Abstract: A method of managing excess electrical power generation can be provided by remotely controlling operation of one of at least two heating elements included in a single water heater, where the heating elements are controlled separately from one another, at a customer location in response to availability of generated electricity to the customer location.

Abstract: A cartridge type heater is provided with at least one hot wire coil (13), which has two coreless coil strands (11, 12), which extend in an insulating material (50) along the two sides of a carrier wall (14). The heater includes an insulating material that is coordinated with the internal diameter of a metal jacket (2). The hot wire ends (9, 10) are provided with terminals projecting from the same end of the metal jacket (2). The hot wire coils (11, 12) are electrically connected to one another in the area of an end edge of the carrier wall (14). This edge is located in the closed end area of the metal jacket (2) and the coils are guided by spacers (45) distributed at the longitudinal edges of the carrier wall (14). At least the terminal-side end of the dimensionally stable carrier wall (14) is provided with an attached coil holder (15, 15/1), to which the hot wire ends (9, 10) are fastened under tensile stress. This keeps the windings of the hot wire coil (13) spaced apart from each other.

Abstract: A hot melt adhesive hose assembly comprises a heater circuit wrapped around an external surface portion of the hose assembly, a temperature sensor, and an elongated thermal fuse which is likewise wrapped around an external surface portion of the hose assembly such that successive spiral turns of the thermal fuse are effectively interposed between successive spiral turns of the heater circuit. The thermal fuse may be electrically connected in series with the heater circuit so as to effectively terminate electrical power to the heater circuit as a result of the melting of the thermal fuse, or alternatively, the thermal fuse may be electrically connected in series with the temperature sensor, so as to detect abnormal temperature levels at substantially any location throughout the length of the hose assembly.

Abstract: A dry fire protection system for a water heater is provided. The water heater includes a body having an elongated hollow for holding water to be heated, an inlet opening and an outlet opening in communication with the hollow for flowing water therethrough. A heating element is coupled to the body for heating the water within the hollow. The dry fire protection system comprises a sensing element disposed in the hollow of the body for detecting the presence of water in the hollow. The sensing element is spaced from and operably connected to the heating element. The sensing element is configured to generate a voltage in response to a temperature of the sensing element. A controller is operably connected to the sensing element for monitoring the generated voltage across the sensing element. The controller is configured to prevent a supply of electrical power to the heating element as a function of the generated voltage.

Abstract: A removable cover is provided that includes a flexible elastic material forming a cover front portion and a plurality of edge portions. The plurality of edge portions are configured to be stretched over at least a portion of two or more sides of a thermostat, such that the cover may be secured onto a thermostat via the tension of the edge portions stretched over the thermostat. The cover is adapted to be placed onto the thermostat to provide protection for at least the front surface of a thermostat.

Abstract: A road finisher has a terminal box from which an electric supply circuit originates to supply electric current to at least one electric heating element for heating work components. A device for supervising the function of the at least one electric heating element includes an induction coil at the terminal box to sense current in the supply circuit and an indicator circuit, preferably of a light emitting diode, is connected to the induction coil for detecting and indicating a voltage induced in the induction coil by the current flowing in the supply circuit of a heating element. In a preferred embodiment, a cable gland is attached to the control box through which a current supply wire of the electric supply circuit passes, and an induction coil is located in the cable gland to sense the current in the supply wire.

Abstract: A redundant control circuit comprises a pair of heater circuits for heating a hot melt adhesive hose assembly to a predetermined temperature level, and a pair of temperature sensors which are used to sense the temperature of the hot melt adhesive hose assembly and to control energization of the heater circuits in order to maintain the desired temperature level. A first one of the heater circuits would initially be electrically connected to the hot melt adhesive hose assembly electrical circuitry, and in a similar manner, a first one of the temperature sensors would likewise be electrically connected to the hot melt adhesive hose assembly electrical circuitry.

