Abstract: In a forced air heating and cooling system including a blower fan for circulating air in an air ambient use-space, a timer circuit and a power output control circuit for augmenting control and for regulating operation of the blower fan. The timer and associated circuitry functions to activate the blower fan for finite limited periods of operation at each end of each heating and cooling cycle and at time-spaced intervals when neither heating nor cooling is called for in the controlled use-space. The timer device and supporting control circuitry are simply and readily incorporated into the conditioning system with a minimum of physical disruption of disturbance of leads and connections. Heating and cooling efficiencies are enhanced, comfort level is elevated, and objectionable temperature fluctuations are smoothed.

Abstract: A system which drives an indoor blower of a heating, ventilating, and/or air conditioning (HVAC) system in response to a system control signal. The system control signal has a BLOWER DEMAND state and a BLOWER END DEMAND state. The system comprises a motor having a stationary assembly and a rotatable assembly. The rotatable assembly is in magnetic coupling relation to the stationary assembly and in driving relation to the indoor blower. The system controls in response to the system control signal the rate of air flow of the HVAC system. The system operates at a first air flow rate in response to the BLOWER DEMAND state of the system control signal and operates at a second air flow rate greater than the first air flow rate when the BLOWER DEMAND state has been present for a first period of time. Alternately, the motor operates at a third air flow rate less than the first air flow rate for a second period of time in response to the BLOWER END DEMAND state of the system control signal.

Abstract: An electrical interlock ties a heat recover ventilator to circulation air blower operation of an associated forced-air furnace or air conditioning system. This ensure that the blower circulates supply and return air within the building or dwelling. An interlock relay has its coil energized by the heat recovery ventilator, and a normally open contact tied to the control of a blower of the forced-air system. The furnace or air conditioner and the ventilator are operated by separate controls located within the building's comfort space. When the ventilator is operated, the circulation blower runs continuously, but thermostat actuate of the furnace or air conditioner above will not operate the ventilator.

Abstract: A control system to control the operation of a furnace (10) having a fuel control unit (26) to supply fuel to a burner (24) includes a limit switch (48) within furnace (10) to detect an overheated condition. The limit switch (48) opens when a reference temperature is reached, shutting down the furnace (10). A logic unit (40) senses the state of the limit switch (48) and measures the shutdown period, and notes whether the shutdown period exceeds a predetermined interval. The logic unit (40) opens a lockout switch (38') that controls the fuel control unit (26) if the furnace is subject to a number of consecutive prolonged shutdowns that exceeds a predetermined limit.

Abstract: A humidification system for use with a heating unit to modify and maintain a predetermined level of humidity in an enclosed space using a pulse circuit for energizing a solenoid valve to allow pulsed output of water from a misting nozzle, The system operating the pulse circuit in a plurality of modes to provide humidity to the enclosed space,

Abstract: A two-stage furnace is operable at a high fire full rate mode and at a low fire partial rate mode when there is a call for high heat or low heat, respectively. In order for the furnace to be less prone to vent gas condensate formation when operating at low fire, and to permit the heat exchanger and vent pipe to reach equilibrium as soon as possible on both low fire and high fire, a shorter blower-on delay is provided for high fire and longer blower-on delay is provided on low fire.

Abstract: A thermostat is disclosed for controlling a heating system, particularly a forced hot-air furnace, so as to improve fuel efficiency and decrease peak fuel load. The thermostat controls the length of fuel-on cycles, so that the heat exchanger of the furnace is not saturated. A wide deadband (approximately 3.degree. F.) for the thermostat further aids in lessening fuel usage. Forced air operation continues for a secondary-delivery period immediately after the thermostat turns the furnace off, thereby extracting additional heat from the heat exchanger and ductwork, but the length of the secondary-delivery period is limited so that the heat exchanger does not cool off beyond a predetermined amount.

Abstract: A twinning controller or control circuit for use in an HVAC system is coupled between a system thermostat and at least two HVAC units coupled to a common duct. The HVAC units are heating, cooling or heating and cooling appliances such as heating furnaces, air conditioners, fans, other forced air systems, or other devices for heating and/or cooling an environment. The twinning controller is capable of operating in a single-stage mode (single mode) or a double-stage mode (dual mode). When operating in the double-stage mode, the twinning controller alternately operates the first HVAC unit and the second HVAC unit in order to extend the operating life of the HVAC units. The twinning controller includes a microcomputer which receives inputs from the system thermostat and provides outputs to the first and second HVAC units in order to efficiently control the temperature in an environment such as a living space.

