EP0989372A2 - Heizgerät - Google Patents

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Publication number
EP0989372A2
EP0989372A2 EP99115641A EP99115641A EP0989372A2 EP 0989372 A2 EP0989372 A2 EP 0989372A2 EP 99115641 A EP99115641 A EP 99115641A EP 99115641 A EP99115641 A EP 99115641A EP 0989372 A2 EP0989372 A2 EP 0989372A2
Authority
EP
European Patent Office
Prior art keywords
temperature
water
primary
pump
rate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99115641A
Other languages
English (en)
French (fr)
Other versions
EP0989372A3 (de
Inventor
Santokh Singh Gataora
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gledhill Water Storage Ltd
Original Assignee
Gledhill Water Storage Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gledhill Water Storage Ltd filed Critical Gledhill Water Storage Ltd
Publication of EP0989372A2 publication Critical patent/EP0989372A2/de
Publication of EP0989372A3 publication Critical patent/EP0989372A3/de
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D19/00—Details
    • F24D19/10—Arrangement or mounting of control or safety devices
    • F24D19/1006—Arrangement or mounting of control or safety devices for water heating systems
    • F24D19/1066—Arrangement or mounting of control or safety devices for water heating systems for the combination of central heating and domestic hot water
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D11/00—Central heating systems using heat accumulated in storage masses

