Multistage Controls Patents (Class 236/1E)
  • Patent number: 6138467
    Abstract: A method of operating a refrigeration system in steady state operation drives the refrigerant system to the lowest capacity state which is still able to maintain operation within acceptable pressure and temperature limits. Generally, the system seeks to minimize the on and off compressor cycling. The lowest capacity state is achieved by throttling the compressor suction and by staging down the compressor operation from economized to normal and to unloaded mode while assuring that desired box temperature is maintained. Safety methods are incorporated into the system to ensure that the operation does not violate limits on suction pressure, discharge pressure, and compressor discharge temperature.
    Type: Grant
    Filed: December 16, 1998
    Date of Patent: October 31, 2000
    Assignee: Carrier Corporation
    Inventors: Alexander Lifson, Boris Karpman
  • Patent number: 5806762
    Abstract: An atomizing nozzle assembly, comprises a body; a nozzle head secured to the body, the nozzle including a chamber and an orifice for permitting water to flow out; a stem disposed within the chamber, the stem including a tip adapted to slide into or out of the orifice, thereby closing or opening the orifice, respectively; a piston secured to a rear end of the stem, the piston being slidably disposed within a cavity in the body; a spring disposed behind the piston adapted to bias the piston forward such that the tip is disposed within the orifice to close off the orifice when liquid to the nozzle assembly is cut off; a passageway within the body communicating with the chamber and the orifice, the passageway for connecting to a liquid supply to be atomized; and the tip including a resilient tubing adapted to provide a seal against the orifice when the tip is the closed position.
    Type: Grant
    Filed: May 16, 1997
    Date of Patent: September 15, 1998
    Assignee: DGH Systems, L.L.C.
    Inventors: D. Scott Herr, William Kane
  • Patent number: 5806760
    Abstract: An electronic two stage furnace controller may be used interchangeably, without modification thereof, with either a single or two stage thermostat to regulate the heating and cooling operation of a two stage heating/cooling furnace to which the controller is connected. The controller is operative to monitor the input it receives from the thermostat, automatically deduce whether the input is from a single stage thermostat or a two stage thermostat, and responsively regulate the operation of the furnace under a corresponding single stage thermostat heating or cooling mode, or a corresponding two stage thermostat heating or cooling mode.
    Type: Grant
    Filed: April 17, 1997
    Date of Patent: September 15, 1998
    Assignee: Rheem Manufacturing Company
    Inventor: Dennis R. Maiello
  • Patent number: 5405079
    Abstract: In a heating system with a plurality of heat sources, wherein at least a first heat source is normally activated at a first, higher ambient temperature and at least one additional heat source is normally activated at a second, lower ambient temperature, a method for maintaining a desired comfort level in a comfort zone when the first heat source is deactivated comprising the steps of: recognizing that the first heat source is deactivated; and initiating at least one of the additional heat sources when the first, higher ambient temperature is reached.
    Type: Grant
    Filed: July 8, 1993
    Date of Patent: April 11, 1995
    Assignee: Carrier Corporation
    Inventors: Timothy A. Neeley, Kevin D. Thompson
  • Patent number: 5400962
    Abstract: A system and method for controlling operation of a water heater provides generating a heating demand signal which a minimum level corresponds to a required heat input for maintaining water temperature in the water tank in case of no exogenous demand for water. Responsive to the heating demand signal, air flow from the forced draft blower and flow of combustible fluid from the combustible fluid delivery system are varied to produce combustion product over a minimum 15 to 1 ratio. This allows water heating to be varied to meet maximum expected exogenous demand or to maintain water temperature with no exogenous demand.
    Type: Grant
    Filed: October 27, 1993
    Date of Patent: March 28, 1995
    Assignee: PVI Industries, Inc.
    Inventors: Richard C. Adams, Charles L. Adams
  • Patent number: 5369597
    Abstract: A heat pump or air conditioning system includes a process for calculating on a real time basis the capacity contribution of each of a number of heating or cooling stages. The calculated contribution is utilized to determine the number of stages that need to be activated at any point in time in the heat pump or air conditioning system.
    Type: Grant
    Filed: December 21, 1992
    Date of Patent: November 29, 1994
    Inventor: Walter E. Bujak, Jr.