Abstract: Furnace control for a forced air furnace utilized in multi-zone heating. The forced air furnace is made up of return ducts, a heat exchanger, warm air ducts, a circulation blower, and a burner. The forced air furnace receives heating requests from external control means wherein the furnace provides heat to a zone or multiple zones to be heated. The control for the furnace comprises a temperature sensor for sensing the temperature of the heat exchanger, a regulator for regulating the burner to hold the temperature at the heat exchanger constant during the on cycle of the furnace, a pressure sensor for measuring the pressure in the heat exchanger and a controller for controlling the circulation blower in order to maintain a constant pressure within the heat exchanger.

Abstract: An air heating apparatus such as a fan heater, a forced circulation type ware air heater, and, an air conditioner and heater, is operated while the amount of radiation is taken into consideration. Moreover, after a PMV value of the room to be heated is generated from the temperature, amount of radiation, etc. of the room to be heated, the burning amount, air flow and the like are controlled to make the PMV value 0.

Abstract: An HVAC controller including a first input; a second input; first means, responsive to a first signal received on the first input, for generating a first mode of operation; second means, responsive to a second signal received on the second input, for generating a second mode of operation; and third means, responsive to a third signal received substantially simultaneously on the first and second inputs, for generating a third mode of operation.

Abstract: Recreational vehicles and marine vessels provide for cabin environment heating by a thermostatically controlled furnace which is typically fueled by a portable supply of liquefied petroleum gas and electrically powered by an on board battery. The invention detects and corrects for the situation where the furnace does not light by cycling the thermostat to allow the furnace to relight. The device will allow for three trials before the thermostat is locked out in an off position to prevent the furnace from blowing cold air and draining the battery system. The device provides for centrally located indication of the current temperature and a resettable display of the furnace retrial and lockout condition status, as well as the gas pressure as delivered to the furnace.

Abstract: An adaptive furnace controller utilizing analog temperature sensing to maintain a constant preselected temperature in the heat exchanger during operation. The adaptive furnace control measuring heat exchanger temperature and regulating a controllable valve to adjust burner firing rate, thereby holding heat exchanger operating temperature constant. Further, creating constant on/off times based on the previous cycle on/off times of the furnace by regulating circulation blower speed. By increasing blower speeds to shorten "on" times or decreasing blower speeds to increase "on" times, and thereby achieving optimum cycle times.

Abstract: A thermostat is described for controlling a furnace for a hot air, hot water, or steam heating system which delivers heat to a heated space via a delivery system. The thermostat causes the system to conserve energy by limiting the "burn" or on-time cycle to a system-specific interval during which the heat exchanger of the furnace operates in its linear region. At the end of this interval (designated a "MAX.sub.-- ON" interval), the burn cycle is terminated, but delivery of heat to the heated space continues for a secondary-delivery interval during which the furnace's blower (or other delivery means) continues operation. The secondary-delivery interval ends when the residual heat has been extracted from the furnace and delivery system. The system then remains off until the next burn cycle begins. The duration of the off-time interval is such that heat input to the heated space and heat outflow to the ambient from the heated space are kept in equilibrium.

Abstract: The present invention is a furnace control system responsive to a circulator fan motor fault condition. Upon detection of the fault, the control determines a first time period which is required to activate the temperature limit switch of the furnace by continuous operation of the gas burner and a second time period which is required for the plenum to dissipate sufficient heat to deactivate the temperature limit switch. After determining the first and second time periods, the furnace control operates the burners for a fraction of the first time period and then allows the heat exchangers to cool for the second time period until the circulator fan motor fault is corrected or the demand for heat ceases.

Abstract: The present invention discloses a two stage furnace control. The control includes a gas valve, an ignitor, a low pressure switch, a high pressure switch and a control unit for enabling the inducer fan, the circulator fan, the ignitor, and the gas valve. The gas valve is coupled in series with the low pressure switch, the high pressure switch, and the power source whereby the low and high pressure switches directly control supply of electric power to the gas valve.

