Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H7/00—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release
  • F24H7/02—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid
  • F24H7/04—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid with forced circulation of the transfer fluid
  • F24H7/0408—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid with forced circulation of the transfer fluid using electrical energy supply
  • F24H7/0433—Storage heaters, i.e. heaters in which the energy is stored as heat in masses for subsequent release the released heat being conveyed to a transfer fluid with forced circulation of the transfer fluid using electrical energy supply the transfer medium being water
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B1/00—Methods of steam generation characterised by form of heating method
  • F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
  • F22B1/028—Steam generation using heat accumulators
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B1/00—Methods of steam generation characterised by form of heating method
  • F22B1/28—Methods of steam generation characterised by form of heating method in boilers heated electrically
  • F22B1/282—Methods of steam generation characterised by form of heating method in boilers heated electrically with water or steam circulating in tubes or ducts

Definitions

• the invention relates to boilers in which water is heated by electricity, through the medium of a core of material capable of storing heat, the core being heated by electrically powered heating elements and heat from the core being transferred to a secondary circuit in which a fluid, commonly water, is circulated, as in the case of a domestic central heating or hot water system.
• the present invention also relates to the controls for such an electric boiler.
• an electric boiler in which steam is used as the medium for transferring heat from the store to the secondary circuit.
• the general arrangement has a core of material capable of storing heat, electrically heated elements in the core, a primary heating circuit, in which water is supplied to the base of boiling tubes which pass steam upwards through the core to a heat exchanger, from which condensed water is returned to the base of the boiling tubes, losses being made up from a header tank, and a secondary heating circuit portion which passes through the heat exchanger and which is connected, in use, to a secondary heating circuit in a conventional way.
• an electric boiler will be referred to hereinafter as "an electric boiler of the kind described”.
• an electric boiler comprising a core, at least one
• a heat exchanger for transferring the stored core heat to a secondary system
• an auxiliary heater adapted to heat the secondary system directly
• control means for controlling heat supply to the core and supply of heat from the core and the auxiliary heater to the secondary system.
• control means allows electricity supply to the boiler to be accepted at different tariff rates, the control means being capable of operating the boiler differently during times of different tariff rates.
• control means operates the boiler such that a demand from the secondary system is satisfied by the core first and, if necessary, by the auxiliary heater.
• control means operates the boiler such that a demand from the secondary system is satisfied first by the auxiliary heater.
• the auxiliary heater is activated only if the core cannot satisfy the electric heat requirement. In this instance, it is preferable that a predetermined time delay must pass before the auxiliary heater can be
• the control means may also include a manual override to actuate the auxiliary heater.
• the auxiliary heater is a flow immersion heater.
• an electric boiler comprising a core, electric element means for heating the core, a heat exchanger for transferring the stored heat to a secondary system and control means for controlling charging of the core with heat and transfer of heat from the core to the secondary system, the control means operating the boiler in either a first mode in which heat supply to the core is terminated when the core temperature reaches a first temperature, and a second mode in which heat supply to the core is terminated when the core temperature reaches a second temperature, lower than the first temperature.
• the boiler preferably includes sensing means for controlling the temperature of the core.
• the core is formed from a plurality of unit cores, each unit core having at least one electric element therein.
• the electric elements may be connected in either series or parallel, or in any other suitable fashion.
• the core is formed from many unit cores, it is preferable that it is possible to heat only one or more unit core. Further, it is preferable that the maximum temperature of the or each core does not exceed 750°C.
• the maximum heat stored by the core can be varied manually to suit the users needs.
• the temperature of the secondary system can be held between two predetermined values. These predetermined values may, of course, preferably be