Definitions

  • This invention relates to heating apparatus for the heating of a fluid (herein the secondary fluid) by means of another, hot fluid (the primary fluid) by heat exchange.
  • both fluids are water, but the invention is not to be considered as being limited to this medium, as other liquids could be used, and the liquids could be different and also gases or gas and liquid combinations could be used.
  • the main use of the invention is the control of the heating of secondary water by means of primary hot water, the further description given herein will be limited to this medium, but the wider application of the invention should be borne in mind.
  • a main application of heating of water by heat exchange is in the heating of domestic hot water which is used for washing purposes.
  • This water is in fact referred to as secondary water in domestic water heating systems and the water which is used for space heating by way of central heating radiators, is referred to as primary water.
  • the primary water is heated by means of a boiler or immersion heater.
  • thermal storage a body of water, supplied from the mains, is heated by the boiler or immersion heater and forms a thermal store. The heating takes place on the basis of supplying the heat to the store depending upon the residual heat stored, and not depending on instantaneous conditions of demand of the space heating and the hot water consumption.
  • the boiler or immersion heater may be adding heat to the store in the evening or during the night when there is no demand from the space heating or for hot water, and equally, the boiler may not necessarily fire when the space heating is switched on (either manually or under thermostat control) or when someone in the house opens a hot water tap.
  • the store heat supply capacity will reduce to such an extent that the boiler will fire adding heat to said store. It is possible to control the addition of heat so that it will take place during or mainly during off peak periods.
  • the present invention has particular application to any installation in which the primary water is circulated through a heat exchanger.
  • the heat exchanger is external to the storage tank which holds the store water.
  • the secondary water also passes through this exchanger, but (usually) in the opposite direction from the primary water so that the primary water gives up its heat to the secondary water.
  • the primary water is heated on demand.
  • the cold water flows from the mains through the heat exchanger (to receive heat) and then issues from the tap.
  • the supply of heat to the heat exchanger is by pumping hot primary water from the store through the heat exchanger and back to the store by means of a primary pump, the primary water giving up heat to the secondary water in the process.
  • the pump is caused to operate in that when the secondary water starts to flow, a flow switch in the pipe which carries the secondary water, is actuated, and this in turn starts the primary pump.
  • the temperature of the secondary water issuing from the heat exchanger is monitored and this monitoring is used to control the operation of the primary pump, to ensure that the temperature of the secondary water does not become too great or too small.
  • the switch is an expensive item of the system.
  • a further disadvantage of the flow switch is that in general such switches have predetermined operating limits. Therefore, the flow switch will not actuate the primary pump if the flow of the secondary fluid is below a predetermined level, and henceforth heated secondary fluid will not be available. At secondary fluid flow rates greater than that detectable by the flow switch, the flow switch may be damaged and the resulting pressure loss may be unacceptable.
  • a heat exchange system wherein the primary fluid is circulated by means of a pump through a heat exchanger through which secondary fluid is also circulated, and including sensing means for controlling the rate of heat supplied to the heat exchanger via the primary fluid, characterised in that the sensing means comprises a temperature sensor means which is arranged to sense the rate of change of temperature of the primary and/or secondary fluid issuing from the heat exchanger.
  • the temperature sensor means is preferably electronic in nature.
  • the temperature sensor means is arranged to sense at least the rate of change of temperature of the secondary fluid issuing from the heat exchanger.
  • the sensing of the rate of change of the temperature of the secondary and/or the primary fluid may be by measuring the temperature of the fluid at intervals, say half a second for example, and comparing each reading with the previous one or preferably two, in order to avoid the detecting of spurious temperature spikes
  • the system can distinguish the condition which represents the flow of secondary and/or primary fluid, from other general operational conditions of the system.
  • the temperature sensing means is adapted to sense the rate of change of temperature of both the secondary and primary fluid.
  • the temperature condition of the primary and secondary water can be accurately distinguished from the other conditions which might affect the absolute temperature of the secondary and/or primary fluid.
  • the primary fluid and the secondary fluid are preferably the primary and secondary water of a domestic thermal storage water heating system.
  • the temperature sensor means of the secondary hot water may be arranged to detect the temperature of the hot secondary water issuing from the heat exchanger.
  • the sensing control system provides that the temperature of the secondary water is being sensed at a frequency even if there is no water flow. As long as there is no rate of change of temperature of the secondary water, the pump is off. When a tap is opened and the secondary water starts to flow, its temperature will start to fall, and its rate of fall is detected. If that rate of fall is within operating limits, the pump is switched on and heat is supplied via the resulting flow of the primary water through the heat exchanger.
  • the pump is controlled (regulated) in the preferred arrangement, by the rate of change of the temperature of the primary water, with the objective of keeping the issuing hot secondary water at a pre set temperature, for example 55°C.
  • This regulation may comprise increasing or decreasing the speed of and/or stopping and starting the pump.
  • the control system also has a high temperature fails safe control, which is that if the temperature of the secondary water reaches a pre set high, for example 72°C, the pump is again switched off.
  • the temperature sensor means preferably also includes a temperature sensor in the primary side which repeatedly senses the temperature of the primary water issuing from the heat exchanger, at the same or at a different frequency as that used for the secondary sensor.
  • the main function of the primary sensor is to regulate the pump, as described above, at a first rate of change of the temperature of the issuing primary water.
  • the primary sensor also serves to switch off the pump when the primary water temperature starts to rise at a certain, different rate, showing that the flow of secondary water has been terminated, for example by the closing of the tap. This sensor in normal operation will switch down the pump before the secondary sensor does so due to a high temperature in the secondary side.
  • the primary sensor is also arranged to switch off the pump should the issuing primary water reach a pre set maximum, for example 45°C, to avoid overheating for any cause.
  • the control system may be such that if the primary temperature sensor senses a low threshold temperature, for example 35°C, the primary pump is switched on regardless of what information is being supplied from the secondary sensor.
  • the two sensors therefore work in tandem, providing excellent control and enabling the elimination of the conventional flow switch.
  • reference 10 indicates a thermal storage tank which contains a body of primary water which is heated by means of a boiler 12. To effect this heating, the water is circulated from the boiler through pipe 14 by means of the boiler pump 16. The pump draws the water from the store 10 and delivers it to boiler 12. From the boiler 12, the heated water is returned to the store via the pipe 18. Heating of the water in the store is carried out under the control of a pair of store thermostats 20 and 22 of which 20 is a limiting thermostat and controls the maximum store temperature, whilst the thermostat 22 serves to control the temperature of the store accurately to 82°C, plus or minus 3°C.
  • the device 24 is linked to the thermostats 20 and 22 and also to the pump 16, so that the device 24 or the thermostat 20 or 22 by detecting an appropriate temperature can cause the pump 16 to stop.
  • a twenty litre expansion vessel 26 which serves to accommodate expansion of the water in the tank 10.
  • the apparatus illustrated is an integrated thermal storage system in that the water in the tank 10 serves to heat the dwelling in which the apparatus is located, and to supply the heat for the secondary water which is connected at the dwelling taps and showers.
  • the water in the tank 10 is circulated through pipe 28 via a central heating pump 30.
  • the pipe is connected to the appropriate number of radiators 32.
  • a plate heat exchanger 33 For the heating of the secondary water, a plate heat exchanger 33 is used.
  • a circulating pump 34 serves to pass water from the tank 10 through line 35 and to return it to the tank 10 via line 36.
  • the secondary water is supplied from the mains via line 38 and it passes through the heat exchanger in contra flow to the primary water from the tank 10.
  • the heated secondary water emerges on line 40, which contains a sensing thermister 42, and is delivered to the dwelling consumption points.
  • the line 38 contains a flow switch 44 and electrical control lines 46 and 48 connect the sensor 42 and the flow switch 44 to a speed controller 49 which in turn controls the speed of the pump 34 via electrical control line 51.
  • circuit may also include an integral or external clock and room thermostat; these items are indicated generally by the reference 50.
  • the boiler (or in an alternative arrangement electric immersion heaters), under thermostatic control, supplies heat to the store by circulating water from the boiler through the tank 10, in known manner.
  • the heat is supplied depending upon the condition of the store 10, and not upon the instantaneous demand for space heating or hot water.
  • the room thermostat and/or clock 50 dictates when the space heating circuit is operational, and the opening of a hot water dispensing point i.e. the opening of a tap, dictates when the heat exchanger 33 is operational.
  • the arrangement provides that there is control of the pump 34 when there is a demand for hot water at say a tap. This will be detected by the actuation of the flow switch 44, which causes starting of the pump 34 to circulate hot water through the heat exchanger 33.
  • the pump speed control 49 controls the speed of the pump depending upon how much the temperature sensed by sensor 42 deviates from a predetermined level.
  • the flow switch is a problem as regards effective functioning, and cost, and the present invention provides a means whereby, by the sensing of temperature rate of change, the flow switch need not be used.
  • Fig. 2 The embodiment of the invention shown in Fig. 2 is an arrangement similar to Fig. 1, except that the flow switch as been eliminated. Similar reference numerals have been used to designate similar parts.
  • the supply line 38 passes directly to the heat exchanger 33, and there is no flow switch as in the apparatus of Fig. 1.
  • the sensor 42 is connected to controlling logic in the form of a microprocessor 43, and the sensor 42 is sensed at regular intervals, for example half a second whereby the rate of change temperature of the secondary water issuing from the heat exchanger on line 40 is constantly monitored.
  • the pump 34 is started, for example by virtue of a signal from the microprocessor on line 45.
  • the control of the apparatus is by the microprocessor 43 in the manner explained herein, in that when the pump is running, its speed is controlled by a primary sensor 47 in the line 36, which is sensed at a frequency to detect the rate of change of the primary water issuing from the heat exchanger 33. Depending upon that rate of change, so the speed of the pump 34 is controlled by the processor 43 so as to maintain a pre set temperature of the water issuing from the taps, again as explained herein.
  • An operational condition of the apparatus is indicated by the graph of Fig.3.
  • temperature detected by sensor 42 against time is indicated.
  • period 1 it is assumed that there is no demand for hot water, but that the water in pipe 40 at the sensor is still hot (the system is set up to ensure that the temperature of the water in the primary at sensor 47 is at a pre set minimum).
  • the temperature starts to drop with natural heat loss, and the temperature drifts downwards at a slow rate. Detection of this slow rate of change will not cause the pump 34 to start.
  • Period 2 however indicates that a tap has been turned on, and secondary water starts to flow out of line 40.
  • the temperature of the water sensed by the sensor 42 starts to drop at a higher rate, and this is detected by the sensor 42, and/or the control logic, which in turn causes the pump to switch on to add heat to the secondary water, whose temperature will start to rise.
  • the control of the pump speed to maintain a pre set temperature of the water issuing from the tap is under the detection of the rate of change of the temperature of the primary water by sensor 47.
  • the flowing secondary water provides a temperature rate of change, and so by detecting this characteristic, the flow switch can be eliminated.
  • the sensors 42 and 47 in conjunction with the microprocessor also provide the additional control functions mentioned herein.
  • the boiler 100 supplies the heat to the primary water, which is circulated by the pump 101.
  • the primary water is heated on demand, and is circulated by pump 101 either directly to the central heating radiators 102, or to the heat exchanger 104, when there is a demand at the tap (line 106).
  • Normally the demand at the tap has priority, and normally a flow switch 108 detects when the demand is made.
  • the flow switch can be eliminated in the same manner as it is eliminated in the thermal storage embodiment, with the same effect.
  • the same control system can be used.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Steam Or Hot-Water Central Heating Systems (AREA)
  • Domestic Hot-Water Supply Systems And Details Of Heating Systems (AREA)
EP99115641A 1998-09-24 1999-08-07 Heizgerät Withdrawn EP0989372A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9820673.3A GB9820673D0 (en) 1998-09-24 1998-09-24 Improvements relating to heating apparatus
GB9820673 1998-09-24