Abstract: A dynamic environmental control system for managing the environment in a super insulated tightly sealed home which has a heat recovery ventilator connected to a forced air heating system for ventilation. The system controls indoor temperature, humidity and fresh air levels as well as temperature gradients using a heat recovery ventilator, heater and an air ventilation fan. The system can initiate operation of the heat recovery ventilator to exchange moist and polluted inside air for drier fresher outside air to control both inside moisture and air pollutant levels. Air exchanges can be initiated by an internal system timer, manually by building occupants or by the system in response to humidity levels inside the home. The system will determine the moisture contents of inside and outside air and will only attempt to exchange air to lower inside humidity levels when the outside air contains less moisture than the inside air.

Abstract: A forced air heating system having a dedicated supply duct for delivering heated air to the heated portions of the building and having an open air return system which uses the rooms, hallways, door openings, etc. of the building for returning air back to the furnace for reheating and recirculating. The elimination of a dedicated return air duct significantly improves the distribution airflow volume and thereby the efficiency and comfort of the central heating and air conditioning. The system includes a flue draft controller which monitors the flue draft at all heating applicances, such as furnaces, hot water heaters, etc., and servos a damper in a single main flue serving all appliances to optimize the flue draft for all appliances. If the flue draft becomes inadequate in any appliance, the controller shuts down heating appliances, as well as all heating system circulation fans, power fans and building exhaust fans which can affect the flue draft.

Abstract: An electronic control for a warm air furnace blower including an input circuit for receiving a signal from a thermostat. The signal is delayed by a first adjustable time delay to operate a blower relay, which energizes the blower. When the input signal ceases, a second adjustable time delay serves to delay opening of the blower relay. A second input circuit for receiving an emergency signal operates the blower relay without delay, and the second time delay serves to delay opening of the blower relay after the emergency signal ceases.

Abstract: Apparatus for modifying the temperatures of upper and lower level building interiors including air delivery means, heat generating means and first and second temperature sensing means for sensing the temperatures of the upper and lower level interiors. Air is delivered from the upper level interior to the lower level interior when there is a first sensed temperature differential between the interiors and the air is heated when the sensed differential drops to a predetermined lesser magnitude.

Abstract: A gas burner control system includes an electrical resistance igniter, gas valve means, and a microcomputer and related circuitry. The microcomputer and related circuitry control energizing of the igniter in such a manner so that the igniter, after successive ignition attempts, will eventually, in response to a learning routine, be heated to a desired ignition temperature. The microcomputer and related circuitry also control operation of a circulator blower in response to burner flame and provide for numerous checks on the integrity of system components.

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 blower motor failure is detected by a sensor/switch that opens at a first preset temperature level and automatically resets for the next cycle. The occurrences of such openings per thermostat cycle are counted and when they reach a predetermined number, the microprocessor causes the system to lockout from further operation, thereby preventing the temperatures from reaching excessive levels. In order that the same system may be used in a horizontal furnace installation where the first sensor is less responsive because of its location, a second sensor, of the manually resettable type and having a preset temperature level for opening which is higher than said first temperature limit, is employed to thereby lockout the system.

Abstract: A furnace which normally operates from a residential AC power source is adapted to operate on auxiliary DC power by changing the normal control function to substantially prevent the furnace from operating in the high heat mode during periods of auxiliary power use. Relays can be used to automatically connect the emergency power and to effect the change of the control function.

Abstract: Electronic control system for a gas-fired/hot air furnace includes a primary control unit which controls the flow of fuel to the furnace. The furnace has heating and cooling space thermostats and a comfort fan to supply heated or cooled air to the space being monitored by the thermostats and an induced draft blower which supplies combustion air into the furnace for heating. A first switch and associated relay drive selectively energizes the comfort fan for low speed heating operation and a second relay switch and associated relay drive selectively energizes the comfort fan for high speed cooling operation. Actuation of the heating thermostat energizes a third switch and associated relay drive which energizes the induced draft blower. A high temperature thermostat located to sense excessive furnace temperatures is also connected to actuate the third relay to energize the induced draft blower in an excessive temperature condition.