  • Patent number: 5341577
    Abstract: Carbon black is introduced into a granulating machine 3 through an inlet 1 and water is introduced into the same through an inlet 2 to prepare granulated carbon black, which is fed to a cylindrical rotary type dryer 5 through a line 4 and is dried. A product of carbon black is discharged through a line 6. Temperature in the dryer 5 is measured by a plurality of thermometers 10. A combustion control device performs the arithmetical processing of temperature data to obtain the initial point at which the state of the carbon black is changed from the constant rate of drying to the falling rate of drying. The control device controls each flow rate of fuel supplied from each line 7 or 8 to burners 9 for the front and rear half portions of the dryer by using the critical point and the temperature of the carbon black at the outlet of the dryer, whereby a temperature profile for the carbon black in the dryer 5 can be made stable for a long time.
    Type: Grant
    Filed: July 21, 1993
    Date of Patent: August 30, 1994
    Assignee: Mitsubishi Kasei Corporation
    Inventors: Iori Hashimoto, Motoki Numata, Jun Nishizawa, Tomiyuki Kamada
  • Patent number: 5317670
    Abstract: A hot water system for connection to a water supply and a local hot water usage system, comprising a plurality of series-connected reserve tanks and demand tanks for receiving water from the water supply, heating the received water to a desired temperature within the reserve and demand tanks, and supplying the heated water to the local hot water usage system as it is demanded. A controlling device is provided for sequencing the operation of the reserve and demand tanks relative to peak power consumption hours and off-peak hours. Specifically, each of the tanks is provided with one or more thermostats which are selectively enabled or disabled by the controlling device at predetermined times. The one or more thermostats are, in turn, connected to one or more heating coils or maintenance coils. The reserve tanks and demand tanks may be operated under control of the controlling device in any of three modes, as follows: maintenance mode, enable mode, and disable mode.
    Type: Grant
    Filed: October 19, 1992
    Date of Patent: May 31, 1994
    Inventor: Paul Elia
  • Patent number: 5271556
    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.
    Type: Grant
    Filed: August 25, 1992
    Date of Patent: December 21, 1993
    Assignee: American Standard Inc.
    Inventors: Robert W. Helt, Carl L. Garrett, James T. Vershaw
  • Patent number: 5172654
    Abstract: A microprocessor-based sequencer for a multiple boiler heating system which allows the plural boilers to operate in a base load mode whereby one or more boilers can be made to operate at their optimum operating points and as the heating demand changes, a swing boiler accommodates the change, leaving the other(s) at their Preferred Load value until the swing boiler can no longer satisfy the demand change. At this point, the sequencer adjusts the base load level away from the preferred load set-point.
    Type: Grant
    Filed: February 10, 1992
    Date of Patent: December 22, 1992
    Assignee: Century Controls, Inc.
    Inventor: Leo P. Christiansen
  • Patent number: 5119884
    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.
    Type: Grant
    Filed: November 30, 1989
    Date of Patent: June 9, 1992
    Assignee: Johnson Service Company
    Inventor: David P. DeBoer
  • Patent number: 4696427
    Abstract: The present invention relates to transforming a pre-existing heating installation comprising a main heat generator such as a boiler which is associated with a modulating mixer valve controlled by a P or PD type regulator which is responsive to outside temperature and to the departure temperature of the heating water.
    Type: Grant
    Filed: March 25, 1986
    Date of Patent: September 29, 1987
    Assignee: Electricite de France
    Inventors: Jacky Pichot, Jacques Oddou
  • Patent number: 4534321
    Abstract: The disclosure relates to an apparatus for controlling a number of boilers which are, in terms of water engineering, interconnected in series and each are provided with their control equipment having a first and a second switch, the first switch being arranged to generate a signal "permission to increase", and the second switch being arranged to generate a signal "permission to reduce", whereby the boilers are given priority ranking in such a manner that the first boiler must always attain full output before a subsequent boiler can commence to be connected in and so that a subsequent boiler must always be reduced to zero output before a preceding boiler can commence to reduce its output.
