Hot Air Furnace Patents (Class 236/46E)
  • Patent number: 5971284
    Abstract: A method and apparatus of regulating cycles of a burner in a forced air heating system. A control unit uses a sensor at an output of a heat exchanger to make measurements of a temperature of air output from the heat exchanger. The control unit observes temperature measurements, after the burner has turned on. It initializes a confirmation interval when two consecutive temperature measurements are the same. If the temperature is the same at an end of the confirmation interval. The invention interrupts firing of the burner for an interrupt interval. The interrupt interval is insufficient to allow the heat exchanger to cool below a temperature useful for heating below which the circulation fan would shut off.
    Type: Grant
    Filed: March 25, 1998
    Date of Patent: October 26, 1999
    Assignees: Intellidyne, LLC, Harvey Schwartz
    Inventor: Jack Hammer
  • Patent number: 5582233
    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.
    Type: Grant
    Filed: February 22, 1995
    Date of Patent: December 10, 1996
    Inventor: Paul V. Noto
  • Patent number: 5377909
    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.
    Type: Grant
    Filed: December 10, 1993
    Date of Patent: January 3, 1995
    Assignee: Consolidated Industries Corp.
    Inventor: Michael E. Kirkpatrick
  • Patent number: 5340028
    Abstract: A method for providing a low fire mode and a high fire mode of a heating cycle in a current cycle of a furnace as a function of the previous heating cycle wherein the current heating cycle is a function exclusively of time run in low fire mode and time run in high fire mode of the previous heating cycle, comprising the steps of: (1) determining the existence of a heating load to be satisfied; (2) running burners in low fire mode for a first time interval that does not exceed a predetermined limit, L.sub.des ; (3) running the burners in high fire mode for a second time interval until the heating load is satisfied; (4) calculating a BtU load requirement, as a function of the first time interval and the second time interval; and (5) determining the desired low fire mode time limit, L.sub.des, for the next cycle from the calculated BtU load requirement.
    Type: Grant
    Filed: July 12, 1993
    Date of Patent: August 23, 1994
    Assignee: Carrier Corporation
    Inventor: Kevin D. Thompson
  • Patent number: 5337952
    Abstract: In a heating system containing twinned furnaces capable of independently operating at multiple levels, a method for providing multiple heating modes to satisfy a required heating load during a given cycle, there being some total number of heating modes, wherein each heating mode may be activated for a time interval whose length is a function of furnace activity during the most recent previous cycle.
    Type: Grant
    Filed: July 28, 1993
    Date of Patent: August 16, 1994
    Assignee: Carrier Corporation
    Inventor: Kevin D. Thompson
  • Patent number: 5326026
    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 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.
    Type: Grant
    Filed: July 27, 1993
    Date of Patent: July 5, 1994
    Assignee: Arnold D. Berkeley
    Inventors: Donald E. Jefferson, Arnold D. Berkeley
  • Patent number: 5326025
    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.
    Type: Grant
    Filed: July 8, 1993
    Date of Patent: July 5, 1994
    Assignee: Carrier Corporation
    Inventors: Daniel J. Dempsey, Kevin D. Thompson
  • Patent number: 5011073
    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.
    Type: Grant
    Filed: November 3, 1989
    Date of Patent: April 30, 1991
    Assignee: Cam-Stat, Inc.
    Inventors: Lowell F. Izaguirre, Sr., Jose M. Perotti
  • Patent number: 4951870
    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.
    Type: Grant
    Filed: February 21, 1990
    Date of Patent: August 28, 1990
    Assignee: Carrier Corporation
    Inventors: Gary W. Ballard, John D. Stout
  • Patent number: 4907737
    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.
    Type: Grant
    Filed: March 30, 1989
    Date of Patent: March 13, 1990
    Assignee: R. E. Phelon Company, Inc.
    Inventor: Roger W. Williams, Jr.
  • Patent number: 4838482
    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.
    Type: Grant
    Filed: February 26, 1988
    Date of Patent: June 13, 1989
    Assignee: Honeywell Limited
    Inventor: John H. Vogelzang
  • Patent number: 4815524
    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.