Abstract: A microprocessor control determines, in the course of initiating a heating cycle, whether the blower is operating in the continuous mode, and if it is, the control prompts the blower to be turned off prior to the ignitor being turned on. In this way, the blower and ignitor are never on at the same time and the instantaneous total current draw is limited to thereby reduce the occurrence of burned out fuses or circuit breaker trips.

Abstract: A control system for a combined heating and cooling system connected to the control circuitry therefor, for energizing a fan or other fluid circulating device to circulate fluid and effect thermal transfer of energy therefrom to the spaces being heated in response to energization of the heating and cooling system, and for deenergizing said circulating means a selected time interval after deenergization of said heating and cooling system to effect extraction of thermal energy from the circulating fluid, said control system being operative in the absence of electrical energy or other malfunction to energize fluid circulating device.

Abstract: A control circuit for a forced-air heating system comprises a silicon diode that is positionable in thermally-conductive relationship with the interior space of a furnace plenum. A current source supplies current to the silicon diode, and the potential drop across the silicon diode is sensed. The operating speed of the blower is controlled in response to the voltage drop across the silicon diode in a manner such that when the temperature in the plenum is below a first level, the blower is not driven; when the temperature reaches the first level, the blower is driven at a first speed; and when the temperature reaches a second level, which is higher than the first level, the blower is driven at a second speed, which is higher than the first speed.

Abstract: A temperature conditioning system has a temperature conditioning apparatus such as a heating apparatus or cooling apparatus, an air treatment for cleaning apparatus and a fan for moving air through the temperature conditioning apparatus and air treatment apparatus to supply the conditioning air to a space in which the temperature is controlled by a space thermostat connected to control the heating and cooling apparatuses. The space thermostat has a switch connected through a fan cycler to provide for cycling the fan independent of the operation of the heating and/or cooling apparatus to periodically move air through the air treatment apparatus and throughout the space to insure that the air is periodically treated and moved throughout the space to prevent stagnation when there is no call for operation of the heating and/or cooling apparatus.

Abstract: A furnace having the capability of operating its blower continuously is provided with means for automatically shutting off the blower at the beginning of a heating cycle and for resuming the operation thereof only after a predetermined time has elapsed to allow the heat exchanger to heat up to a temperature that exceeds the dew point of the flue gas, to thereby reduce the occurrence of cold spot corrosion in the heat exchanger. Provision is also made, in a two speed blower system, for operating at a lower speed during continuous mode and heating cycle operation, and for operating at the higher speed during the cooling cycles.

Abstract: A self-correcting control system and method is provided for a furnace to correct certain operating conditions that exceed normal limits. Upon sensing insufficient air flow as a function of the pressure drop across the heat exchangers, the control system and method cause the inducer motor to increase in speed, thereby to increase the flow of combustion air. Similarly, upon sensing that the flow of air to be heated exceeds a predetermined temperature, the control system and method will increase the speed of the air blower to increase the flow rate of air to be heated through the furnace, thereby resulting in lowering the temperature of the air to be heated below the predetermined temperature. Upon sensing a gas flow leak through the gas regulator, the control system and method will recycle the gas regulator to properly seat a gas flow control valve therein. If none of the self-correcting features correct the particular occurring problem, the control system and method will shut down the furnace.

Abstract: A temperature sensitive duty cycling control switch is mounted to a forced air ductless gas or oil heater by a special mounting bracket. The bracket attaches to the front of the heater in the path of the heated airflow. The mounting device is basically a tapered conduit or duct which is held at a distance from the heater so that it does not unduly obstruct the airflow and is tapered to concentrate air generated by the heater onto a plate mounted in front of the duct. The duty cycling control switch is then mounted to this plate and responds to the temperature of the plate. This enables the cycling of the heater burner while the fan continues to operate.

Abstract: A device is disclosed which causes a fan of a heating and/or air conditioning system to continue to run until the temperature in the duct work of the system reaches a desired temperature, so as to remove all heated and/or cooled air from the system, however, the device is designed so as to not cause the fan to be actuated due to changes in the duct work temperature which are due to changes in outside temperature or causes other than the operation of the system. A sensor which is located in the duct work controls the operation of the fan in response to temperature changes only if the sensor control circuit is first energized by the operation of the system.

