Abstract: A thermostat receives requests to enter into setback modes of operation whereby at least one setpoint normally used by the thermostat is to be changed at a stipulated start time for each setback mode of operation. The thermostat is operative to enter into a requested setback mode of operation at a time following the requested start time in the event there has been a delay in receiving the request to enter into a setback mode of operation. The thermostat is furthermore operative to track the time that elapses during each setback mode of operation and to report the total accumulated time that has elapsed in response to a request to do so. The thermostat is furthermore operative to set the total accumulated time to zero in response to a request to initialize the total accumulated time.

Abstract: A method is provided for managing the energy usage of an energy consuming system adapted to determine the energy of a controlled space, the energy consuming system including a plurality of operating components having on and off states and a plurality of differing noise levels when making transitions between the on and off states. The method includes determining the noise levels of the components of the energy consuming system, selecting a relatively low noise level component of the energy consuming system to provide a selected noise masking component, and causing a relatively high noise level component of the energy consuming system differing from the selected noise masking component to make a transition between on and off states. The method further includes causing the selected noise masking component to make a transition between its on and off states after the transition of high noise level component.

Abstract: A thermostat receives requests to enter into setback modes of operation whereby at least one set point normally used by the thermostat is changed. The thermostat is operative to compute the time that elapses during each setback mode of operation. The thermostat is also operative to maintain a running total of such computed times in order to respond to any request for the total accumulated time that has elapsed in the setback modes of operation. This includes computing, if necessary, the amount of time that has elapsed in a setback mode of operation occurring during a request for the total accumulated time. The thermostat is furthermore operative to set the total accumulated time to zero in response to a request to initialize the total accumulated time.

Abstract: A thermostat system for controlling activation of a temperature management system is operable in an energy-savings mode for enhancing energy savings and in a comfort mode for enhancing comfort, where the operating mode is selectable by a user. The thermostat system has operating mode control circuitry which includes (1) a manual mode control operable to cause the operating mode control circuit to switch between the energy-savings and the comfort states when pressed by the user, (2) a wireless receiver for receiving a wireless mode switching signal that causes the operating mode switching circuitry to switch between the energy-savings and the comfort states, and (3) telephone communication circuitry for receiving a telephonic mode switching signal that causes the operating mode switching circuitry to switch between the energy-savings and the comfort states. Thus, the present invention offers at least three convenient ways for the user to switch between energy-savings and comfort modes of operation.

Abstract: A thermostat receives setpoint information from a system in communication with the thermostat. The thermostat is operative to modify any locally entered setpoints by a predefined amount dictated by the setpoint information received from the system in communication with the thermostat. The thermostat is preferably operative to continually display the time remaining during which it will be under the control of the system in communication with the thermostat. This affords an occupant of the room viewing the displayed time with an opportunity to elect to either continue or to override the control by the system in communication with the thermostat at any time.

Abstract: The present invention relates an automatic adjusting control system which is able to automatically adjust an operation setting value thereof according to the air-conditioning environmental conditions and the changes of load or the requirements of users. The control system mainly includes a plurality of air-conditioners, a plurality of sensors, a central control unit which is able to compare the operation setting value with values detected by each of the sensors to produce a mating signal, and a plurality of control boxes being able to control the operation of each of the air-conditioners according to the mating signal supplied from the central control unit so as to adjust the air-conditioning effect and to save energy.

Abstract: An indoor environmental condition control and energy management system includes a plurality of inputs. A user input receives user input parameters including a desired indoor environmental condition range for at least one energy unit price point. An indoor environmental condition input receives a sensed indoor environmental condition. An energy price input receives a schedule of projected energy unit prices per time periods. A processor, coupled to the inputs, computes an environmental condition deadband range for multiple energy unit price points based on the user input parameters and controls at least one energy-consuming load device to maintain the indoor environmental condition within the computed deadband range for a then-current energy unit price point. In an embodiment, the environmental condition includes at least temperature and the at least one load device includes a heating and cooling system.

Abstract: This invention provides a novel, inexpensive, universal energy control computing accessory module for altering at programmed times the operation of existing adjunct thermal/ventilation systems. In the module, interactive programming of control timing permits the accessory to be easily adapted for different types of adjunct installations to produce timed control signals particularly adapted for control of the particular installed system. One typical mode of operation is to turn on or off cyclically the thermal/ventilation system to run at a prescribed timing duty cycle. The invention may be used for diverse utility modes of operation, such as providing periodic ventilation controls for an unattended beach vacation home or for providing semi-automatic control of installed heating or air conditioning systems during occupancy of hotel rooms, dwellings, or stations within commercial buildings, as sensed by auxiliary detection means.

