Abstract: An apparatus for controlling the speed of a combustion blower motor includes first means for generating an output signal representative of a differential pressure. A second means provides a second signal representative of a desired airflow output of the blower and a summation circuit receives the first signal and the second signal and generates a command signal in response thereto. A power output circuit receives the command signal and responsively provides a regulated level of power to the motor for controlling the speed thereof. The first means may be embodied as a diaphragm-type differential pressure transmitter while the second means may be embodied as an adjustable voltage source or as a source which provides an output signal representative of a temperature.

Abstract: A differential pressure control apparatus includes a switch responsive to a pneumatic differential pressure for signaling the actuation of a blower motor. A signal generating section is provided and controls the speed of a blower for regulating the differential pressure. This section includes first means for sensing a projected light beam and second means for modulating the light beam. The first means and the second means are positionably displaceable one to the other in response to the magnitude of the differential pressure. Two preferred embodiments are disclosed.

Abstract: A mechanical draft controller integrated in the draft hood of a furnace and coupled to a flue damper is responsive to the draft in the flue for controlling exhaust stack heat loss and eliminating heated room air loss via the draft hood under normal operating conditions. The pressure-sensitive controller is variably positioned as a face damper on a surface of the draft hood and is coupled to the flue damper by means of mechanical linkage. Increasing pressure in the draft hood caused by a reduction in the draft value due to partial flue blockage, large down draft, etc., displaces the pivoted controller resulting in a corresponding opening of the flue damper to re-establish the desired draft value. Similarly, excessive draft causes the displacement of the controller in an opposite direction resulting in flue damper displacement so as to reduce the draft value and exhaust stack heat loss.

Abstract: A heater vent having a temperature responsive damper such as a bimetallic element is disclosed. A shroud-like structure is positioned to cooperate with the temperature responsive element to close the vent at an elevated temperature and thereby reduce loss of residual heat while permitting the combustion gases to be completely purged from the firebox. For safety, movement of the temperature responsive element is uninhibited in all positions with complete vent closure occurring at ambient temperature and with the damper open during heater burner operation.

Abstract: The system includes a damper plate equipped with a draft controller or sensing switch and a motor for positioning the damper plate to control the furnace draft. Upon generation of a call-for-heat signal, an initialization signal drives the damper off its closed position. From then on, draft must be sensed by the draft controller switch to complete the cycle to open the damper plate. When the damper plate is fully opened, a fuel and ignition control circuit is energized to supply fuel to the furnace, and an electronic timer is energized to generate a signal which establishes a trial-for-draft period. When the fuel is ignited, the draft will increase and energize the motor to move the damper plate off the fully open position during the trial-for-draft period, and thereafter, the position of the damper plate is controlled by the draft controller switch to achieve a proper draft within design range.

Abstract: A pilot assembly includes a base having a cylindrical side wall which holds an electrode subassembly and glass preforms in place for fusing the glass to secure the electrode subassembly to the base. Prior to fusing, a spark electrode is assembled by inserting it into a metal clip receptacle held in a ceramic insulator body forming a part of the electrode subassembly. A pilot tip and orifice subassembly are secured to the base. Fusion of the glass and brazing of the metal including the high tension clip to bring it to spring temper for connection to a plugged wire are accomplished in a single step of heating. The pilot tip includes a locator member which holds the spark electrode in place during fusing and establishes the spark gap. It is removed after fusing.

Abstract: An electronic thermostat includes digital electronic apparatus for simulating heat anticipation so that in operation, the temperature of the room being heated or cooled does not exhibit excessive overshoot. A sensor generates a signal representative of temperature in the room. In a preferred embodiment, the system compares the temperature signal with a composite set point signal. The composite set point signal is generated by a data processor to effect the following system characteristics: (1) when the temperature signal remains constant and is equal to the set point, the system can cycle approximately six times an hour with a fifty percent duty cycle; (2) a relatively small change in temperature or set point will modify the duty cycle substantially; and (3) if the temperature and set point signals differ by more than a predetermined amount, the system will lock on or off, depending on which is greater.

Abstract: The illustrated embodiment is electronic. It includes circuitry for simulating heat anticipation so that in operation, the temperature of the room being heated or cooled does not exhibit excessive overshoot. A signal is generated representative of a desired set point, and another signal is generated representative of room temperature. An output signal, derived from a comparison circuit, is either ON or OFF. An integrator is reset each time the output signal is switched and generates a ramp voltage of increasing magnitude and having a polarity tending to reverse the state of the comparison circuit. The comparison circuit generates an ON signal when the set point signal is greater than the combined temperature and ramp signals; and it generates an OFF signal when the set point signal is less than the combined signals. The comparison circuit latches up once it has switched to avoid hunting or chatter.

Abstract: A furnace ignition and draft control system includes a damper plate movable under control between a closed and an open position. When a call for heat signal is generated, a holding relay is actuated to energize a damper motor to open the damper provided the damper plate was closed when the signal was generated, otherwise the system will not operate. After the damper is run to the full open position and this is proved, a fuel control circuit is actuated to supply fuel to the furnace, and a trial-for-draft period is initiated. A draft controller energizes the damper motor to open the damper if draft is less than a first predetermined value and to close the damper if draft is greater than a second predetermined value. The predetermined draft values define a desired draft range in which the damper is not operated.

Abstract: A control system for use with gas-fired appliance installations, such as a furnace, includes a switch responsive to normal draft levels in the vent stack. At the start of a heating cycle, and in the absence of draft, the switch permits a pre-draft enabling circuit to tentatively enable the furnace controller for a predetermined time. The controller opens a stack damper plate and actuates the ignition system and gas valves of the furnace. If draft is not established within the predetermined time, the pre-draft enabling circuit times out and the gas is shut off. If normal draft is sensed within the predetermined time, the draft responsive switch permits the furnace controller to be operated as long as the thermostat calls for heat. If, for any reason, draft subsequently stops, the control system re-cycles itself; and if draft is not re-established before the pre-draft enabling circuit times out, the system deactivates the furnace controller.

Abstract: An humidistat has an element movable in response to ambient relative humidity operatively connected to a core of a linearly variable differential transformer for moving the core. The core is supported within a body portion of the transformer for minimal friction of movement relative to the body portion. The body portion has a primary winding and two secondary windings. An oscillator excites the primary winding to provide output signals from the secondary windings proportioned to movement of the core in the body portion and, therefore, indicative of the relative humidity sensed by the element.

Abstract: A fuze setting device utilizes a plurality of detented, rotatable, magnet sitioning time setting rings and an encoding disc for controlling the amount of electrical pulses that a timing oscillator is required to subsequently generate to fill an "and" gate controlled multi-stage counter. The counter after being filled generates a fuze initiating signal. A setback detented electromagnetic pulse generating despin operated sensor assembly is used in combination with the oscillator to generate electrical pulses for partially filling the counters in accordance with the relative angular positioning between the magnetic source setting rings and the pole pieces of electrical coils which generate a stop pulse to regulate the number of pulses necessary to fill the counters.