Abstract: A blower control circuit for a furnace includes a blower relay having normally-open contacts connected in the power circuit to the blower. Energization of the relay via a drive circuit serves to close the contacts and thereby operate the blower. Control of the drive circuit resulting in relay energization is effected by either a time-delay circuit which responds to a space thermostat or a safety sense circuit which responds to a high temperature limit thermostat.

Abstract: A boiler air flow controlling apparatus for feeding air in a desired air flow to a boiler by cooperation of a first fan for feeding air to the boiler with a second fan for sucking air from said boiler. The apparatus includes means for varying, when the number of poles of at least one of motors for the two fans is changed over, the opening of a damper located in an air course in order to restrict a variation of the inner pressure of the boiler upon such changing over to a value within an allowable range.

Abstract: Environmental heating/cooling systems are controlled by an interactive microprocessor and have continuous on-time and adaptive cycling modes wherein continuous on-time brings the temperature to a programmed set point and cycling precisely maintains that temperature rather than causing the temperature to oscillate between limits of a dead zone. Minimum pause and on-time intervals of the cycling mode are established in accordance with optimum thermal transfer efficiency and/or equipment limitations. The initial cycle pause interval is a function of the degree transition time (i.e., time required for system to change temperature one degree as measured during continuous on-time mode); the initial cycle on-time interval becomes the established minimum interval. Cycle intervals are modified as necessary to maintain the temperature at the set point with preference given to minimizing the cycle on-time interval.

Abstract: An emergency heat bypass arrangement for a furnace in which the normal controller path is supplemented by an alternate path through a relay subject to an emergency heat switch controlling the solenoid of the relay, and the relay includes additional contacts for keeping power on the solenoid even after the furnace high pressure switch changes contacts to provide heating when said controller has malfunctioned.

Abstract: A control system for heating and cooling devices is disclosed which increase the total running time for the heating and cooling devices as the ambient temperature sensed deviates from the set-point temperature. Five states of ON-time modulation of 2, 5, 10, 15 and 20 minutes are preferred in response to this deviation. Constant periods of OFF-time of 2 or 5 minutes occur after each period of ON-time. Within a small deviation of the ambient temperature around the set-point temperature no conditioning equipment is operated. Beyond a large deviation, the respective heating or cooling equipment is operated continuously. A manual override is disclosed, and the system is manually switched from a heating to a cooling mode. A fan control line switches on whenever a heating or cooling device is actuated and the control system can be used with a heat pump.

Abstract: A furnace fan control for providing operation of the fan after the termination of the furnace burner in an adaptive manner to provide for longer fan operations after the burner turns OFF, as the burner ON time increases.

Abstract: The present invention provides a heating device including a combustion chamber for burning a selected fuel where the combustion chamber is at least partially surrounded by air heating plenums through which ambient air is forced. A portion of the air supplied to the plenum chamber is supplied to the combustion chamber to support combustion of the fuel and the device further includes a combustion air flow control device operated by a bi-metallic temperature sensing element located in an outlet of the heated air stream to attenuate flow of combustion air to the combustion chamber in response to change in the temperature of the heated air.

Abstract: A method of increasing the efficiency of a hot air furnace by measuring the temperature differential across the heated air inlet and outlet plenums which occurs during normal operation of the furnace to raise the room temperature from its turn on point to its turn off point. The plenum temperature differential is then used to time cycle the burner.

Abstract: A dual-rate fuel flow control system for the gaseous or liquid fuel supplied to the burner of a space heater, comprising a valve controllable to supply full fuel flow to the burner at the start of a heating cycle to deliver full heat to the heat exchanger chamber in which circulates the heat transfer fluid, and controllable to supply reduced fuel flow to the burner simultaneously with starting the circulating of the heat transfer fluid from the heat exchanger to the space to be heated.