    Type: Grant
    Filed: June 29, 1987
    Date of Patent: March 28, 1989
    Assignee: Carrier Corporation
    Inventors: Daniel J. Dempsey, Gary W. Ballard
  • Patent number: 4667874
    Abstract: An auxiliary heating/cooling system controller is connected in series between the household thermostat and the furnace burner valve and compressor. The controller includes a timing control which is responsive to a preset time interval valve and the plenum temperature to cycle the furnace burner on and off in order to moderate the temperature of the furnace heat exchanger, thus improving furnace efficiency. Upon installation the controller is programmed with a digital valve corresponding to the delay between a call for heat from the household thermostat and the initiation of the furnace fan. This value is then used to set a timer in the controller which synchronizes the initiation of the duty cycle control of the burner to the start of the fan at the beginning of a heating cycle, and to control the cycle time of the burner. A plenum thermostat monitors the temperature of the air produced by the furnace and if the air exceeds a predetermined limit the OFF time of the burner is increased.
    Type: Grant
    Filed: July 23, 1985
    Date of Patent: May 26, 1987
    Assignee: Harold R. Johnson
    Inventors: Harold R. Johnson, Steven E. Lombardi
  • Patent number: 4638942
    Abstract: An adaptive microprocessor control system and method provide a low heat mode and a high heat mode of a heating cycle in a furnace dependent upon the performance of the previous heating cycle. The duration of the low heat mode and subsequent high heat mode period is a function of the previous low heat mode duration, previous high heat mode duration, and the time period between the end of the previous heating cycle and the beginning of the next heating cycle. The control and method utilize a single-stage thermostat for providing the dual rates of heating.
    Type: Grant
    Filed: December 2, 1985
    Date of Patent: January 27, 1987
    Assignee: Carrier Corporation
    Inventors: Gary W. Ballard, Robert M. Mamot
  • Patent number: 4595139
    Abstract: A control system for an electrically energized humidifier used with a hot-air furnace including an electric time-delay circuit and control means for manually adjusting the time delay. Each time the thermostat for the system energizes the furnace the humidifier is energized for the predetermined time delay or until the furnace is de-energized, whichever occurs first. The time delay is manually adjusted so that it is longer than the energization cycle of the furnace in warm weather and shorter than the energization cycle of the furnace in cold weather. It is also manually adjusted so that in cold weather at the maximum energization cycle, the humifidier does not produce condensation within the building. The relative humidity of the conditioned air thus decreases proportionately to increases in the atmospheric temperature.
    Type: Grant
    Filed: November 13, 1984
    Date of Patent: June 17, 1986
    Inventor: Michael R. Levine
  • Patent number: 4502625
    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.
    Type: Grant
    Filed: August 31, 1983
    Date of Patent: March 5, 1985
    Assignee: Honeywell Inc.
    Inventor: Dale A. Mueller
  • Patent number: 3989928
    Abstract: A method and apparatus for cyclically controlling the energization of water heaters in residential homes on a daily and seasonal temperature basis. The apparatus includes a pair of clock timers each having a disk for supporting a plurality of relay actuators in spaced relationship to one another. The relay actuators open and close associated relays which couple power from a suitable source to the water heater via a seasonal thermostatic switch. The thermostatic switch connects one or the other of the relays in circuit with the water heater. On one of the disks the actuators are spaced for "summer" load conditions so that power to the water heater is inhibited for a substantial portion of the time in each day when "summer" power demand is greatest, that is, between noon and 8:00 p.m. On the other disk the actuators are spaced for "winter" load conditions so that power to the water heater is inhibited for a substantial portion of the time when "winter" power demand is greatest, that is, between 4:30 and 9:30 p.
    Type: Grant
    Filed: April 1, 1975
    Date of Patent: November 2, 1976
    Inventors: Robert L. Scragg, Alfred B. Parker
  • Patent number: 3945564
    Abstract: A temperature control system for providing an automatic reduction in the temperature of a room or a house during the nighttime hours which requires only the conventional two conductor wiring between the furnace and the thermostat thereby avoiding the necessity of adding to or replacing the existing wiring between the furnace and the thermostat. The system includes a temperature responsive element, a heater near the temperature responsive element for providing supplemental heating of the element, a conventional furnace control, a clock-operated current control for the heater, and a diode steering circuit for directing one portion of an alternating current waveform through the heater current control and the heater, and another portion of the alternating current waveform through the temperature responsive element and the furnace control for providing independent control of the heater and the furnace control.
    Type: Grant
    Filed: June 24, 1974
    Date of Patent: March 23, 1976
    Assignee: Novo Products, Inc.
    Inventor: Jon Smallegan