EP0146264B1 - Control of a central heating system - Google Patents
Control of a central heating system Download PDFInfo
- Publication number
- EP0146264B1 EP0146264B1 EP84307939A EP84307939A EP0146264B1 EP 0146264 B1 EP0146264 B1 EP 0146264B1 EP 84307939 A EP84307939 A EP 84307939A EP 84307939 A EP84307939 A EP 84307939A EP 0146264 B1 EP0146264 B1 EP 0146264B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- thermostat
- water
- branch
- hot water
- temperature
- 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.)
- Expired
Links
- 238000010438 heat treatment Methods 0.000 title claims description 49
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 109
- 238000011144 upstream manufacturing Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 description 4
- 238000010304 firing Methods 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 241000969130 Atthis Species 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000008236 heating water Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
Images
Classifications
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- 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
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- 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
- F24H15/00—Control of fluid heaters
- F24H15/20—Control of fluid heaters characterised by control inputs
- F24H15/254—Room temperature
-
- 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
- F24H15/00—Control of fluid heaters
- F24H15/30—Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
- F24H15/305—Control of valves
- F24H15/31—Control of valves of valves having only one inlet port and one outlet port, e.g. flow rate regulating valves
-
- 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
- F24H15/00—Control of fluid heaters
- F24H15/30—Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
- F24H15/355—Control of heat-generating means in heaters
- F24H15/36—Control of heat-generating means in heaters of burners
Definitions
- This invention relates to apparatus for controlling a wet central heating system of the type in which hot water supplied by a condensing-type fuel-fired heating appliance is caused to flow either into a space heating branch or a domesic hot water branch by a flow director controlled by a priority means.
- the condensing-type fuel burning appliance usually takes the form of a fuel fired boiler, for instance, a gas boiler.
- boilers of the condensing type At least a proportion of the combustion products leaving the boiler are caused to condense by heat exchange with the water entering or leaving the boiler. This increases the overall heat content of the boiler water and therefore the overall efficiency of the system.
- condensing boilers work most efficiently when the temperature of the water with which the combustion products exchange their heat is as low as possible (preferably no more than 55°C) commensurate with satisfactory operation. In practice with present systems the temperature of the return water to the boiler may be higher than that necessary to provide efficient boiler operation.
- One method by which the efficiency of the boiler may be raised during periods when both space heating and domestic hot water are required is to provide a priority supply of boiler heated water to the branch in which reservoir water is being heated.
- the flow of the heating water to each branch is separated but heated water is supplied preferentially to the domestic hot water (DHW) branch until the temperature of the stored water has reached a preset level.
- DHW domestic hot water
- the flow of heated water is diverted to the space heating (SH) branch until the ambient temperature has reached a preset level or the temperature of the stored water has fallen below its preset level.
- SH space heating
- the heated water is then diverted to the DHW branch once more and the process continues. This procedure does at least ensure that the temperature of the return water to the boiler is relatively low (less than 70°C) during at least part of the heating cycle.
- European Patent Application No. 0059816 discloses a system of this type in which hot water supplied by a fuel-fired boiler is caused to flow either into a space heating branch or a domestic hot water branch by a flow director controlled by a priority means.
- the priority means ensures inter alia priority is given to the domestic hot water branch if the temperature of the domestic hot water falls below a lowermost threshold 8m and priority to the space heating branch if the temperature of the domestic hot water is above an uppermost threshold ⁇ M.
- the system comprises a condensing gas-fired boiler 1 which is operable to heat water to serve as a heat source system for supplying both hot water and space heating.
- the system includes a circuit 2 through which water heated by the boiler 1 is circulated by a pump 3 at least while the boiler 1 is operating.
- the circuit includes an electrically operated diverter valve 4 by means of which the heated flow water flowing in the flow pipe 5 may be diverted either into a first branch 6 or a second branch 7.
- the first branch 6 provides circulation of the heated water through space heating means in the form of radiators 8 connected in parallel in the branch 6 and by means of which heat from the heated water may be released to provide space heating.
