Showing papers on "Thermostat published in 1995"

Wireless remote temperature sensing thermostat with adjustable register

Abstract: A wireless remote temperature sensing and control thermostat system for regulating air ducted air conditioning systems incorporating a normal mode and a remote control mode, including a combination thermostat and radio-frequency receiver unit, a radio-frequency transmitter, and an adjustable register. In the normal mode, a reference temperature is set by the thermostat for the temperature throughout the entire air conditioned structure. In the remote control mode, the local temperature sensing and control functions of the thermostat are disabled and the transmitter unit will take over the temperature sensing at the remote site which, in turn, then will control the thermostat unit. As a result, the users will be able to more accurately control their own personal environment.

A thermostat system having an optimized temperature recovery ramp rate

Abstract: An adaptive recovery method for a setback thermostat using the intersection of the space temperature with a sloped recovery temperature line which approximates the change in temperature as a function of time during recovery of the temperature controlled space from a setback temperature, to determine the time at which recovery to the occupancy temperature should begin. The thermostat starts recovery when the current space temperature crosses the recovery temperature line. A useful feature of the apparatus and method which implement the invention, computes and constantly updates the slope of the temperature recovery line. The update of the temperature recovery line slope is based on miss time, i.e., the time between actually achieving the desired next set point temperature and the next set point time associated with the next set point temperature, the space temperature, the outdoor air temperature, the temperature recovery ramp rate during the previous recovery period, and the current and past thermal time constants. If the heating or cooling load on the space changes, the current space temperature will cross the recovery temperature line at a different time, causing recovery to start at a time more compatible with the current heating or cooling load in order to complete recovery at or near the desired time. Variables may be added to the system.

Temperature control with stored multiple configuration programs

Abstract: A thermostat which is configurable to be used with conventional fossil fuel furnaces, electric furnaces, heat pumps and other air conditioning equipment and fans. A setup program is included which requires an installer to enter data specific to the type of HVAC plant installed in the building with the thermostat.

Electronic Thermostat Having High and Low Voltage Control Capability

Abstract: An electronic thermostat having high and low voltage control capability and varied functional capabilities. The thermostat is particularly suited for use with fan coil heating and cooling units. Specifically the thermostat uses relays to actuate external devices such as heating and cooling equipment, fans and dampers. The use of relays permits control voltages for these external devices to be different (e.g. 24 VAC, 208-230 VAC or 277 VAC).

Extended clock termostat

Abstract: An electronically controlled thermostat for controlling HVAC equipment (26) has an emergency power configuration which only provides long term emergency power to a real time clock (38). All other components of the thermostat, e.g. the microprocessor (20), function only for a limited period of time following a power outage. Emergency power to the other components is monitored during power outage with appropriate action being taken to assure that control information has been stored in nonvolatile memory (32) before emergency power deteriorates to a critical level.

Heating and cooling system with variable capacity compressor

Abstract: Compressor discharge temperature, ambient outdoor air temperature and thermal load are used as control parameters for controlling the expansion valve setting and the indoor fan speed. In a variable capacity system the thermal load parameter also controls the compressor capacity. Thermal load is measured by an integrating procedure that increments or decrements an accumulated demand counter value used as an indication of thermal load on the system. The counter value is incremented and decremented based on the room temperature and thermostat setpoint. These same parameters are also used in the overcharge/undercharge diagnostic system.

Thermostats for molecular fluids undergoing shear flow: Application to liquid chlorine

Abstract: In this article we show that atomic thermostats which have been used in the past for nonequilibrium molecular dynamics (NEMD) simulations of molecular fluids were incorrectly formulated. The error stems from an incorrect assumption made about the form of the streaming angular velocity. This assumption is incorrect even in the linear regime. One spurious effect of this atomic thermostat is the generation of a nonsymmetric pressure tensor. We outline a general method, based on a variational principle, for calculating the position and orientation dependent streaming velocity. Using this streaming velocity we develop an atomic thermostat for molecular fluids which does not bias the positional or orientational distribution functions for the fluid. The new atomic thermostat is validated in NEMD simulations of liquid chlorine undergoing planar Couette flow.

Two terminal line voltage thermostat

Abstract: A two terminal line voltage thermostat includes a switch (22) which effectively connects line voltage to a heater load. The entire process is controlled by an integrated circuit micro-controller (10) which is powered by a rectified voltage from a transformer secondary connected to a primary which is in series with the heater load. Backup battery (11) power is provided to maintain limited functions of the micro-controller in the event of overall power loss. The micro-controller is programmed to meet the temperature sensing (18) and control requirements specific to a two terminal electric baseboard heating installation.