    Type: Grant
    Filed: November 5, 1982
    Date of Patent: August 13, 1985
    Inventor: Sten A. Rydborn
  • Patent number: 4445567
    Abstract: A two-stage thermostat means for an add-on heat pump installation provides separated control of a furnace and a heat pump. The two-stage thermostat means utilizes a single pole, single throw switch means, and a single pole, double throw switch means to properly stage and control a heat pump and a fossil fueled furnace so that they do not overlap. The control of the temperature of the heated area is independent of any need to connect a circuit between the thermostat in the heated area and any type of thermostat at the heat pump itself.
    Type: Grant
    Filed: February 26, 1982
    Date of Patent: May 1, 1984
    Assignee: Honeywell Inc.
    Inventor: Lorne W. Nelson
  • Patent number: 4427055
    Abstract: A forced air heating and cooling system employs a water source heat pump as the primary heating source and as a back-up or supplementary source of cooling. Supplementary heating is supplied by an electrical heater such as resistance heater, while primary cooling is provided by a water coil heat exchanger. Separate thermostats control the heat pump on the one hand, and the resistance heater and water coil heat exchanger on the other hand; the two thermostats can be combined in a simple unit. The thermostats automatically control two valves which control system water flow. For cooling, a first valve opens to permit water flow in series through first the water coil and then the heat pump. For heating, only the second valve is opened to bypass the water coil and deliver water directly to the heat pump. The water is ground water derived from a well, spring or lake. The thermostats automatically switch on the heat pump, heater and/or heat exchanger to effect the necessary heating or cooling.
    Type: Grant
    Filed: October 8, 1980
    Date of Patent: January 24, 1984
    Assignee: Memtel Corporation
    Inventor: Michael G. Heavener
  • Patent number: 4412581
    Abstract: The invention relates to a heating installation which includes a boiler and a heat pump. The heat pump has a multi-stage compressor. Graded threshold value operating switches for the multi-stage compressor and the boiler are provided. A control unit which includes comparator and integrator units functions to select compressor and boiler outputs in response to comparisons between indoor and outdoor temperatures made by the comparator unit.
    Type: Grant
    Filed: March 1, 1982
    Date of Patent: November 1, 1983
    Assignee: Danfoss A/S
    Inventors: Kristian Iversen, Henning Hansen
  • Patent number: 4350144
    Abstract: A system for heating domestic hot water includes solar collectors for raising the temperature of the water in the usual hot water storage tank. When a tap is opened, the water is drawn out of the tank and directed through a mixing valve which checks the temperature of the water and, if necessary, adjusts the temperature to an intermediate temperature somewhat below the temperature at which the water is to be used. The water then passes through a heater in which the temperature of the water is quickly raised to the elevated temperature at which it is normally used in households.
    Type: Grant
    Filed: August 18, 1980
    Date of Patent: September 21, 1982
    Assignee: Stanford Associates, Inc.
    Inventor: John R. Beckwith
  • Patent number: 4332352
    Abstract: A multistage thermostat is operated by comparing the thermostat setpoint and the sensed temperature over a continuous series of discrete intervals of time. When a sudden change occurs between the sensed temperature and the setpoint, the magnitude of this change is evaluated in a comparator means and if necessary the system is reset to compensate for the change to operate in the most efficient manner. The adjustment of a constant supplied to an integrating circuit that forms part of a signal processing circuit means for the thermostat means provides the adjustment when the predetermined level of change is made.
    Type: Grant
    Filed: January 30, 1981
    Date of Patent: June 1, 1982
    Assignee: Honeywell Inc.
    Inventor: Thomas S. Jaeger
  • Patent number: 4325224
    Abstract: A transport refrigeration system having the capability of either heating or cooling at high or low speed and with the compressor loaded or unloaded is controlled by a temperature control system including a heat relay 1K and a speed relay 2K, and has an auxiliary control relay CR which is operative to maintain the compressor speed at a low speed in the temperature band 48 closely above and below the setpoint temperature, and will further maintain the low speed of the compressor for a predetermined time as the temperature rises above or below the narrow temperature band through time delay means 46 which, if uninterrupted in operation for the predetermined time period will drop out the control relay so the system can resume higher speed operation.
    Type: Grant
    Filed: April 29, 1980
    Date of Patent: April 20, 1982
    Assignee: Thermo King Corp.