Abstract: A humidity-modulated dual-setpoint temperature controller is disclosed in which the two setpoints of the temperature controller are adjusted as a function of measured humidity. Parameters other than humidity could also be used to adjust the dual setpoints of the temperature controller. The controller is particularly useful in controlling the heater element of a clothes dryer in order to improve the energy efficiency of the dryer.

Abstract: A wireless air conditioning control system is provided. A thermostat assembly measures ambient temperature in an area to which an air conditioning system provides conditioned air. It compares the measured ambient temperature with a predetermined target temperature and wirelessly transmits air conditioning request signals to an air conditioning control assembly responsively to the comparison. The thermostat assembly and the air conditioning control assembly may be automatically mated with one another so that the air conditioning control assembly responds to air conditioning request signals only from a particular thermostat assembly. Where a plurality of transmitters are present, their transmissions are staggered to avoid data collision. The control assembly includes a freeze protection mechanism to protect against freezing conditions in the absence of air conditioning request signals. A battery powered thermostat assembly is intermittently partially shut down to reduce power consumption.

Abstract: An energy management system designed to reduce the costs of electrical energy particularly applicable to service businesses such as restaurants, service stations, convenience and grocery stores and the like. The system includes controllers to sequentially and in a predetermined manner initiate operation of a plurality of loads such as appliances and other devices thereby to reduce the demand rate for electricity. A plurality of operating modes are designed for the particular loads or devices and determine the quantity of energy needed under various operating conditions, the operating modes consuming reduced power and generally being associated with a duty cycle. A capacitance bank is associated with those loads having motors to increase the power factor when the motors are under operation. A timer may automatically initiate and terminate operation of the motor and the associated capacitance bank.

Abstract: The multi-function energy management system has a plurality of predetermined operating programs stored in memory in or around a micro controller. The micro controller may be pre-set to operate a plurality of heating ventilation, air conditioning and other operating devices according to selected ones of such operating programs for maintaining the temperature in a room of a building at a desired ambient temperature condition and other loads at various operating conditions. The system has a continuously operating internal clock with a back up battery having a life span of ten years. Adjustment allowance is provided in the clock for leap years and daylight savings time. The system is capable of selectively operating the heating, ventilation, air conditioning devices and other energy consuming devices such as lighting, thermal storage heaters according to the occupancy of the room to provide a maximum saving of energy consumption.

Abstract: Wireless control of an air conditioner or space heater by a portable, easily relocatable remote thermostat combined with a control signal transmitter which is placed on a table, desk or stand near an occupant of a room or office to set the operation of a cooling or heating source in order to maintain a more uniform level of air temperature comfort in the portion of the room where the thermostat is located. A wireless control receiver responsive to the transmitted control signal is included as a portion of a plug-in adapter module that plugs directly into an AC power wall receptacle. An ordinary window air conditioner or portable space heater is then merely plugged into the adapter module which provides ON and OFF control in response to the remote thermostat. A receiver is inclusible in a fixed-location wall thermostat, enabling the portable remote thermostat to maintain control of a centralized climate control system.

Abstract: An energy saving controller for an air conditioning system comprising a temperature sensor or sensing and measuring the temperature in an area to be controlled, a memory device for storing a first set and a second set of reference temperatures, each set of reference temperatures including a heating reference temperature and a cooling reference temperature, and a controller in communication with the memory device for selecting one of the first and second sets of reference temperatures in the memory and for comparing the selected set of reference temperatures to the measured temperature of the area. The controller is adapted to select one set of reference temperatures when the area is unoccupied by a person and to select the other set of reference temperatures when the area is occupied by a person. The occupancy information is provided to the controller by an occupancy detector. A system switch is provided that communicates with the controller and selects between a heating mode, a cooling mode, and an off mode.

Abstract: An apparatus for activating climate control systems in response to the entry and/or presence of person(s) in a dwelling. An interior sensor apparatus includes a motion or thermal energy detection unit which emits a signal in response to the presence of person(s) within a room. A door entry sensor emits a signal upon entry of person(s) into the dwelling. A climate control unit, such as an air conditioner, has a default temperature setting which is activated upon the expiration of a timing sequence maintained by a timing circuit. The timing circuit is reset upon detection of persons by the motion/thermal detection unit or the door entry sensor.