Thermostat having short circuit protection

Abstract: An electronic thermostat having a short circuit protection feature has a controller which sends control signals to circuitry used for activating and deactivating a system for conditioning air. Short circuit protection circuitry monitors the circuitry within the thermostat and indicates to the controller when a short circuit has occurred. When a short circuit is detected, the controller sets its control signal to deactivate the system for conditioning air for a predetermined period of time.

Methods and apparatus for converting a manually operable refrigeration unit to remote operation

Abstract: Methods and apparatus for converting a refrigeration unit having a manually controlled thermostat to remote operation via a data logger, without replacing the manually controlled thermostat. A set point temperature selector associated with the thermostat is fixed at a predetermined value, and a resistance temperature detector (RTD), which is normally connected to a temperature input of the thermostat, is disconnected. A set point temperature for a space conditioned by the refrigeration unit is selected via the data logger. The data logger monitors the temperature of the conditioned space, compares the temperature of the conditioned space with the set point temperature selected via the data logger, and determines an operating mode for the refrigeration unit which will cause the temperature of the conditioned space to be maintained in a predetermined range relative to the set point temperature selected via the data logger. A potentiometer is connected between the data logger and the temperature input of the thermostat. The data logger adjusts the resistance of the potentiometer to correspond to a temperature of the RTD, which, relative to the predetermined set point temperature fixed on the set point temperature selector associated with the thermostat, will cause the thermostat to implement the operating mode determined by the data logger.

Liquid heater assembly with a pair temperature controlled electric heating elements and a coiled tube therebetween

Abstract: A liquid heater assembly including a heater body having therein a coiled tube for passing liquids, a pair of heating elements, a thermistor, a thermostat, and a backup thermostat. Liquid enters the coiled liquid tube at an inlet end and exits the coiled liquid tube at an outlet end. The coiled liquid tube is positioned within the heater body between the pair of heating elements. The outlet end extends below a planar surface of the heater body. The thermistor detects the temperature changes of the heater body. The resistance of the thermistor is used to regulate the supply of power to the heating elements. The thermostat and the backup thermostat are connected in series between the power source and the heating elements to provide a safety shutoff when the heater body reaches a predetermined overheat temperature. The heater body is maintained at a predetermined temperature by regulating the electrical current to the heating elements. A receptacle can be placed in close proximity below the outlet end to minimize the air gap between the two parts. Liquid passing through the heater assembly can be delivered at a precise temperature to the receptacle below the heater assembly.

Air distribution fan recycling control

Abstract: An system for controlling the operation of the circulating fan of a closed central air conditioning(CAC) system is disclosed. The system periodically activates and deactivates only the circulating fan after a preselected delay time from the normal running of the cooling and heating modes of the CAC system. The preselected delay time is adjustable based on non thermostat parameters and include parameters such as room volume size to be ventilated and the number of occupants in the room. The control can periodically distribute and mix ventilation air or spot-conditioned (humidified, de-humidified, or cleaned) air while the CAC system is not running in the heating, cooling or constant fan modes. The cooling and heating modes of the CAC system operate independently of the fan recycling control.

Integrated controller for commercial vehicle air conditioning system

Abstract: An Integrated controller for a commercial vehicle air conditioning system according to the present invention includes a central control unit in communication with a high-pressure switch or sensor, a low-pressure switch or sensor, and an evaporator thermostat. The central control unit includes outputs that control the air conditioning system compressor and fan according to the conditions detected by the high pressure switcher sensor, the low pressure switch or sensor, and the evaporator thermostat.

Direct digital control thermostat

Abstract: An electronic digital thermostat is disclosed which is capable of use in a pneumatically controlled temperature control system of the type which has a pneumatic supply line which extends to various components of the control system and wherein the control elements of the system are controlled by varying the control pressure that is communicated to such elements. The thermostat is capable of operating in a LAN system environment, and can be retrofitted into unit ventilators and the like as a substitute for a conventional pneumatic thermostat. The thermostat has a processing means that enables sophisticated control to be achieved.

Controlled setpoint recovery

Abstract: A process is disclosed for controlling the operative setpoint of a thermostat during transition from a currently scheduled setpoint temperature to the next scheduled setpoint temperature. The operative setpoint is changed by small amounts at calculated time intervals. The time intervals are a function of the transition periods allocated for different types of systems for air conditioning air that may be operatively connected to the thermostat as well as the difference between the currently scheduled setpoint temperature and the next scheduled setpoint temperature.

Security system with HVAC fault reporting

Abstract: The performance of an HVAC system in a building is monitored by connecting a thermostat to an alarm system which is equipped to provide notification of alarm conditions through telecommunication or other direct means to some responsible entity. The alarm system access to telecommunications is employed to forward indicators of HVAC fault to predetermined offsite locations from where corrective action can be provided. The system includes a presumed fault condition processor which employs data from the thermostat to indicate to the alarm system that notification should take place.