    Inventor: Leland L. Howland
  • Patent number: 4302663
    Abstract: A space heater having two heating elements and a motor/fan combination for circulating air over the heating elements to supply heated air to an environment includes a system for controlling the operation of the heating elements and the motor in response to heating requirements of the environment. The control system includes a first circuit for sensing temperature to determine a heating requirement to maintain a desired ambient temperature of the environment, a second circuit for independently activating and deactivating the heating elements in according with the heating requirements determined by the first circuit, and a third circuit for activating, deactivating, and variably controlling the volume of air circulated by the motor/fan in accordance with heating requirements determined by the first circuit. The heater housing includes a main housing portion housing the heating elements, an ambient air intake opening, a heated air exhaust vent, and the motor/fan.
    Type: Grant
    Filed: February 4, 1980
    Date of Patent: November 24, 1981
    Assignee: Arvin Industries, Inc.
    Inventors: Amos E. Chesnut, Carl R. Pittman
  • Patent number: 4293027
    Abstract: A control system for space heating and cooling units which includes modulated damper means for controlling entry of outside air. Temperature sensitive resistances sense the outside air temperature, the temperature in the space, and the temperature of return air. When cooling is required, the damper can be opened. When the return air temperature is greater than the outside air temperature, the outside air damper is modulated in opening direction when the space temperature rises above a minimum comfortable space air temperature so that the outside air is used for cooling. When the space temperature falls to a temperature below the minimum comfortable space air temperature, the outside air damper can be fully closed.
    Type: Grant
    Filed: October 25, 1977
    Date of Patent: October 6, 1981
    Assignee: Energetics Systems Corp.
    Inventors: James R. Tepe, Robert P. Sandor, Bernard W. Wesselman, David R. Woeste
  • Patent number: 4272012
    Abstract: A plurality of temperature conditioning units are divided into groups with the groups being sequentially and repetitively, one after the other, enabled for a first preset number of timing intervals and then disabled for a second preset number of timing intervals. The sum of the first and second preset number of timing intervals is equal to the total number of groups so that at any given time, but on a rotating basis, the first preset number of groups of units is enabled and the second preset number is disabled. A setback feature which can be overriden by a thermostatic control is provided for off hours. An alarm system provides warning of abnormal operation of any one of the units as detected by excessive cycling.
    Type: Grant
    Filed: March 9, 1979
    Date of Patent: June 9, 1981
    Inventors: John R. Molnar, Earl H. Mechling, William L. Bell
  • Patent number: 4270362
    Abstract: Temperature and humidity electrical/electronic control circuits and apparatus to maintain a room at a constant temperature and humidity. The control system is adapted to an environmental condition controller for year-around cooling utilizing a liquid recirculating to an outside coil for free cooling or free reheat dehumidification. The controls provide a sequencing function to actuate one or more temperature and/or humidity conditioners in response to the degree and percentage of change. The circuit provides a ramp function signal for proportional control over an initial temperature range of free cooling and step controls over other predetermined temperature ranges. The circuit comprises a high fidelity ramp generator linearly responsive to the degree of temperature change up to a predetermined set point. A dehumidification signal is developed and fed to the same ramp generator to carry out air cooling to remove moisture.
    Type: Grant
    Filed: March 19, 1979
    Date of Patent: June 2, 1981
    Assignee: Liebert Corporation
    Inventors: Frederick N. Lancia, Albert O. Kesterson, Edward K. Feeney, Ralph C. Liebert
  • Patent number: 4259847
    Abstract: An air conditioning system is disclosed in which the air conditioning capacity is stepped to a lower level upon reduced sensible air conditioning demand. The stepped reduction involves both a stepped reduction of blower capacity and a stepped change of the heat exchange fluid flow at the heat exchanger modifying the temperature of the air. Several embodiments are disclosed.
    Type: Grant
    Filed: August 16, 1978
    Date of Patent: April 7, 1981
    Assignee: The Trane Company
    Inventor: Richard H. Pearse, Jr.