Abstract: A control system suitable for use with a bathing unit system having a water receptacle is provided. The control system comprises a heating module, a power source and a controller in communication with the heating module and the power source. The power source includes an energy storage member for storing energy collected from a solar panel, and is operative for supplying power generated from solar energy to the heating module. The controller is operative for causing the power source to supply power to the heating module at least in part based on first information derived from a temperature of the water within the water receptacle and second information derived from a condition associated with the power source. The controller is further operative for selecting between a first power source and a second power source for supplying power to the heating module.

Abstract: A fusing apparatus in an image forming apparatus that heats a fusing unit by applying an induced current is provided. The flicker characteristics of the fusing apparatus are improved by gradually increasing the amount of induced current applied to the fusing unit for a predetermined amount of time so that the amount of induced current applied to the fusing unit is prevented from severely varying. The fusing apparatus comprises a fusing unit which is resistance-heated or induction-heated by applying an induced current and fuses toner onto paper using the heat. The fusing apparatus further comprises a pulse width modulation (PWM) signal generation unit which generates a PWM signal in response to the ON signal so that the amount of induced current input to the fusing unit gradually increases to a reference current.

Abstract: A fault detection system comprises a data server configured to collect parameters incoming from at least one apparatus, at least one fault-sensing module configured to generate an alarm signal if the parameter exceeds a predetermined specification, a monitoring module configured to restart the fault-sensing module if the fault-sensing module operates abnormally, and a remote controller configured to control the data server, the fault-sensing module, and the monitoring module.

Abstract: The present invention provides a control system for a bathing unit that comprises a heating module, a temperature sensing entity and a heating module controller. The heating module includes a body that defines a passage through which water can flow, that has an inner surface and an outer surface. The heating module further includes a heating device that is operative for heating the water that flows through the body. The temperature sensing entity is mounted to the outer surface of the body such that the temperature sensing entity is in thermally conductive communication with water flowing through the body. The heating module controller is operative for obtaining temperature information associated with the temperature sensing entity for detecting at least in part on the basis of the temperature information the sufficiency of water flow through the body.

Abstract: In one aspect, a cooktop heating system that include a first cooktop heating element, a second cooktop heating element, and an interface device. The system also includes a controller for selectively associating the interface device with any one or both of the first cooktop heating element and the second cooktop heating element. In another aspect, the system includes at least one cooktop heating element, a potentiometer, and controller arrangement operatively connected between the potentiometer and the at least one cooktop heating element to determine heating of the at least one cooktop heating element responsive to the input provided by the potentiometer and control power provision to the at least one cooktop heating element responsive to the determination.

Abstract: A thermal head driving method of driving thermal heads is disclosed. The method includes a step of dividing the thermal heads into plural groups, providing for each of the groups a common potential terminal, a step of using a drive circuit to drive the thermal heads of one or more of the groups, and a step of applying an operating voltage to the common potential terminal of said one or more groups driven by the drive circuit.

Abstract: A catalytic combustion type gas sensor includes a gas sensing unit 10, in which a sensing element having a heater coil embedded in a thermal conduction layer provided with an oxidation catalyst for causing a gas to be sensed to combust by contact, a compensation element having an equivalent heater coil embedded in a thermal conduction layer having no oxidation catalyst, and two resistor elements constitute a Wheatstone bridge circuit, outputs a voltage between the connection point of the sensing element and the compensation element and the connection point of the two resistor elements, as a detection signal, wherein a self-diagnosis unit is provided which diagnoses a sensor abnormality by comparing the slope of changes in voltage of the detection signal relative to changes in the voltage value of the direct-current voltage to be applied across the Wheatstone bridge circuit in an initial state and the slope of changes in voltage of the measurement value of the detection signal relative to changes in the voltag

Abstract: In an overheat protection circuit for power supply devices in the present invention, overheat protection is provided by using a Schottky barrier diode (SBD) in place of a dedicated thermosensor. The overheat protection circuit is designed to flow reverse leakage current Ir resulting from temperatures of the SBD thermally coupled with a rectifier diode to a photocoupler inside an output-voltage detecting circuit in a direct-current power supply device. Thereby, where the reverse leakage current of the SBD is increased (where temperatures of the rectifier diode are elevated due to overload), a feedback signal of the output-voltage detecting circuit is increased to decrease the output voltage, thereby the direct-current power supply device is protected from overheat.