Abstract: In building environmental control, primary HVAC services are supplemented to improve individual user comfort by automatically adjusting lighting levels and airflow direction mix in the individual workspace. An individual terminal unit provides these individualized supplemental services without affecting loading on the primary HVAC system. Multiple individual terminal units disposed in an open, common area communicate with one another and adjust operations in response to neighborhood conditions to improve overall system efficiency and save energy while optimizing individual user comfort.

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.

Abstract: A room access control and energy management installation controls the air conditioning of the room, such as a hotel room, in accordance with conditions of occupancy of the room. The air conditioning of the room is controlled by a controller which receives data representing a selected operating regime produced by a computer on the basis of parameters such as the time of day, the probability of imminent occupation of the room or actual occupation of the room.

Abstract: An apparatus and method for preparing an indoor environmental conditioning system for spaces, for operation. The apparatus and method are advantageously configured for use with an indoor environmental conditioning system in which the spaces are provided with an indoor environmental conditioning input and an indoor environmental conditioning sensor, both operably connected to an indoor environmental conditioning source. Each space is further provided with means for actuating the indoor environmental conditioning source. The apparatus and method enable the indoor environmental conditioning system to be placed in an initial condition such that no space can receive, and no sensor report, indoor environmental conditioning. The indoor environmental conditioning inputs are actuated one at a time, and operably linked thereafter with the indoor environmental conditioning sensor which reports a change in environmental conditioning status.

Abstract: An adjustable thermostat range limit apparatus consists of a base member having a pair of adjustable temperature limit means. The thermostat range limit apparatus is attached in the proximity of a conventional thermostat so that the adjustable temperature limit means can come into contact with the temperature control level of a conventional thermostat. These adjustable temperature limit means will provide for a restriction in the temperature range in which the temperature control lever can be set.

Abstract: A system provides a flexible control of heating, ventilation and air conditioning (HVAC) for enclosed areas. The apparatus and method of the present invention measures selected internal environmental variables in the enclosed area including data from a motion sensor indicating the occupancy status of the area for automatically controlling the operation of the HVAC system. Control settings are made to meet desired temperature and energy consumption levels. A logic algorithm and microcomputer determine humidity levels. The humidity levels are controlled to minimize the occurrence of mold and mildew. Algorithm timing strategies optimize air drying initiated by an occupancy sensor.

Abstract: This invention relates to a simplified, substantially self contained fuel savings control system for in-room air conditioner/heater units, which automatically turns off the power when the room is unoccupied. The system is typically contained in a single housing unit that may be plugged in between an in-room power line outlet and a power cord to the heater-cooler unit. The system is universal in scope, being adaptable to different kinds of thermostatically controlled systems powered from a local power line. That is achieved, in part, by letting the temperature controls built into in-room thermostatically controlled units establish the temperature and controlling the power to the in-room units by sensing room occupancy and removing power when the room is unoccupied.

Abstract: An automatic thermostat which automatically reprograms itself after a power outage without the need of a backup battery or other storage device includes a temperature sensor, a set temperature potentiometer, a setback temperature potentiometer and an ambient light sensor. The thermostat also includes a microprocessor which is responsive to signals from the temperature sensor, the set and setback temperature potentiometers and the ambient light sensor. The microprocessor controls a display which displays the set temperature, the setback temperature and the actual temperature. A power outage detector detects when there is a power outage and triggers the microprocessor to reprogram itself by rereading the signals from set temperature potentiometer and the setback temperature potentiometer. A relay is controlled by the microprocessor to selectively provide power to a heating or air conditioning unit.

Abstract: An energy saving, optoelectronic system provides a means for energizing and deenergizing electrical loads. The system includes a continuous light transmission source and a light receiving circuit that senses a light pattern and, in response, develops a first or a second output signal. The system also includes a gating circuit that receives the output signal. The gating circuit comprises a logic circuit arranged such that the receiving circuit will transmit the second output signal upon receiving a predetermined light signal. The system further includes a power switch that is open in response to an open circuit signal from the gating circuit and is closed in response to close circuit signal from the gating circuit. This system further includes a timing circuit for periodically energizing and deenergizing heating, ventilating, and air-conditioning loads.

Abstract: A wireless thermostatic control system includes a door sensor to detect when a room door is open, a transmitter associated with the door sensor to transmit signals indicating that the door sensor has been triggered, and a single thermostatic control unit for replacing a conventional thermostat which unit includes a receiver to receive the transmitted door signals, a sensor to determine whether a room is occupied in response to receipt of the transmitted signal, and two thermostatic controls, one for a room occupant and one for an energy-saving setback mode when the room is not occupied.

