulate the heating power.

Abstract: In a fluid heating apparatus having a fluid tank, a combustion chamber communicating with the fluid tank for heat exchange, and a combustible fluid delivery system coupled to the combustion chamber, a plurality of valves are individually configured in either an off-state or an on-state for delivering combustible fluid to the combustion chamber. Depending on the configuration of the multiple valves, the rate at which combustible fluid is supplied to the combustion chamber may be varied in response to a heat demand signal. Individual valve signals are generated for each of the multiple valves in response to the heat demand signal to place the multiple valves in a configuration to supply combustible fluid at predetermined rates. The demand signal is calculated in response to reading temperature at an inlet temperature probe and an outlet temperature probe, wherein the outlet temperature probe is located nearer a fluid outlet from the fluid tank than is the inlet temperature probe.

Abstract: A control device for energizing and de-energizing temperature changing devices having a primary control unit and a secondary control unit is provided. The primary control unit includes means for sensing an external temperature and generating a signal (Ps) having a value proportional to the external temperature, means for generating a set point signal (Psp), representing one end of a predetermined primary temperature range, and means for generating a differential signal (Pd), representing the difference between signal Psp and the other end of the predetermined primary temperature range are included. Additionally, the primary unit includes a primary switch for connecting power to at least one temperature changing device which is opened and closed in response to combinations of signals Ps, Psp and Pd.

Abstract: A multiple-boiler heating system is disclosed in which each boiler or stage is provided with an adjustable firing level of modulation at which the boiler is turned on and an adjustable threshold level of modulation (the MOD point), below which the next stage is disabled from being turned on. A control device for the heating system continuously compares temperature in the area being heated to the set point for the system and determines the total change in system output level ("DUTYCHANGE") which would be required to produce a specified temperature within a predetermined time. Should DUTYCHANGE be negative, it is similarly distributed among the stages which are turned on. However, the reduction in modulation level proceeds backwards from the last stage which was turned on. When the last stage reaches its firing point, it is not turned off until the previous stage drops below its MOD point. The lead stage is turned off as soon as it reaches its firing point.

Abstract: The present invention involves a two stage furnace and a method of warming its heat exchanger. The furnace includes a gas valve with low and high combustion settings, and inducer and circulator fans with low and high speed settings. When a call for heat is present, the inducer fan and gas valve operate at high. After a heat on delay period, the circulator fan operates at low speed to provide an initial warm stream of air from the furnace.

Abstract: A two-stage gas furnace control system automatically shifts into a high fire only mode if, in two consecutive low fire heating cycles a limit switch is tripped to indicate that a gas valve is stuck in a high fire condition. In this way, continued operation is allowed to proceed in a safe manner. Provision is also made to lock out the system from further operation if, while in the high fire only mode, the limit switch is tripped in a predetermined consecutive number of cycles or if, while in a preemptive low fire only mode, the limit switch is tripped.

Abstract: An HVAC system for a plurality of zones comprising an air handling unit including a blower, a plurality of heating stages and a plurality of cooling stages. The air handling unit is connected via ducts to each of the zones, each zone having an air outlet provided with a two-position damper which is either open or closed and a thermostat for providing an input signal to a microprocessor. The microprocessor has outputs for activating motors to move the dampers and outputs for activating the heating and cooling stages. The system includes an automatic mode of operation in which the microprocessor controls the number of stages of heating or cooling which are energized in dependence on the difference between the number of zone therostats calling for heating and the number of zone thermostats calling for cooling.

Abstract: A gas valve for controlling the flow of a combustible, gaseous fuel to a burner employs a modular construction and is configurable to be fast or slow opening, to be step opening or to provide two firing rates in accordance with external signals applied thereto.

Abstract: A humidity control apparatus for controlling the humidity level of air within a given area. The apparatus includes a plurality of control valves connected in fluid flow communication to a fluid supply source for injecting water into the air within the area for controlling the humidity level within the area. A controller outputs electrical signals controlling the activation of the fluid flow control valves based on temperatures and sensor inputs within the area input to the controller along the with a multi-position switch which controls the present humidity set point within the area as well as the delay between activation of various numbers of the control valves in sequence with a predescribed time delay.