Thermostat controlled cooler for a CPU

Abstract: A thermostat controlled cooler is described which includes a supporting frame attached to a CPU. A heat exchanger is also attached to the supporting frame. This heat exchanger includes a plurality of heat exchange fins. A heat actuating cooling chip is sandwiched between the CPU and the heat exchanger, and an electrical cooling fan is disposed above the heat exchange fins of the heat exchanger. A control circuit is attached to a side of the electrical cooling fan, and a thermostat sensor is electrically connected to the control circuit. This thermostatic sensor is inserted into a space defined by two adjacent heat exchange fins. When the temperature at the heat exchange fins exceeds a pre-setting, the cooling fan will be actuated to remove the heat by ventilation.

A combined bypass and thermostat assembly

Abstract: A cooling circuit for an internal combustion engine (11) is disclosed in which the bypass and thermostat assembly (14) includes means (38) to direct warm coolant entering the assembly (14) over a temperature sensitive portion (32) of a temperature responsive valve actuating means (31). The thermostat assembly (14) is therefore relatively unaffected by relatively colder coolant entering the assembly (14), as the temperature sensitive part (32) of the temperature responsive valve actuating means (31) remains immersed in relatively warm coolant entering the assembly (14).

Cooling system for internal combustion engine

Abstract: PURPOSE:To perfectly eliminate thermal over shooting and surge pressure which are generated at the opening time of a main valve by remarkably reducing difference between temperatures A and B CONSTITUTION:At least one small hole 17 is formed on a flange surface 15 of a bypass type thermostat 1' Under an engine cooled condition where a main valve 3 is closed and a bypass valve 2 is opened, a minute amount of cooling water passes a radiator 11 through the small hole 17 and joins a large amoung of bypass flow circulating a bypass water passage 7 for circulation Temperature difference is remarkably reduced between a water temperature A inside a thermostat housing 8 and a water temperature B in the vicinity of inside of a thermostat cap 16

Induced draft fan control for use with gas furnaces

Abstract: A gas fired furnace system (10) has a controller (14) controlling the supply of gas through a gas valve (12) and air for combustion by means of an induced air draft fan (28), ignition of the gas by means of ignitor (22), the delivery of heated air from a heat exchanger (20) by means of an air blower (34) in response to signals from a thermostat (42). A selected constant flow of air for combustion is provided by controlling the speed of the motor driving the induced motor fan (28) despite changes which may occur in back pressure. Induced draft fan motor parameters proportional to motor torque and motor speed are read on an ongoing basis and inputted to controller (14) which computes a desired voltage and compares that with referenced data stored in the controller memory and makes corrections to the speed of the induced draft fan motor to maintain the constant air flow. The motor speed and motor torque are also monitored to ensure that they are within selected limits indicative of safe operation and responsive to this input energization of a relay (KM1) is controlled to deenergize the gas valve and ignition.

Process and device for the separation and detection of components of a mixture of materials by temperature gradient gel electrophoresis

Abstract: The invention relates to a process for the separation and detection of components of a mixture of materials by temperature gradient gel electrophoresis, wherein either a spatial temperature gradient is built up by spatially separated temperature levels, or a time temperature gradient, or a temperature gradient is built up by combination of spatial and timewise temperature gradient. The temperature levels for building up the spatial temperature gradient are adjusted by controllable heating or cooling devices. To build up the time temperature gradient, the temperature level at each point of the separation path within the separation medium may be optionally adjusted time-dependently by means of controllable heating or cooling devices. There is described a device for performing the process with controllable heating or cooling devices to build up temperature gradients, a hollow body arranged between the temperature levels which contains the medium used for separation, and a thermostat jacket enclosing the hollow body.

Apparatus and method for furnace combustion control

Abstract: Furnace combustion in a multi-stage or variable input furnace is controlled by operating the furnace in a high fire mode at furnace start-up until the temperature of the products of combustion, or a temperature corresponding to the products of combustion, equals or exceeds a selected temperature. A temperature sensor, preferably a thermostat, is located downstream of the furnace zone of combustion (e.g., in a flue collector box at an outlet from the heat exchanger). The thermostat provides an indication of the products of combustion temperature and has a set point corresponding to the selected temperature. When the products of combustion temperature is less than the selected temperature, the thermostat contacts remain closed. The furnace is operated in the high fire mode while the thermostat contacts remain closed in response to a demand for heating, irrespective of whether the demand is for first stage or second stage heating. When the selected temperature is reached, the thermostat contacts open, thereby allowing the furnace to be operated in either the high fire or in a low fire mode, depending on the level of demand for heating, as indicated by an external room thermostat. By operating the furnace in the high fire mode until the products of combustion temperature reaches a selected temperature (i.e., during cold start-up operation) condensate formation is reduced and room comfort is enhanced by inhibiting air from being supplied to the room at less than a desirable temperature.