• the heat exchanger may include a water supply and a condensing chamber, the water being evaporated by the heat of the core and passing along pipes to condense in the condensing chamber as the heat from the steam is absorbed by the secondary system. If this type of heat exchanger is used, the transfer of stored core heat is preferably controlled by regulating the supply of water to the pipes. To ensure that a realistic temperature of the secondary system is sensed, the temperature of the
• secondary system is preferably measured only after a predetermined time delay, such as 15 seconds.
• the core is heated in two stages by the or each heater element.
• the first stage preferably being at a fast heating rate and the second stage at a slower heating rate.
• the first stage the first stage preferably being at a fast heating rate and the second stage at a slower heating rate.
• temperature of the or each heater element is preferably about 200°C above the temperature of the core and during the second stage the temperature of the or each heater element is preferably about 80oC above the core
• the temperature of the core is measured by means of a sensor mounted on an electric element.
• the electric boiler of the present invention is preferably controlled by an electronic device which may be configured by means of one or more manual switches.
• This electronic device preferably includes a clock.
• a control means for controlling the heating of and discharge from a core, the core being divided into three independent banks of bricks and heating elements, and the activation and deactivation of an auxiliary flow heater
• the control means including sensor means for sensing the input to each of the three banks of heater elements and to the flow heater, said sensor means de-activating the power supply to one of the banks of heater elements whenever power is demanded by all three banks of heater elements and the auxiliary flow heater at the same time.
• the flow heater comprises two 3kW elements
• a bank of core heater elements is not deactivated if only one of the 3kW flow elements is engaged.
• the boiler appliance never draws a load greater than 12.5kW.
• the auxiliary flow heater is activated for a preset time to preheat the secondary system before stored heat is taken from the core itself.
• efficient running of the boiler can be effected by ensuring that a large amount of stored energy is not taken from the core during a low tariff period when the core is being re-charged.
• the control means may be arranged such that during a low tariff period the core never provides heat to the secondary system, thus ensuring that the core is always fully charged at the end of the low tariff period.
• a third program setting is provided by the control means, the third setting being a frost protection mode wherein only a small amount of energy is stored in the core.
• the stored energy is utilised only to ensure that the fluid in the secondary system and boiler itself are kept sufficiently warm to prevent freezing thereof.
• this mode of operation preferably only one of the three banks of heater elements is activated, and the auxiliary flow heater manual boost is not available.
• the winter setting provided by the control means enables the core to be heated to a high temperature, in the region of 750oC, and the boost facility provided by the auxiliary flow heater is engaged automatically.
• the spring/autumn setting provided by the control means enables the core to be heated to a second temperature, lower than , the highest temperature, and the auxiliary flow heater may be activated manually to provide a boost to the heating capability of the boiler as a whole.
• a solenoid valve is provided between the heat exchanger and the header tank which opens for a predetermined time when the room thermostat is activated. By opening the solenoid valve for a short period of time, such as one minute, the pressure of cool air in the heat exchanger is removed to enable steam to enter the heat exchanger to provide heat to the secondary system.
• FIG. 1 is a schematic drawing showing the basic arrangement of the electric boiler, but with many of the details removed;
• FIG. 2 is a schematic electrical control circuit for an electric boiler according to the invention
• FIG. 3 is a schematic exploded view of certain parts of a boiler appliance according to the present invention.
• FIG. 4 is a schematic view of pipework incorporated in a boiler appliance according to the present invention.
• FIG. 5 is a perspective view of the front of a boiler appliance according to the present invention with the front panel removed to show the arrangement of the heater elements and thermostatic sensors.
• the device is required to control two prime functions: A) core temperature and B) output heating requirements.
• the user operated controls at the discretion of the purchaser, will be either an "automatic” or “manual” system, providing essentially the same requirements and the electronic control is required to accommodate both types. Via internal wiring and selection of control panel types, the individual system can be established at the time of manufacture. Additionally, it is preferred to incorporate a flow boiler and the device will be required to control its operation
• PROVISION IS REQUIRED TO ENABLE THE FLOW BOILER TO BE USED DURINS THE "OFF-PEAK” CHARGE PERIOD, WITHOUT THE CORE SERVING THE SECONDARY SYSTEM.