Abstract: An apparatus and method for controlling energy supplied to a space conditioning load and for overriding a load control operation in response to measuring certain space temperatures within a closed environment. The load control apparatus includes a control device connected to an electrical distribution network and to a space conditioning load and a temperature sensing device connected to the control device. The control device conducts a load shedding operation to control distribution of electrical energy to the space conditioning load in response to command signals supplied by a remote command center. The temperature sensing device operates to override the load shedding operation by outputting a control override signal to the control device in response to sensing certain space temperatures within the closed environment.

Abstract: The present invention is related to many space heating and cooling systems, which include central building heating and/or cooling source, such as boiler, chiller, furnace, air handling unit, etc. and which have at least one stationary room thermostat to control climate conditions in the building. It is suggested in addition to a stationary thermostat to use an extra thermostat, so called mobile thermostat, to provide flexible room air temperature control at any building location which is critical at the particular moment, including the rooms which do not have a stationary thermostats. This mobile thermostat has an authority, if it is necessary, to be override control of the stationary thermostat at any time and, therefore, to control room space heating and/or space cooling at any particular location to provide a required comfort in any room in the building.

Abstract: An apparatus and method for controlling the operation of (HVAC) equipment or other climate control equipment. The method is executed by a conventional computer with a memory storing a program. The system determines whether the space is not occupied and if the temperature drifts outside an allowed margin, then the system allows the temperature to drift to a maximum allowable margin, or to a newly determined margin, whichever is less. The newly determined margin is based upon a determination of the maximum temperature margin to which the system can drift and still drive the temperature back substantially to the use set point within a predetermined maximum recovery time. The recovery time is calculated based upon past temperature-vs.-time data stored for previous cycles of drift and drive.

Abstract: Disclosed herein is a temperature control system for multi-zone temperature control with setback control. The system includes a thermostat associated with each zone of a building, and a central control unit which communicates with each thermostat to send temperature setpoint values to each thermostat for the purpose of conserving energy and reducing energy consumption during certain times of the day. Each thermostat is associated with either a heating or cooling device, where setup temperature values are sent from the central control unit to the thermostats where cooling devices are used in place of heating devices. The thermostats are designed to operate as stand-alone units which control the temperature within a zone based upon a temperature setpoint stored at the unit. The temperature setpoint values are replaced by the higher or lower temperature setpoint values transmitted to the thermostats by the control units during setback or setup time periods.

Abstract: An environmental control system includes a plurality of electronically controlled zone controllers mounted on local VAV boxes for regulating the lighting, temperature and ventilation in a plurality of small zone areas. Each zone controller includes a timer which may be adjusted dynamically to change environmental requirements for zone occupants. A remote master computer is coupled to each local controller to provide three modes of lighting and HVAC equipment control. The inventive method of using the system includes controlling selectively individual ones of the zone controllers to provide three modes of operation an OCCUPIED mode, a STANDBY mode, and an UNOCCUPIED mode where the time period for each mode is adjustable either locally from the zone or remotely from a remote console.

Abstract: The present invention provides a system for controlling heating and cooling equipment in an energy efficient manner. The system comprises a microcontroller, a temperature sensor, a motion detector, a telecommunications interface and a control interface for the heating and cooling equipment. The system can override the thermostat control of the heating and cooling equipment and operate the equipment at a first set-back level and a second set-back level. The system will operate at the first set-back level if there is no motion for a pre-determined period. The system will revert to thermostat control if motion is detected within a second pre-determined period, otherwise the system will initiate operation at the second set-back level. The system will operate at the second set-back level until motion is detected or a control signal is received from a telephone. If thermostat control is initiated by a telephone, then the system will disable operation at the first set-back level until motion is detected.

Abstract: To save energy in hotel and motel rooms, apartments and temporarily occupied rooms generally, an apparatus for saving energy includes a temperature control circuit that overrides a thermostat for controlling an air conditioning unit in a hotel room and a switching circuit to disconnect power to lights when the room is not being occupied. The temperature control circuit maintains the temperature of the room at a higher temperature to save energy, but not so high as to return the temperature of the room to a comfortable temperature. To return power to lights and control of the air conditioning unit to the thermostat, a tag attached to a key necessary for entering the room must be inserted into a switch included with the apparatus. A delay circuit permits the person sufficient time to leave the room after removing the tag before the thermostat is overridden and power to the lights disconnected.