Heating system having a central control unit and radiators with presence detecting means

Abstract: The heating system includes a series of radiators (2a,2b,2c) which are controlled from the central station (1) which includes the microprocessor, a keyboard, a screen, an alarm siren and a telephone. An electricity distribution system may be used as a communications medium (3) and each radiator has a suitable modem (5). At each radiator the modem (5) is connected to the microcontroller (4) which receives information from or controls a heating circuit (6), a thermostat (7), a manual control (8), the presence detector (9), the smoke detector (10) and a radio system (11) if preferred to the electricity system. The control system may work in a heating control mode using the presence detector and allocated temperature thresholds or in an alarm mode.

Radiant electric space heater with capillary tube thermostat

Abstract: A radiant electric space heater is provided with a high heat limiting capillary tube thermostat and with a grill which is pivotally mounted so that it may be pivoted to an out-of-the-way position for cleaning. The capillary tube thermostat extends along a wire forming part of the grill and into the housing of the heater.

Comfont control by combined temperature and humidity

Abstract: A method and thermostat for controlling comfort in an area with temperature altering equipment, but no specific humidity altering equipment. An on-off thermostat which mechanically combines temperature and humidity measurements in a predetermined ratio based on a user's perception of comfort. The thermostat does not require an anticipator when used with an air conditioner in a warm and humid climate.

Hot water heating

Abstract: The hot water heating arrangement has several hydraulic interconnected heating bodies (7) in a sequence (4), each of which has a valve (8) for controlling the throughflow amt. through the heating body. The valves are formed as difference pressure regulators equipped with difference pressure theoretical value plates. The difference pressure theoretical plate is adjustable dependent upon the room temp., e.g. via a thermostat device. The difference pressure regulator comprises two throttle positions arranged one behind the other, i.e. a regulating component and an adjustment component, the regulating component being operable by a drive which has two chambers sepd. by a membrane.

Safety device, particularly for a thermostat with an immersion rod sensor.

Abstract: A safety device is described, particularly for a thermostat (1) with an immersion rod system comprising a rod (2) realized with thermoexpansible material, a low thermal dilatation rod (3), provided within said thermoexpansible rod (2), a casing (8), within which said rods (2;3) are introduced, in correspondence of a cavity or cup (7) realized in thermoconductive material, and an interruption mechanism (4) to interrupt a phase of the electric circuit, connected to said rods (2;3), said device comprising a spring element (6), a thermally inert thin disk (9), a calibration element (10) for the safety device and an element (11) for transmitting the strains of the inert disk element (9) to an interruption mechanism for both the phases of the electric circuit, said elements being introduced, in the above mentioned sequence, from the bottom to the above along said low thermal dilatation rod (3), with the calibration element (10) that is regulated in such a way to make the safety device intervening at a temperature higher than the intervention temperature of said interruption mechanism of a phase of the circuit, and said inert disk (9)element being realized with a concavity toward the bottom and having features to trip upside, reversing its concavity, following the dilatation of the thermoexpansible rod (2).

Thermostat water valve for road vehicle cooling system

Abstract: The thermostatically controlled valve (10) for use in the cooling system of a road vehicle engine has an inlet (14) for water that is directed either through a by-pass (13) or through an outlet (17) to the radiator. The valve actuator unit (18) is in the form of a temperature sensitive element (19) that expands axially against a spring (23) and is supported on a cross shaped member (38) and bracket (17). Valve discs (21,24) open or close the flow ports.

5 - Automatic control systems

Abstract: Automatic control systems, wherein a variable quantity is made to conform to a predetermined level, have been in use for several centuries; but, as with much technological development, the most rapid advances have taken place during recent years. In principle, many variables can be controlled by humans, but in practice this may be impossible, difficult, costly, or undesirable because of the need for continuous operation regardless of environment, large forces, and a fast response. The human reaction time of about 0.3 seconds is too slow for many applications. Further examples of control systems are liquid level control by ball valve, temperature control by thermostat, and surface control such as a ship's rudder or aircraft flaps by hydraulic servo. However, all types of control system can be modeled for analysis purposes, irrespective of the operating mechanism. In the 1950s, the potential of multiple loop systems was investigated, and the introduction of computers opened the way for much greater complexity in control systems. Computer control is usually applied to industrial problems in one of the three ways: supervisory control that continually adjusts the plant to optimum operation conditions, direct digital control, and hierarchy control that integrates the plants operation at every level from management decisions through to valve settings. Computer control is aided by the ability to measure and convert into electrical signals a wide range of system parameters such as temperature, pressure, speed, level, weight, flow, conductivity, and thickness. A fast rate of progress has been maintained to the present day, particularly since the introduction of microprocessors, so that only an introduction to automatic control systems can be attempted in a text of this length.