Abstract: A sacrificial anode assembly. The sacrificial anode assembly includes a sacrificial anode, an insulator positioned around an end of the anode, an electric coupler positioned around the insulator and extending beyond the end of the anode, the electric coupler electrically isolated from the anode, a resistor having a first lead and a second lead, the first lead electrically connected to the anode and the second lead electrically connected to the electric coupler, and a cap positioned around the electric coupler, the cap electrically connected to the electric coupler and electrically isolated from the anode. The cap complete encapsulates the resistor, the first lead, and the second lead.

Abstract: A system and method for controlling one or more appliances includes a control system where one appliance is in a condition such as having operated at full capacity for a predetermined period of time, and activation signal is sent to a secondary appliance. Appliances may be linked together to control each other, so that when a second appliance is operating at full capacity a third appliance is activated and so on.

Abstract: A spa heater/control includes sensors and processors to monitor and display indicia of common failures. The heater/control includes voltage sensors and processing to measure proper power connections to the heater/control. The spa heater/control further monitors various voltages, currents, flow rates, and temperatures within the spa to provide diagnostic information which is easily obtained by a spa owner to provide to a spa dealer to reduce the time and cost of spa repairs.

Abstract: A coil of an electric motor is cooled by refrigerant. A controller for the electric motor controls a current supplied to the coil within a range less than or equal to a predetermined maximum value. A temperature detection section detects either a temperature of the coil or a temperature about the coil. When a detection temperature that is detected by the temperature detection section prior to activation of the electric motor reaches a predetermined reference temperature, a limiting section executes a limiting control to limit an upper limit value of the current supplied to the coil to a limiting value that is less than the maximum value. Accordingly, the coil of the electric motor is protected without stopping the operation of the electric compressor immediately after activation.

Abstract: A heating apparatus includes a plurality of heating means that heat a heated object, a temperature measuring means that measures temperatures of some of the plurality of heating means, a heated object information storing means that stores, in a coordinate manner, heated object identification names, target heating temperatures at the heating means, and sets of heating ratios respectively assigned to the heating means, a heating information storage means that defines a relationship between temperatures during heating of the heating means up to the target heating temperatures and heating intensities at the temperatures, a heated object identification name obtaining means that obtains one of the heated object identification names, a heated object information reading-out means that reads out one of the target heating temperatures and one of the sets of heating ratios respectively assigned to the plurality of heating means, corresponding to the heated object identification name from the heated object information st

Abstract: A heat trace system (10) is used for heating water to prevent freezing in a conduit (20) while servicing an aircraft positioned at a passenger loading bridge (52). An upstream fitting (26) is attached onto the conduit adjacent to a building structure and a downstream fitting (48) is attached onto the conduit adjacent to the cab of the passenger loading bridge. A coated retractable coiled wire disposed within the conduit and cold lead wires (46) enter through the upstream fitting and leave through the downstream fitting. A low voltage solid state power control box (56) is in communication with the cold lead attached to the coiled wire inside providing regulated electrical energy for heating the coiled wire thus preventing freezing the water within in the conduit.

Abstract: Disclosed is a quartz heater tube module in which the individual quartz heater tube proper has a first and a second coverings covered on the outer surface of the glass tube. The first covering is provided with a first electrode in electrical connection with an electrode of the quartz heater tube proper; and the second covering is provided with a second electrode in electrical connection with the other electrode of the quartz heater tube proper. In this manner, the quartz heater tube proper is securely protected by the aforesaid two coverings from breaking with an external impact. A plurality of tube propers can be connected in series or parallel by adaptive sleeves so as to form an impact resistant quartz heater tube module.