Abstract: The present invention relates to a means for preventing unnecessary expense in operation of a heating, ventilation and air conditioning system (HVAC) especially in areas wherein occupancy may be sporadic and where the occupants of such areas may not be personally concerned with keeping the expense of running such systems at a minimum. To accomplish this the present invention provides for at least two thermostatic controls within such area, one of such controls having fixed limits for the ambient temperature within the area while the other has variable limits therefor. The fixed limit control is locked and only accessible for adjustment by authorized personnel having the key to such lock. The variable limit control is actuated to override the fixed limit control through the operation of relay switches initiated by an infrared motion sensor unit positioned within such area.

Abstract: A Network Management Control System for a multi-space building having individual space heating and cooling units in each space that ties the individual heating and cooling units together with a central computer which allows the remote computer to interrogate and overwrite parameters set at each local heating and cooling unit.

Abstract: An electrically-powered portable space heater of the type having one or more vertically extending fin-tube heating elements disposed within an elongated housing has a selectively adjustable temperature controller responsive to a signal from an upwardly extending thermistor externally pivotally mounted on the rear of the heater housing for movement from a storage position behind the housing to an upraised operative position, thermistor also being used to supply a room temperature signal to an ambient temperature display device on the heater housing. Furthermore, the heater includes a selectively actuable energy saving feature which, when actuated, automatically reduces by 5 degrees F. after a period of one hour the temperature to which the heater has been pre-set by the operator.

Abstract: A low temperature limit for battery powered thermostats for energizing and de-energizing the heating system when the battery can no longer operate the thermostat. The thermostat comprises a battery powered thermostat control for energizing and de-energizing the heating system and a low temperature limit electrically connected in parallel with the battery powered thermostat control. The battery powered thermostat control disables a controllable switch and, thereby, the low temperature limit bimetal switch when the battery is charged. When the battery is discharged, it enables the low temperature bimetal switch limit. Thereby, when the thermostat is no longer operational, the low temperature limit energizes the heating system when the ambient temperature present on the thermostat is below a preselected temperature.

Abstract: Rooms in a building each have a heating, ventilating and air conditioning system (HVAC), a room control unit having a temperature controller, and various sensors. The control unit monitors the presence of persons in the room, determines the season, sets back the temperature in an empty room by a variable amount which the HVAC can restore in a given time, and restores the temperature to the previous user request when the user returns but to a standard temperature if the user has newly checked in. An outside hallway panel briefly displays, when interrogated by a maid, a person's presence. By monitoring maid requests, door status and maid activity, the unit indicates on a room map whether the room is being cleaned, clean, or ready to rent. By establishing the heat loss/gain (lg) factor of a room with the HVAC off and comparing it with the time to heat or cool the room, HVAC failures are determined. By comparing a room's lg factor with those of its neighbors, room environment failures are determined.

Abstract: In an exemplary embodiment of the present invention, a load operation determining portion is provided with a comparator to determine the magnitude of signals from a current sensor for parameters of each of loads, a microprocessor for comparing the signals from the determining portion with a previously set parameter and controlling a load according to the comparison result, and a load driving portion for operating a load according to the control of the microprocessor.

Abstract: A thermostat having a simple to see and use setup-setback visual indicator. One temperature control is used to set temperature while a second temperature control is used to activate the setup or setback. The second temperature control is offset from the body of the thermostat in the setup or setback mode to provide simple visual indication of the setup or setback.

Abstract: A supervisory control unit for lighting, heating and air conditioning equipment containing an occupancy sensor, a temperature limit detector, an entry delay detector and incorporating time cycle operation intended to limit the use of said equipment for the purposes of energy conservation.The unit outputs low voltage control signals that by means of external switching devices makes or interrupts the power and/or control signals normally connected to the lighting, heating and air conditioning equipment, thereby limiting the use of said equipment unless certain criteria are met.

Abstract: A control system for automatically changing the operational mode of appliances and the like, particularly environmental-affective appliances such as air conditioners, and in particular room air conditioners, as a function of the activity level prevalent in the environment being served, wherein the environmental activity level is monitored by detecting the level of ambient light and the detected light level is used to produce a signal for changing the previously-set operational parameter, e.g., room temperature. In a preferred embodiment, a lens system is utilized for focusing ambient light received at a detecting port upon a photodetector which is spaced from such port, and the resulting electrical signal is utilized in a circuit to control a heater mounted adjacent the appliance control, e.g., the air conditioner thermostat, to thereby vary the set-point in accordance with a predetermined relationship.