• the electric boiler comprises a core (2) surrounding four boiling tubes (4) which are in communication with an evaporation chamber (6).
• the boiling tubes and evaporation chamber form part of a heat exchanger which transfers heat from the core (2) to a secondary system (8). It will of course be
• the core may be of any size, and that the number of boiling tubes may vary.
• the core (2) is heated by means of electric elements (10) which pass through the core between the boiler tubes (4).
• the secondary system (8) includes an auxiliary heater (12) which provides heat directly to the system avoiding the need to use the core (2).
• the whole electric boiler, including the auxiliary heater (12), is controlled by a control unit (14).
• the control unit which is hereinafter described in more detail, has a major function of using off-peak and peak rate electrical energy most efficiently. Accordingly, the control unit (14) ensures that as little peak rate
• a manual switch (A) sets the maximum temperature of the core for use in either Spring/Autumn or Winter, depending on the stored energy required to heat the secondary system (8). For example, the Spring/Autumn setting allows the core to be heated to a maximum
• the temperature of the core is monitored by a core thermostat (B) which is mounted on an electric element (10), but alternatively may be positioned elsewhere within the core (2).
• the control unit (14) regulates the electrical energy to the electric elements (10) which may be either in parallel or in a series arrangement. Below 600°C, groups of electric elements (10) are continuously cycled by means of switch (C), and above 600°C switches (D) effect a series arrangement of the electric elements (10). This set-up provides efficient heating of the core (2) without overheating any particular electric element (10) and hence causing breakdown of that element.
• An off-peak detector relay (designated R2) is sensitive to the change from high cost electricity to low cost and back again.
• the relay R2 has one normally open single pole contact R2,1 and two normally closed single pole contacts R2,2 and R2,3. Contact R2, 1 which is normally open closes when off-peak electricity is
• R2, 1 completes part of the circuit to the auxiliary heater (12).
• the remainder of the circuit to the auxiliary heater (12) is controlled by a relay R1 which has a normally open contact R1,1. This contact R1,1 is closed when it is desirable to utilize the flow heater (12).
• a boost facility is available whereby on-peak electricity is used to supply the auxiliary heater (12).
• Switches J and K activated manually by a user provide a 1 hour or 2 hour respectively supply of electricity to auxiliary heater (12).
• an automatic boost for winter-time is provided via switch L and an overriding manual boost is activated by switch M.
• These latter two boost switches L and M are pre-empted by a delay switch N which only closes after a preset time delay during which it is ascertained whether the boost is actually necessary (i.e. whether the core can supply sufficient energy to satisfy the need of the secondary circuit).
• a switch G is triggered when contact R2,1 is closed (and hence off-peak electricity is available), thus resulting in the cancellation of the manual boost
• an L.E.D. is triggered on the control display panel.
• the L.E.D. remains energised until the cycle ends or "cancel" is initiated.
• All the manually operated boost switches can be cancelled (i.e. opened) by means of a manual switch R.
• This facility allows the user greater control over the use of on-peak electricity.
• a programmer (16) includes a clock and a series of times (preset by the user) for the activation and
• the programmer (16) sends out an activation signal when the secondary system should be hot.
• This activation signal is controlled by a room thermostat
• the secondary system water temperature is sensed by means of a thermostat (T). Hence, if the room temperature is below a predetermined value, the room thermostat is closed, and if the secondary system water temperature is also below a pre-determined value , that switch also is closed thus triggering both the auxiliary heater relay R1 and a solenoid water valve V which allows water to enter the boiling tubes (4) within the core (2).
• a short circuit is provided which overrides the secondary system water temperature sensor (T) for a predetermined time to allow the temperature of the water in the secondary system to reach an accurate value, rather than a value dictated by the close proximity of the core (2).
• switch (A) In use, switch (A) is set for either Spring/Autumn or Winter running. This dictates the temperature at which the core thermostat (B) opens. When an off-peak supply of electricity is available, switch (C) allows electricity to reach groups of
• heater elements (10) in cycles. Up to a core te ⁇ perature of 600 °C it is intended to have all elements continuously energised, but above 600°C, switches (C) and switches (D) may be activated to allow a series/ parallel arrangement and/or cycling to become operable. When the core reaches the predetermined temperature controlled by thermostat (B), the heater elements (10) are disconnected from the supply of electricity.