Abstract: A DC powered electric heating pad for a bed is invented comprising a plurality of carbon fiber filaments (2a) arranged in parallel for generating heat, a power distributing element (2c) for supplying power to the carbon fiber filaments (2a), a pair of metal bands (2b) for coupling both ends of the carbon fiber filaments (2a) and distributing the power supplied through the power distributing element (2c), a thermal material (2) for enveloping the carbon fiber filaments (2a) to consistently maintain the heat, and covering materials (1, 3) for protecting the thermal material (2) and the carbon fiber filaments (2a). An adapter with a bridge rectifier circuit is plugged into a regular outlet of AC as a power source for transforming to DC. The carbon fiber filament (2a) emitting the far-infrared with negative ions is designed to have excellent conductivity, durability, and ultra-light weight for protecting against harmful electrical waves by using DC.

Abstract: The heat blanket (10) comprises an operative unit (20) and a control/power supply unit (40) which can be electrically connected on one side to the power mains and on the other side to the operative unit (20). The operative unit (20) comprises a foldable sheet (21) and a linear heating element (22) distributed in the sheet (21), with a first and second conductor extending one along the other, separated by a first electrically insulating material and enclosed by a second electrically insulating material; the first and second conductor are electrically connected to the control/power supply unit (40) and have respective first terminals inside the panel which are connected together. The control/power supply unit (40) comprises a power supply group (41) for the heating element (22), intended for the connection to the electric mains, and a microprocessor configured to control the power supply for the heating element (22).

Abstract: An electronic control circuit, for use in connection a hot melt adhesive dispensing system, comprises a pair of redundant heater elements which are disposed together in a first, single heater element cartridge body disposed within a first cavity defined within an applicator head, and a pair of redundant temperature sensors which are disposed together within a second, single temperature sensor cartridge body disposed within a second cavity defined within the applicator head. The disposition of both redundant heater elements within the first, single heater element cartridge body, and the disposition of both redundant temperature sensors within the second, single temperature sensor cartridge body permits the applicator head to be reduced in size and rendered more compact, and the electrical connection of the redundant heater elements and the redundant temperature sensors to the power circuit more simplified.

Abstract: A redundant control circuit comprises a pair of heater circuits for heating a hot melt adhesive hose assembly to a predetermined temperature level, and a pair of temperature sensors which are used to sense the temperature of the hot melt adhesive hose assembly and to control energization of the heater circuits in order to maintain the desired temperature level. A first one of the heater circuits would initially be electrically connected to the hot melt adhesive hose assembly electrical circuitry, and in a similar manner, a first one of the temperature sensors would likewise be electrically connected to the hot melt adhesive hose assembly electrical circuitry.

Abstract: A self-hold motor protector (10) has an open metallic housing (12) in which a thermostatic disc (14) carrying a movable electrical contact (18) is cantilever mounted. A heater seat plate (20) is mounted in the housing in electrical and thermal relationship therewith. The heater seat plate has a seating recess (20a) in which a positive temperature coefficient resistor heating element (22) is received with one contact surface in electrical and thermal engagement with the heater seat plate. A terminal plate (26) mounts a stationary electrical contact (28) and is received over the opening of the housing but electrically isolated therefrom by a gasket (24). An electrically conductive spring (30) extends between the terminal plate and a second contact surface of the heating element.

Abstract: A circuit arrangement is provided for protecting from overheating a heating element whose resistance value is a function of its temperature. The circuit arrangement includes a power supply, a switch, and a switch control circuit, a current sensor providing a signal proportional to the current flowing through the heating element, and a first scaling device whose output provides a signal proportional to the supply voltage of the heating element. An evaluation circuit compares the difference signal determined by a first detector having an output that provides a difference signal formed from the signals of the current sensor and the first scaling device with a reference signal and the switch control circuit can be switched from a conducting state when the switch control circuit is in a first state to a non-conducting state when the switch control circuit is in a second state.

Abstract: The invention is based on a protective device for a heating unit, in particular for a cooking apparatus (10), for protecting a heating unit against a hot air flow (44). To achieve an effective cooling effect, it is proposed that the protective device for a heating unit comprises a shielding element (68), which is provided for this purpose to shield a space (46) provided for a cold cooling air flow (42) for cooling the heating unit (14) against the hot air flow (44).