  • Patent number: 4248053
    Abstract: In the main intended application of the arrangement according to the invention, that is, using a reversible motor compressor in a heat pump in a refrigerating or air conditioning system, it is desirable to insure a delay during reversal of the direction of compressor operation. A control arrangement is provided in which the control system controls the direction of motor operation or compressor capacity in accordance with temperature conditions, the system including control means for effecting operation in a low capacity direction or condition, or alternatively in a high capacity direction or condition in response to one set, and another set, respectively, of temperature conditions and with timer means delaying a restart of the compressor motor for at least a predetermined time in response to a condition of the control means operative to initiate a change in the operating direction or condition of the compressor when it restarts.
    Type: Grant
    Filed: March 5, 1979
    Date of Patent: February 3, 1981
    Assignee: Westinghouse Electric Corp.
    Inventor: Francis J. Sisk
  • Patent number: 4241871
    Abstract: An automatic ventilation system for an enclosure for animals, fowl and the like, whereby plural banks of exhaust fans are controlled by respective thermostats set for operation at respective individual temperatures over an operating range of temperatures, while movable baffles or the like at air inlet apertures are adjusted under the control of a differential-pressure sensing means to regulate the rate of flow of air through the inlet apertures to maintain a desired difference between the barometric pressure within and without the enclosure irrespective of the number of banks of fans in operation at a given time; when the thermostat set at the highest temperature is actuated, the movable baffles are adjusted for maximum flow irrespective of the output of the differential-pressure sensing means, thereby establishing a second, and smaller, differential pressure; upon failure of the primary power source, a second power source is automatically utilized to adjust the inlet baffles to a position of maximum opening,
    Type: Grant
    Filed: November 27, 1978
    Date of Patent: December 30, 1980
    Inventors: Alfred T. Newell, III, Alfred T. Newell, Jr.
  • Patent number: 4199690
    Abstract: A control system for actuators which can be separately energized. The controller of the system has a two-position control unit and a three-position control unit and is followed by constant current source circuits, a stepping switch unit with threshold switches having a stepped reference voltage, as well as a logic circuitry interconnecting the stepping switch unit and the two-position control output. Prevention of overshoot or undershoot is achieved by means of additional logic circuitry interconnecting the switches at the positive and negative output of said three-position control unit, said two-position control output, and said first mentioned logic circuitry between the stepping switch unit and two-position control output. In this manner overshoot can be prevented by quickly de-energizing the actuator, which was last energized, when the actual value in the controlled system closely approaches the set-point or reference value.
    Type: Grant
    Filed: August 15, 1977
    Date of Patent: April 22, 1980
    Assignee: Automation Industries, Inc.
    Inventor: Frank Meyer
  • Patent number: 4193781
    Abstract: Condensing head pressure in a refrigeration system having its condenser exposed to low outside ambient temperatures is controlled to provide the minimum head pressure required for a given mode of operation. A hierarchy of operating modes, each with its associated pressure is established, including normal refrigeration, evaporator defrost and heat reclaim. The control system prevents system head pressure from going below the minimum required for the operating mode in effect at a given time, with modes requiring higher pressure overriding lower pressure modes when required. In heat reclaim operation, high pressure gas from the compressor is diverted through a heat reclaim coil, and a subcooling sensor or other sensing means controls system head pressure to the minimum pressure that will maintain full condensing in the heat reclaim coil, which is the most economical mode of operation.
    Type: Grant
    Filed: April 28, 1978
    Date of Patent: March 18, 1980
    Assignee: McQuay-Perfex Inc.
    Inventors: Kenneth E. Vogel, Jerome D. Powlas
  • Patent number: 4191027
    Abstract: An apparatus for cooling brine comprising a plurality of refrigerating units connected to a slow-current tank for brine in such a manner said refirgerating units are associated with successive portions of brine in said slow-current tank from the downstream side to the upstream side of said tank, one by one. The number of said refrigerating units taking part in the cooling work is increased and decreased in accordance with the temperature of said brine in said slow-current tank. The connection of said refrigerating units is selectively switched from series to parallel and vice versa with one another, with respect to the brine flow in said slow-current tank. Said means for switching the connection of said refrigerating units from series to parallel and vice versa are constituted by fluid element type shunting devices.