Publications (2)

Publication Number Publication Date
EP0989372A2 true EP0989372A2 (de) 2000-03-29
EP0989372A3 EP0989372A3 (de) 2000-04-19

Family

ID=10839299

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99115641A Withdrawn EP0989372A3 (de) 1998-09-24 1999-08-07 Heizgerät

Country Status (2)

Country Link
EP (1) EP0989372A3 (de)
GB (1) GB9820673D0 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2493222A (en) * 2011-07-27 2013-01-30 Thermal Integration Ltd Water heating system for heating mains water using a thermal store
CN104930576A (zh) * 2015-06-29 2015-09-23 北京合利能科技有限公司 高稳防腐成套供热系统
GB2531117A (en) * 2014-07-28 2016-04-13 St John Spencer Cave Piers Liquid heating appliances

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0807790A2 (de) * 1996-05-15 1997-11-19 SOLVIS Solarsysteme GmbH Anordnung und Verfahren zur Bereitstellung von warmem Brauchwasser

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0807790A2 (de) * 1996-05-15 1997-11-19 SOLVIS Solarsysteme GmbH Anordnung und Verfahren zur Bereitstellung von warmem Brauchwasser

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2493222A (en) * 2011-07-27 2013-01-30 Thermal Integration Ltd Water heating system for heating mains water using a thermal store
GB2531117A (en) * 2014-07-28 2016-04-13 St John Spencer Cave Piers Liquid heating appliances
GB2531117B (en) * 2014-07-28 2019-06-19 St John Spencer Cave Piers Liquid heating appliances
CN104930576A (zh) * 2015-06-29 2015-09-23 北京合利能科技有限公司 高稳防腐成套供热系统
CN104930576B (zh) * 2015-06-29 2018-02-09 北京合利能科技有限公司 高稳防腐成套供热系统

Also Published As

Publication number Publication date
EP0989372A3 (de) 2000-04-19
GB9820673D0 (en) 1998-11-18

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