Abstract: A controller for an electric article includes a voltage-stabilizing circuit for supplying voltage stable DC power, a microprocessor, a temperature-detecting circuit, a protecting circuit, a control circuit, and a switch circuit. The temperature-detecting circuit includes several comparators commonly connected to a temperature range switch. The protecting circuit includes a comparator that detects a pre-set highest heating temperature and that is connected to the voltage stable DC power and a voltage-detecting circuit of the voltage stable DC power. The comparator of the protecting circuit is further connected to a voltage-dividing end of a thermistor connected to a temperature-detecting wire. The control circuit is connected to the microprocessor and an output of the comparator of the protecting circuit. The switch circuit is connected to an output of the voltage stable DC power and the control circuit, thereby controlling conduction or cutting off DC power supply to the electric article.

Abstract: The present invention relates to a non-electromagnetic wave temperature controller for a heating cable and a method therefor, which can perform heating and temperature detection in a non-electromagnetic fashion without short-circuiting one end of the heating cable that is used in warmers, such as electric floors, electric mats and electric fomentation devices. Furthermore, the present invention relates to a temperature detection non-electromagnetic heating cable and a temperature controller, which can reduce the amount of heat and control temperature without using a separate temperature sensor when the temperature of the heating cable is controlled or an arbitrary portion of the heating cable is overheated, and can prevent a magnetic field from being generated in the heating cable without short-circuiting one end of electrical heating wires and intercept the generation of a leakage electric field.

Abstract: A cooking facilitator which is preferably portable and well suited for use as both a timer and cooking process facilitator having particular usefulness with cooking objects which have a characteristic associated with establishing a cooking time such as the weight of a turkey in the case of deep frying a turkey or the thickness of a steak in deep frying the same. A gas flow timer for shutting off an overheated or unattended cooking system is also featured.

Abstract: A power management system for managing the power supplied to a plurality of warming elements in a brewing machine, so as to conform to pre-set power safety requirements.

Abstract: A heated motorcycle handgrip is securable to a motorcycle handlebar and includes a grip housing that has a first end adapted to receive the handlebar, and a second end opposite the first end. The grip housing includes a heating element that is operable to provide a heat output, and a heater control dial is coupled to the second end of the handgrip to control the heat output of the heating element.

Abstract: A control is provided for switching on and off two heating devices of a hob forming a hotplate. In cyclic manner the continuous energy or power generation level can be adjusted by an energy control device. A temperature limiter monitors a maximum temperature via the first heating device, but not via the second heating device. The energy control device controls the first heating device directly or switches the same. The temperature limiter trips a power relay in order to switch the second heating device simultaneously with the first heating device.

Abstract: An improved control device and method is usable with flexible heating wire having a conductive core with a Negative Temperature Coefficient (NTC) layer and a helically wound heater conductor within an insulative outer sheath. The conductive core is coupled to a control circuit, a phase shift relative to the AC power supply being indicative of the temperature of the wire. The nonlinear nature of the NTC layer enhances the detection of local hot spots anywhere along the length of the wire. Precise temperature measurement is achieved by measuring the time differences between two zero crossings and the power to the heater compensates for abnormal use such as bunching of the heater wire. The control of the heater wire is particularly suitable for use with appliances such as heating pads and electric blankets.

Abstract: Apparatus and a method are provided for detecting an abnormal rise in temperature associated with a combination of a cooking utensil (10) and a cooking zone (8) of a cooking surface (4) overlying an electric heater (6). The apparatus has a first temperature-responsive device (24) is provided within the heater and adapted to monitor temperature of the cooking surface (4). A second temperature-responsive device (26) is provided within the heater and adapted to monitor temperature of the cooking utensil (10) through the cooking surface (4) to provide an electrical output as a function of temperature of the cooking utensil. Means (28) is provided for calculating first and second derivatives (D1, D2) with time of the temperature sensed by the second temperature-responsive device (26) over an operating temperature range of the heater. Means (28) is provided to determine stabilization of the first derivative (D1) within stabilizing threshold limit values.