    Type: Grant
    Filed: July 27, 1977
    Date of Patent: March 4, 1980
    Assignee: Kabushiki Kaisah Maekawa Seisakusho
    Inventor: Wahei Inoue
  • Patent number: 4168719
    Abstract: A gas control device for controlling the gas supply to the burner of a domestic hot water boiler has two main valves arranged in series in the gas flow path so as when closed to define a chamber between them. A second chamber is communicable with this chamber through an auxiliary valve which is open when the main valves are closed and closed when the main valves are open. A shut-off valve is responsive to the pressure in the second chamber so as to close the flow path if gas leaks through the upstream main valve when supposedly closed. The subsequent closing of the auxiliary valve when the main valves are later opened maintains the pressure in the second chamber so that the shut-off valve remains closed.
    Type: Grant
    Filed: March 31, 1977
    Date of Patent: September 25, 1979
    Assignee: Steel Radiators Limited
    Inventor: Edward J. Renshaw
  • Patent number: 4152902
    Abstract: A device for controlling a single variable capacity compressor, or multiple variable capacity compressors in either parallel flow or series flow chilling systems, senses temperature and load conditions and uses feedback in conjunction with synchronously and asynchronously timed logic circuitry to automatically control loading, unloading and sequencing of the compressor or compressors in the system in selected increments, thereby yielding a significant reduction in energy consumption as well as increased precision in maintaining a desired chill temperature. Additional circuitry provides for remote manual control as well as safety shut-off and failure indication. Alternative embodiments using solid state logic, including a microprocessor embodiment, are also disclosed.
    Type: Grant
    Filed: May 23, 1977
    Date of Patent: May 8, 1979
    Inventor: Lawrence E. Lush
  • Patent number: 4141408
    Abstract: A supplementary heat control for a heat pump system includes thermostatic sensors on the downstream side of the heat pump heating coil. The sensors upon sensing temperature differentials in the heated air stream which indicate the need for supplemental heat operate relays. The relays, in turn, activate power input to supplementary heating coils downstream from the thermostatic sensors. A plurality of sensors are disclosed for sensing differential temperature differentials and thus permitting staging of supplementary heat.
    Type: Grant
    Filed: June 16, 1976
    Date of Patent: February 27, 1979
    Assignee: Rheem Manufacturing Company
    Inventor: Jack V. Garnett
  • Patent number: 4140067
    Abstract: A furnace control system to control burner operation of a multifuel furnace to reduce primary fuel consumption of either oil or gas of the multifuel furnace. The system controls a primary fuel to initially kindle a secondary fuel when the fire reaches a self-sustaining burning rate, the primary fuel is shut off but the burner fan continues to run to force a draft and insure complete combustion of the secondary fuel and the volatile gases. The furnace control system is utilized as original equipment manufacturer incorporated into the controls for a burner of a multifuel furnace or as a retrofit furnace control system to control the burner operation of the multifuel furnace.
    Type: Grant
    Filed: October 27, 1977
    Date of Patent: February 20, 1979
    Assignee: T. Jensen Associates Inc.
    Inventor: Thomas A. Jensen
  • Patent number: 4114807
    Abstract: This system is of the power management type and is for controlling the operation of the various stages within a number of units such as heating, ventilation, and air conditioning units commonly referred to as HVAC units which may be of conventional design and for use in commercial buildings.The system permits only a limited number of stages, fewer than the total number contained in all the HVAC units to be predeterminedly operated at one time but preferably stores an indication of all stages which are demanding operation of the total number of HVAC units in the building. If a greater number of stages are demanding than the system has been pre-set to operate then an indication of the unsatisfied or inhibited unit or units is stored. If this condition persists for a predetermined period of time such as 5 minutes then the longest running stage, even though it is sill demanding, is dropped or stopped and the longest waiting inhibited stage is satisfied or started.
    Type: Grant
    Filed: March 23, 1976
    Date of Patent: September 19, 1978
    Assignee: Conservation Controls Corp.
    Inventors: Melvin L. Naseck, Mark R. Hickman
  • Patent number: 4085594
    Abstract: A control system for automatically controlling the operation of a plurality of fans for a cooling tower so that the minimum number of fans and the lowest speeds are used to provide the required cooling necessary at any one time. The fans are individually controlled in response to the temperature of the working fluid, to be either off or operated at a low or high speed so that as the temperature of the working fluid increases, more fans are turned on first to their low speed and then to their high speed. Safety features are provided for starting the system and for changing the speeds of the fans to prevent damage to the control system and unnecessary wear on the fan motors.