Abstract: Control circuits are provided for a heat exchange unit including environment responsive means placed in the general area of the heat exchange unit's heat exchanger or of the associated heat distribution network or return system. The environment responsive means is connected in series between the heat exchange unit's main control switch, such as a thermostat, and the fuel valve which controls the flow of fuel to the unit's burner. The environment responsive means may be either independent of, or connected in parallel with a heat circulator if any, associated with the unit's heat exchanger. The control circuits of the present invention control the action of the heat exchange units fuel valve to create an intermittent heating flame in response to environmental changes at the heat exchanger, heat distribution network or return system during each heat demand cycle.

Abstract: A control circuit for a solid fuel furnace which includes a combustion chamber, means for delivering solid fuel to the combustion chamber, and means for delivering combustion air to the combustion chamber, wherein the control circuit includes thermo-sensitive means responsive to a demand temperature and to a temperature related to furnace performance to control the fuel delivery means and the combustion air delivery means for maximum furnace efficiency, minimum fuel consumption and minimum soot and smoke formation. In addition, the control circuit includes "hold fire" circuit which is operable in response to combustion-related temperatures and during periods when the demand temperature is met to control the fuel delivery means and the combustion air delivery means to maintain combustion in the combustion chamber.

Abstract: A furnace control apparatus for a downflow forced warm air furnace uses a microprocessor and thermostat to initiate and control the start-up of the furnace. During the initial start-up operation, the microprocessor receives an input signal from the thermostat indicative of the need for a furnace operation and produces an output signal for controlling, in combination with the thermostat which responds to the temperature of the space to be heated, an actuation of a gas valve to supply gas to the furnace. Subsequently, an analog temperature sensor in an air supply duct is used to supply another input signal through an analog-to-digital converter to the microprocessor representative of the air temperature in the duct. The microprocessor stores the value of the air temperature following the start-up of the burner and subsequently turns on an air circulator.

Abstract: A control circuit controls the delivery of fuel to a burner used to heat a heat exchanger in a furnace. A thermostat provides a fuel demand signal to a fuel valve causing the fuel valve to open to feed fuel to the burner to heat the heat exchanger. Once the heat exchanger is warmed to, for example, 250.degree. the blower is activated by a low temperature switch. A high temperature safety switch is used to shut off the fuel valve if the temperature of the heat exchanger gets dangerously high, such as 800.degree. F. A first switch is placed in series with the thermostat and the fuel valve and remains closed until the temperature of the heat exchanger rises above a first temperature, for example 500.degree. F. When this occurs the first switch opens so the flame extinguishes. Once the heat exchanger temperature drops to a second temperature, such as 350.degree. F., the first switch closes, thus resupplying fuel to the burner.

Abstract: A dual-rate fuel flow control system for the gaseous or liquid fuel supplied to the burner of a space heater, comprising a valve controllable to supply full fuel flow to the burner at the start of a heating cycle to deliver full heat to the heat exchanger chamber in which circulates the heat transfer fluid, and controllable to supply reduced fuel flow to the burner simultaneously with starting the circulating of the heat transfer fluid from the heat exchanger to the space to be heated.

Abstract: A control system for heating installations which is responsive to a pre-selected target air temperature and a pre-selected radiant heat output.

Abstract: An electric thermostat operative to be connected to a furnace or other temperature modifying apparatus to control its state of operation includes means for generating a desired temperature set-point signal and means for measuring ambient temperature at the thermostat. When the ambient temperature falls sufficiently below this set-point, the furnace is energized until the ambient temperature rises to a stored temperature level, also below the set-point. The system then monitors the peak ambient temperature reached during the following temperature overshoot resulting from the inertia of the furnace. The temperature differential between this limiting temperature obtained and the set-point is then added to the stored temperature value if the system did not obtain the set point temperature or substracted from the stored temperature value if the system exceeded the set-point value.

Abstract: An electronic thermostat operative to be connected to a furnace or other temperature modifying apparatus, to control its state of operation, includes means for generating a desired temperature set point signal and means for measuring ambient temperature on the thermostat. When the ambient temperature falls below the set point the furnace is energized for a predetermined period of time. The time of energization is increased or decreased by a small increment after each heating cycle depending upon magnitude of the temperature increase which occurred at the thermostat as a result of the heating cycle in order to adaptively achieve a predetermined temperature increase during the heating cycle and the thermal overshoot period which occurs following de-energization of the furnace.