Abstract: The oven includes a lower electrical heating element which is located below a support member. Two laterally spaced apart upper electrical heating elements are supported above the support member and the food to be cooked. An electrical system is provided for supplying electrical power to the lower electrical heating element and to the two upper electrical heating elements. A controller is provided for controlling electrical power applied to the lower heating element and to the two upper electrical heating elements. By way of a thermocouple, the controller senses the temperature in the oven and controls the lower heating element to maintain a set point temperature, i.e. 550° F., in the oven. When any of the upper heating elements is activated, and is in a broiling sequence the controller disables these upper heating elements if the temperature in the oven rises above an upper temperature level of i.e. 585° F.

Abstract: A device for carrying a heated liquid, and controlling the temperature of the heated liquid includes a liquid conveying element including a passage for carrying the heated liquid. First and second temperature sensing devices are operatively associated with the liquid conveying element to sense the temperature of the heated liquid. A controller is actively connected to the first temperature sensing device. The first temperature sensing device thereby senses the temperature of the heated liquid in the passage and conveys the temperature information or readings to the controller for use in the heater control. The second temperature sensing device is capable of being actively connected to the controller upon failure or malfunction of the first temperature sensing device.

Abstract: The present invention discloses an all disassembleable electric-heating apparatus comprising a shell, a cover, a reservoir installed inside said shell, an electric heater installed inside said reservoir and immersed in the liquid contents of said reservoir in working mode, and control elements including a control box and thermo-elements; wherein, said thermo-elements include electrical elements, said electrical elements are peripherically electric-insulated and sealed, so as to be immersed in the liquid contents of said reservoir in working mode and be taken out for cleaning after use.

Abstract: A protection circuit, configured to detect and suppress electrical pre-arcing and arcing conditions in a resistive heater wire circuit, comprises a transient voltage suppressor, signal level sensing load coupled to the output of the voltage suppressor, detection and control circuitry, and a high-speed switch or electrical gate. The control circuitry is configured to control the operation of the switch, coupled between said control circuitry and the heater wire, wherein the switch is opened in response to an electrical pre-arcing or arcing condition or a short circuit condition.

Abstract: An improved water heater for use in spas, hot tubs, pools, hydrotherapy pools, bath tubs, and similar bodies of water used indoors, outdoors, or both indoors and outdoors are used for both therapeutic and recreational purposes. The water heater uses heating element technology know as thick film on substrate comprising resistive elements bonded to the outer dry surface of a substrate to heat the substrate which in turn heats the water flowing through the heating chamber. The heater is highly efficient due to the direct contact of the wet heating surface with the water and provides a smooth seamless inner heating surface by eliminating the need to pass electrical leads into the wet region of the heater. This virtually eliminates the risk of leaks in the water heater due to bulkhead fittings. The invention further eliminates the need for a heating element to be contained in the inner wet region of a spa heater, thereby reducing the risk of corrosion.

Abstract: A controller system for a bathing installation such as a spa is disclosed. The system distributes line voltage from a line voltage service to one or more line voltage loads and controls operation of a service system for the bathing installation. The system includes a housing structure, with a controller printed circuit board mounted within the housing. The board includes a plurality of line voltage output terminals for connection to respective line voltage loads via line voltage wiring connections, a set of circuit board line voltage contact surfaces, a plurality of circuit conductors for providing circuit connections between the contact surfaces and respective ones of the line voltage from the circuit board line voltage contact surfaces to the output terminals.

Abstract: An electric heater apparatus for automobiles is disclosed. A sheathed heater (14a) constituting a heat generating member of a heater assembly (14) generates heat by power supplied from a main power supply for generating a DC high voltage through an inverter. A thermal fuse (15) has a temperature detecting element (15a) (low-melting alloy) adapted to fuse when a set temperature is reached. The temperature detecting element (15a) is connected to the power circuit of the sheathed heater (14a) through lead wires (15b, 15c). The thermal fuse (15) is arranged in such a position that the longitudinal direction of the temperature detecting element (15a) accommodated in the casing (17) is coincident with the longitudinal direction of the heater assembly 14, and mounted in surface-to-surface contact with the body (aluminum body (14c)) of the heater assembly (14). Also, the interior of the casing (17) is sealed with a material (such as cement or a silicon caulking material) higher in heat conductivity than air.