    Type: Grant
    Filed: February 14, 1977
    Date of Patent: April 25, 1978
    Assignee: Suntech, Inc.
    Inventor: Robert Mayer
  • Patent number: 4081691
    Abstract: The present device incrementally adds or subtracts power units to and from a heating or cooling system and employs a major control board into which are plug-connected a plurality of minor control boards. The minor control boards have varying designs. Some are designed to accept different signals from different types of temperature monitoring means and are designed to convert those different signals into common command signals, while other minor control boards are designed to accept those command signals in order to communicate with and control yet others of said minor control boards to effect a turning on and/or turning off of said heating or cooling power units according to at least two different modes of operation. The major control board provides a power source for the minor control boards and provides the circuit paths to enable the minor control boards to transmit signals among any set of such mounted boards.
    Type: Grant
    Filed: August 5, 1976
    Date of Patent: March 28, 1978
    Assignee: Athena Controls Inc.
    Inventors: Egils Evalds, Ernest F. Coccio
  • Patent number: 4072866
    Abstract: A proportional temperature control system using a linear time delay circuit provides an output voltage that is similar to the output voltage of a thermostat but delayed in time. The delay circuit is a linear rate time delay system that compares a called for voltage shift at its input to the output voltage of an integrator circuit to provide a substantially linear rate of time delay. The comparator circuit and the integrator circuit are separated by a limiter so that regardless of the amount of the initial offset in voltage at the comparator, the rate of integration is always maintained the same.
    Type: Grant
    Filed: December 1, 1976
    Date of Patent: February 7, 1978
    Assignee: Honeywell Inc.
    Inventor: John L. Kabat
  • Patent number: 4024378
    Abstract: An electrical circuit for a heating system has a plurality of electrical resistance heating elements and a blower all controlled by a plurality of electro-thermally actuated relays. The circuit is arranged so that the heating elements are sequentially energized and de-energized and so that the blower is maintained in operation at all times that any one of the heating elements is energized. A thermostat controls the operation of the relays, the second and the last of which each having switches connected in series circuits with the actuator of the first relay and in parallel with the thermostat so as to maintain blower operation, which is controlled by the first relay, when the thermostat opens.
    Type: Grant
    Filed: May 1, 1975
    Date of Patent: May 17, 1977
    Assignee: Robertshaw Controls Company
    Inventor: Harold A. McIntosh
  • Patent number: 4019679
    Abstract: A heating arrangement, in which the circulating heat transfer medium for radiators is heated by condensation of a refrigerant in a heat pump, is controlled by relays in the energizing circuits of the several, independently driven pumping units of the compressor in the heat pump in response to the difference between the temperature of the atmosphere outside the heated area and the temperature of the circulating heat transfer medium to reduce the pumping energy consumed in response to the rising temperature of the heat transfer medium, and thereby to improve the efficiency of the heating arrangement.
    Type: Grant
    Filed: December 15, 1975
    Date of Patent: April 26, 1977
    Assignee: Interliz Anstalt
    Inventors: Alfred Vogt, Herbert Bolter
  • Patent number: 4009825
    Abstract: An SCR motor speed controller in a forced air heating and/or cooling system has a relay-operated potentiometer with a variable voltage tap which controls the speed of the fan motor in accordance with the total demand from individual room thermostats. Each room thermostat controls the operation of a corresponding control relay to short-circuit a corresponding part of the potentiometer on one side of its variable-voltage tap and to add in a corresponding part of the potentiometer on the opposite side of its variable voltage tap in response to a demand from the thermostat.
    Type: Grant
    Filed: February 11, 1976
    Date of Patent: March 1, 1977
    Inventor: George M. Coon
  • Patent number: 3999934
    Abstract: In a thermostat control system including means for modulating the fuel flow to a burner above a predetermined level necessary for combustion, the improvement comprising an ignition circuit adapted to provide a larger fuel flow initially to the burner including in one embodiment a bimetallic switch connected for thermal communication with the burner cavity for completing the circuit of the above thermostat control system after the burner cavity reaches a predetermined temperature.In a second embodiment, a time delay circuit is provided instead of the bimetallic switch, such time delay circuit providing a larger fuel flow to the burner during the ignition time interval.