Abstract: The present invention provides for a self-programming temperature control system for automatically adjusting the temperature control setpoint of a heating and cooling system of a space in accordance with the present or anticipated occupancy status of the space.

Abstract: A water heater controller including hot water supply temperature sensor, a return water temperature sensor, a cold water flow sensor, a recirculation loop ambient temperature sensor, and a processor and control unit for controlling the heating of water and the circulation of water.

Abstract: This relates to a thermodynamic electronic actuator for intermittently controlling the operation of a heating and/or air conditioning system for any temperature controlled area when a door or window is left open or ajar. The actuator circuit comprises a normally-closed switch (or switches if used for more than one opening), which initiates operation of a count-up timer to interrupt the thermostat line after a predetermined period whenever a door or window is left open. To restore power, all that is required is to shut the window or door. This actuates a count-down timer that will restore the thermostat line after a predetermined period, assuming the window or door is not reopened, interrupting the countdown.

Abstract: A room temperature controlling apparatus used for an air conditioner includes a thermistor for detecting the temperature in a room, a variable resistor for setting a reference temperature for said room, a pyroelectric infrared sensor for detecting movement of a person in said room and outputting signals representative of the detection of the movement of said person, a room temperature modification circuit for modifying the room temperature detected by said thermistor based on the signals transferred from said pyroelectric infrared sensor, and a comparator for outputting a signal to control the operation of the air conditioner according to the reference temperature set by said variable resistor and the room temperature modified by said temperature modification circuit.

Abstract: A switch operator has a low friction ratchet wheel driven by a low power time programmed clock to operate the switch in one position or another depending upon the position of the ratchet wheel to operate the ratchet wheel independent of the time programmed clock. A pawl resiliently held and biased away from the ratchet wheel engages the ratchet wheel when moving in a forward direction to move it a predetermined amount. A cam member mounted adjacent the ratch wheel is engaged by the pawl to bias the pawl against a projection on the ratchet wheel when the pawl is moved forward and to bias the pawl away from the ratchet wheel upon its return movement.

Abstract: An electronic thermostat includes selectable multiple predetermined temperature programs of desired temperatures over a repetitive time cycle. A manually operable temperature program selector enables recall of a desired temperature for a particular time from a temperature program memory in accordance with the selected predetermined temperature program. This desired temperature is compared to the ambient temperature in order to generate control signals for a temperature modifying device. In the preferred embodiment, the multiple temperature programs each consist of digital signals indicative of either a normal temperature or a set-back temperature. A separate operator actuable set point device determines the normal temperature. When the normal temperature is indicated, the thermostat controls the temperature modifying load to restore the selected normal temperature.

Abstract: A hot water heater having upper and lower electric heating elements and associated thermostatic switch controls in their electric circuits is provided with an energy saving control circuit for maintaining the lower heating element deenergized at all times except when it is needed to assist the upper heating element to heat the entire contents of the hot water heater tank. The energy saving control circuit includes an energy saving switch in the electric circuit of the lower heating element. A full tank relay switch is connected in parallel with the energy saving switch and the relay coil is connected to a transformer secondary winding through a holding circuit provided by a holding relay switch the coil of which is connected to the transformer secondary through a momentary make switch. The holding relay switch serves to maintain the holding relay coil connected to the transformer secondary after the momentary make switch is opened.

Abstract: The room temperature control unit is provided with a switch for determining whether the room is vacant or occupied and if required with a switch for determining whether the room is cooled or heated, so that the room temperature is controlled while the room is vacant to be somewhat (e.g. 2.degree. C.) higher than a set temperature when the room is cooled, and somewhat (e.g. 2.degree. C.) lower than a set temperature when the room is heated. For that purpose, at least two common contacts are provided and they are connected to switch contacts in different ways so that one common contact is selected according to whether the room is vacant or occupied.

Abstract: A room temperature control system includes a transmitter-receiver unit for producing an acoustic standing wave pattern in a room and for producing a signal when that pattern is disturbed by motion in the room. A logic circuit provides timing signals and interprets a pattern disturbance signal to determine whether it evidences room occupancy. The timing and interpreting sequence is initiated by a switch which detects opening and closing of the room door. Temperature control by the room thermostat is permitted when the room is occupied and control within a wider range can be provided when it is not occupied.