Abstract: A heat exchange assembly adapted for use in a water tank is provided. The heat exchange assembly includes a tube having end portions and a coiled portion between the end portions. A fitting is connected to at least one of the end portions of the tube. The fitting has an end configured to extend through an opening in the water tank, and a surface positioned to limit the extension of the end through the opening in the water tank. The fitting also has an opposite end defining a bore configured to receive one of the end portions of the tube and to limit the extension of the end portion of the tube into the opposite end of the fitting. The bore extends axially beyond the surface of the fitting.

Abstract: Objects of the invention relate to a detachable breakaway power supply device that can be selectively coupled to an electrical appliance. A first coupling element is carried by the appliance and a second coupling element is carried by the detachable power supply device. The power supply device is carried by a conventional power supply cord. Attractive magnetic forces between the first and second coupling elements permit selective, removable attachment and electrical contact between the appliance and the power supply device. This arrangement provides a breakaway mechanism in which disturbance of the power supply cord, e.g., by tripping, results in the separation of the power supply device from the appliance to prevent overturning of the appliance and spilling of its contents.

Abstract: A heater control is performed without problems when a normal detection of a power source frequency cannot be performed. A heater control apparatus is configured and arranged to be operable by an alternating current having one of a plurality of frequencies. The heater control apparatus detects a zero-cross point of a voltage waveform of the alternating current to be supplied to a heater so as to generate a zero-cross signal and controls an electric power supply to the heater by using the zero-cross signal as a reference. At a time of tuning a power on, the frequency of the alternating current is tentatively determined before the frequency is detected so as to control the electric power supply to the heater based on the tentatively determined frequency, and to control the electric power supply to the heater, after the frequency of the alternating current is detected, based on the detected frequency.

Abstract: A heater is provided with an accurate shutoff device that shuts off (de-energized) the heater upon detecting an over temperature condition. The heater includes a body for holding material (water) to be heated and a first heating element coupled to the body for heating material within the body. The heater also includes a temperature sensitive element coupled to the body for sensing temperature, and a shutoff switch coupled to the temperature sensitive element for shutting off the first heating element when the temperature sensitive element senses a temperature limit. The heater further includes a second heating element for heating the temperature sensitive element upon activation of the switch such that the first heating element is actively forced to remain shut off.

Abstract: An improved water heater for use in spas, hot tubs, pools, hydrotherapy pools, bath tubs, and similar bodies of water used indoors, outdoors, or both indoors and outdoors are used for both therapeutic and recreational purposes. The water heater uses heating element technology know as thick film on substrate comprising resistive elements bonded to the outer dry surface of a pipe to heat the pipe which in turn heats the water flowing therethrough. The heater is highly efficient due to the direct contact of the wet heating surface with the water and provides a smooth seamless inner heating surface by eliminating the need to pass electrical leads into the wet region of the heater. This virtually eliminates the risk of leaks in the water heater due to bulkhead fittings. The invention further eliminates the need for a heating element to be contained in the inner wet region of a spa heater, thereby reducing the risk of corrosion.

Abstract: The invention relates to a method for heating water in a domestic water heating system that comprises the steps of: (a) providing a water tank containing mw liters of water; (b) providing at least one temperature sensing unit in said water tank for sensing the temperature of the water in the tank: (c) providing a heating element in said water tank; (d) providing a control unit for activating said heating element, said control unit continuously receiving indication for the water temperature from said temperature sensing unit; (e) providing to said control unit a desired water temperature, and designating a time for using the water at said desired temperature; (f) knowing the current water temperature, the desired water temperature at said designated time, the power of the heating element, and the specific heat of the water, calculating by the control unit the heating period ?t needed for heating the water in the tank from the current temperature as measured by said temperature sensing unit, to the desired temp