    Type: Grant
    Filed: May 23, 1975
    Date of Patent: December 28, 1976
    Assignee: Robertshaw Controls Company
    Inventors: William W. Chambers, James N. Brooks
  • Patent number: 3993120
    Abstract: A space thermostat for controlling the two-stage operation of both heating and cooling apparatus includes two single-pole, double-throw mercury type switches operatively connected to a single bimetallic coil. One switch energizes stage one of the heating apparatus when tilted in one direction and energizes stage two of the cooling apparatus when tilted in the other direction. The other switch energizes stage two of the heating apparatus when tilted more in the direction which effected the energizing of stage one of the heating apparatus and energizes stage one of the cooling apparatus when tilted less in the direction which effected the energizing of stage two of the cooling apparatus. The switches are adjustably mounted with respect to each other so that the differential between stages can be adjusted to be the same as the differential of each switch.
    Type: Grant
    Filed: November 18, 1974
    Date of Patent: November 23, 1976
    Assignee: Emerson Electric Co.
    Inventors: Willard J. Iberg, Claude H. Keathley
  • Patent number: 3982552
    Abstract: A dishwashing machine having a gas-fired heater is provided with a flue structure having wall portions common to the tank and wash chamber of the machine. While the machine is running liquid splashes against these wall portions and exchanges heat therewith. When the water circulation system is stopped, the heater is limited to a standby condition which is predetermined to maintain these wall portions at substantially the same temperature as during running conditions.
    Type: Grant
    Filed: June 26, 1975
    Date of Patent: September 28, 1976
    Assignee: Hobart Corporation
    Inventor: Louis F. Fraula
  • Patent number: 3969069
    Abstract: Burners of an oven are operated to satisfy heat loads changeable between a high load and substantially smaller loads. At least under the smaller loads the burners are cyclically controlled in a cycle of time periods T-1 and T-2. During the periods T-1 the burners are steadily regulated to maintain a uniform temperature in the oven. For periods T-2 the burners are periodically controlled to admit one of two selected magnitudes of fuel flow to the oven. At least under the smallest loads the latter magnitudes are periodically controlled to be zero or close to zero.
    Type: Grant
    Filed: April 10, 1974
    Date of Patent: July 13, 1976
    Assignee: Koppers-Wistra-Ofenbau Gesellschaft mit beschrankter Haftung
    Inventor: Rudiger Knaak
  • Patent number: 3964466
    Abstract: A parallel water heating system having a plurality of water heaters supplying heated water to a plurality of water consuming loads. The water consuming outlet conduit from each of the water heaters includes a temperature responsive control valve that controls the flow rate of hot water from that particular heater to the various parallel connected loads. Each of these control valves is selected to be fully open when the water temperature is above an upper predetermined value and fully closed when below a lower predetermined value. Between the upper and lower predetermined values the valve preferably varies from fully open to fully closed by an amount that is about linearly proportional to the decrease in temperature.
    Type: Grant
    Filed: March 31, 1975
    Date of Patent: June 22, 1976
    Inventor: Jack G. Ohringer
  • Patent number: 3935855
    Abstract: Gas fired air heater for a central heating system comprising a heat exchanger in which are arranged a series of parallel rows of vertical heat exchange tubes, the lower ends of which are connected to a joint burner compartment and the upper ends of which are connected to a joint flue compartment. Two opposite lateral sides of the heat exchanger are connected to air supply and discharge compartments respectively for feeding the air to be heated transversely through the heat exchanger. The lateral air supply and discharge compartments have air inlet and outlet connections at their top and bottom walls only. One of said lateral air compartments is closed at one end and is connected to a fan at the opposite end, whereas at least one end of the other lateral air compartment is connected to a main duct for discharge of the heated air.
    Type: Grant
    Filed: April 24, 1974
    Date of Patent: February 3, 1976
    Assignee: N.V. Werktuigenfabrieke Mulder
    Inventor: Cors van Vliet