Abstract: The present invention relates to a method and to apparatus for regulating a heating installation in a premises comprising a plurality of heating generators. The apparatus comprises temperature probes (10, 20, 140) which are sensitive to the outside temperature, to the inside temperature, and to the departure temperature of the heating fluid leaving the heating generators. The apparatus further includes means (50, 60, 70, 80 and 100) for determining a reference temperature on the basis of a set temperature (Tc) as indicated by a setting unit (30). A proportional-integral regulator (120), sensitive to the difference between the reference temperature and the departure temperature of the fluid, generates a signal which is applied to threshold detectors which detect the passage of said signal through successive predetermined thresholds, thereby generating successive signals for bringing into service the corresponding heating generator.

Abstract: A boiler control utilizing a pressure sensor is provided that operates the system in the low fire mode if the load is light, and can be satisfied in that mode. If the low fire operation is inadequate to hold the load and the pressure drops, the boiler is then operated in a modulating mode which includes a high fire limit. This is accomplished by sensing the variation of a pressure responsive means and by providing a burner control system that monitors that pressure responsive means.

Abstract: A boiler control utilizing a pressure sensor is provided that operates the system in the low fire mode if the load is light and can be satisfied in that mode. If the low fire operation is inadequate to hold the load, and the pressure drops, the boiler is then operated in a modulating mode which includes a high fire limit.

Abstract: Apparatus and a method for controlling the flow of a fluid to a fluid-actuated system. The system is controlled by a sensor which senses a variable characteristic of the system, such as the air temperature. The apparatus includes a pair of solenoid valves, one valve being set to deliver a first volume of fluid per unit time and the other valve being set to deliver a second volume of fluid per unit time. The solenoid coil of one of the valves responds to the actuation and de-actuation of the sensor. The second valve has a solenoid coil controlled by a pair of switches. One of the switches is responsive to a first timing signal and the second switch is responsive to a second timing signal. One of the switches allows the second valve to be open for a first time interval during which the first valve is open; thereafter, the second valve is closed.

Abstract: A space heater, designed to maintain the temperature of a room between a lower limit T.sub.m and an upper limit T.sub.M, is controlled by a system including a sawtooth-wave generator working by way of a clipping stage into a differential amplifier also receiving a monitoring signal representing the difference between an output voltage of a temperature sensor and a reference voltage. The differential amplifier emits a train of command pulses of temperature-dependent duration which temporarily reduce the mean power of the heater to a fraction of its maximum value, as by periodically interrupting its fuel supply when that heater comprises a gas burner. The heater is cut off for an extended period when the upper range limit T.sub.M is exceeded and is then restarted when the temperature falls beneath the lower limit T.sub.m. In the case of a gas burner of the catalytic type, the cut-in is accompanied by a supply of additional gas to the burner for a limited time.

Abstract: A circulating fluid that is heated by a number of gas-fired burner assemblies is used to heat a space either through a hot water system or a forced air heating system. Each burner assembly includes a housing with a heat exchanger mounted therein and a gas burner for heating the fluid which flows through the heat exchanger. The heat exchangers are connected in parallel in a closed loop forced circulation system. A microprocessor based thermostat control compares the temperature in the space heated by the air with a reference temperature. Dependent upon the magnitude of the difference between the temperatures, one or more of the burner assemblies are energized. The burner assemblies are sized such that during most of the heating season only a fraction of the burner assemblies are used.

Abstract: A control system for multiple burners or heaters in an afterburner section of a metal scrap dryer is provided. The control system provides for cascade and sequential control including selective and sequential ignition as well as selective and sequential deenergization of the burners or heaters.

Abstract: A fluid-flow control valve arrangement comprising valve means operable in different conditions including variable-flow, constant-flow and zero-flow mode conditions depending upon predetermined ranges of a prescribed operational parameter, the valve arrangement being useful especially for the control of the flow of fuel in a heating device such as a gas-burning water heating device.

Abstract: A burner control system for a hot water boiler is responsive to both outlet water temperature and return water temperature to provide a relatively constant outlet water temperature regardless of variations in heat output requirements. A first thermistor responsive to return water temperature is effective to provide on-off control of gas flow to the burner. A second thermistor responsive to outlet water temperature is effective to vary the rate of gas flow to the burner so as to maintain a predetermined outlet water temperature. A timing circuit is effective each time the burner is turned on to delay a high rate of gas flow to the burner.