• auxiliary heater (12) is activated. In this instance, the relay contact R1,1 is closed and the electricity is
• the on-peak supply may be used by either selecting the one hour (switch J), the two hour (switch K), the manual override (switch M) or the automatic winter boost (switch L). When any one of these booster switches have been activated, and hence the on-peak electricity is being used, the L.E.D.(s) on the display panel is activated.
• the electric boiler is designed to store energy in the core during the off-peak time, such that the core is fully charged at the end of the off-peak period. The stored energy may then be released as dictated by the programmer (16) during the on-peak period.
• the core heat is supplied to the secondary system by way of the heat exchanger.
• An aim of the invention is for the core to provide all the energy during the on-peak period, since this heat energy is stored energy collected during the off-peak period, and for the auxiliary heater (12) to provide the required energy during the off-peak period or alternatively only after the core has exhausted its store of energy during the on-peak period. In this way, the electricity available to the heater can be used particularly efficiently.
• a boiler appliance includes a core (21) (made up of a plurality of refractory bricks (22)), insulating panels
• control means (36) and control means (36).
• the arrangement of the components is described in our co-filed PCT application mentioned earlier and will therefore not be described in detail here.
• the return pipe (38) extends from the primary heating circuit to the header tank (34).
• the top of the return pipe is above the water level in the header tank at all times so that water cannot pass from the header tank down the return pipe (38).
• the motor valve (40) is closed to prevent water entering the primary heating circuit from the header tank (34) and the solenoid valve (42) between the heat exchanger and the header tank (34) is also closed. Pressure within the primary heating circuit then forces the water/steam in the primary circuit up the return pipe (38) and into the header tank (34). No water from the header tank can pass down the return pipe (38) since the upper end of the pipe is above the water level in the header tank (34).
• the header tank (34) includes a sensor (44) to determine the water level in the tank (34) and hence when additional water should be added via the inlet (46). When the water level in the header tank (34) has fallen below a predetermined level, the sensor (44) is triggered and a light illuminates on the control panel of the boiler appliance.
• auxiliary flow heater (32) must not consume more than 3kW when all three banks of heater elements (28) in the core are activated.
• the auxiliary flow heater (32) incorporates two 3kW heating elements.
• sensor means (not shown) is included in the boiler appliance to sense the input into each of the banks of core heater elements (28) and also into each of the 3kW heater elements of the auxiliary flow heater (32).
• the sensor means senses that all of the heater elements are to be activated, e.g. when the core is being re-charged and the secondary heating circuit is being boosted by activation of the auxiliary flow heater, the sensor means automatically cuts out the supply to one of the banks of the core heater elements (28). In this way, the overall load taken by the boiler appliance is reduced from a possible 15.5kW to 12.5kW.
• the arrangement would usually be that the upper of the three blocks of core heater elements (28) would be de-activated, but other options are obviously also available. For example, rather than one of the core blocks being de-activated, one of the two flow heater elements could alternatively be de-activated.
• the header tank is made of plastics material which enables it to withstand changes in internal pressure and temperature by virtue of its suitable properties. Further, the heat exchanger is more efficient if it is made from copper rather than steel, and water can be drained from the heat exchanger more easily if the exchanger is angled slightly with the drain pipe (48) extending from its lower end.

Landscapes

• Engineering & Computer Science (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Sustainable Energy (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Heat-Pump Type And Storage Water Heaters (AREA)
• Control Of Steam Boilers And Waste-Gas Boilers (AREA)
• Central Heating Systems (AREA)

Applications Claiming Priority (8)

Publications (2)

Family

ID=27450225

Family Applications (2)

Family Applications After (1)

Country Status (4)

Families Citing this family (1)

Citations (6)

Family Cites Families (3)

• 1989
  • 1989-12-06 ES ES90900240T patent/ES2070310T3/es not_active Expired - Lifetime
  • 1989-12-06 EP EP19900900241 patent/EP0533658A1/de not_active Withdrawn
  • 1989-12-06 WO PCT/GB1989/001458 patent/WO1990006477A2/en not_active Application Discontinuation
  • 1989-12-06 DE DE68921988T patent/DE68921988T2/de not_active Expired - Fee Related
  • 1989-12-06 WO PCT/GB1989/001459 patent/WO1990006473A2/en active IP Right Grant
  • 1989-12-06 EP EP90900240A patent/EP0447438B1/de not_active Expired - Lifetime

Patent Citations (6)

Also Published As

Similar Documents

Legal Events