- the second branch 7 provides circulation of the heated water through a reservoir in the form of a storage cylinder 9 to enable water stored in the cylinder 9 to be heated by a conventional calorifier 10 by heat exchange with the circulating water.
- the cylinder 9 is supplied with gravity fed cold water by a supply pipe 11 extending downwardly from a header tank 12 mounted above the cylinder 9. Stored hot water may be drawn off as required for domestic purposes by a pipe 13 via taps 14.
- the boiler 1 as is covnentional incorporates gas burners for heating the circulating water in a heat exchanger in the boiler, a gas inlet pipe for supplying gas to the burners, an ignition device such as a pilot light for igniting the gas and an electrically operated valve for controlling flow of gas through the inlet pipe to the burners.
- the boiler 1 as is the usual practice also incorporatess a thermostat which controls the gas inlet valve in response to the temperature of the water leaving the boiler 1. This determines the safe maximum water temperature in the boiler 1.
- the system also includes a cylinder thermostat 16 for controlling the temperature of the stored hot water and a room thermostat 17 for controlling the ambient temperature inside the building or dwelling from a central point.
- the system also includes a first pipe thermostat 18 for mounting on the pipework within the space heating branch 6 downstream of the radiators 8 and a second pipe thermostat 19 for mounting on the pipework in the hot water branch 7 upstream of the cylinder 9. These thermostats serve as water temperature sensors for the purposes to be described.
- the systems described also includes a conventional clock programmer 20 and control unit 21 and these too will be described in more detail subsequently.
- the programmer 20 is mains operated and as conventional can be set to switch the system on and off at certain preselected times and can be manually overridden to provide electrical power as desired.
- the programmer 20 enables the electrical power to be supplied either to the space heating (SH) line 22 or to the domestic hot water (DHW) line 23 or to both simultaneously.
- SH space heating
- DHW domestic hot water
- the circuit also comprises the cylinder, room and pipe thermostats 16, 17 and 19 respectively, relays R1 and R2, two position relay contacts R1 1 , R1" and R1 111 controlled by R1 and relay contact R2 1 controlled by R2.
- Relay R1 is activated when the cylinder thermostat 16 is closed and power is on line 23.
- the pipe thermostat 18 (for the SH branch) can switch between two positions e and f depending upon the temperature of the water at the point downstream of the radiators where it is mounted.
- the pipe thermostat 18 is in position e when the temperature of the water at the mounting point is below the preset level.
- the thermostat 18 switches to position f when the temperature at the mounting point is at or above the preset level.
- the pipe thermostat 19 (for the DHW branch) can switch between two positions g and h depending upon the temperature of the water at the point upstream of the cylinder 18where it is mounted.
- the pipe thermostat 19 is in position g when the temperature of the water at the mounting point is below the preset level.
- the thermostat 19 switches to the position h when the temperature at the mounting point is at or above the preset level.
- the preset temperature levels for the thermostats 18 and 19 are set during manufacture or installation. However the applicants have found that for efficient operation of the boiler the pipe thermostat 18 should be set to switch between positions e to f at a temperature no higher than 60°C preferably no higher than 50°C.
- the pipe thermostat 19 should be set to switch between positions g and h at a higher temperature than this but preferably a few degrees lower than the temperature at which the boiler thermostat switches the boiler off. This will prevent the boiler from cycling, that is switching on and off during a heating cycle when both hot water and space heating are demanded and thus improve the overall efficiency of operation.
- the boiler thermostat may be set to switch the boiler off at a water temperature of 82°C.
- the pipe thermostat 19 may be set to switch between positions g and h at say 79°C.
- Relay R2 is initially activated when power is on line 22, the room thermostat 17 is closed and the pipethermostat 18 is in position f. Once activated it can be maintained activated when pipe thermostat 19 is in position g irrespective of the condition of the pipe thermostat 18.
- the boiler gas inlet valve will be opened to fire the boiler if power is on line 22, the room thermostat 17 is closed and R1 1 is in position a. Alternatively, or in addition, the valve will be opened for firing if power is on line 23 and R1 1 is in position b.
- the pump 3 will operate if power is on line 22 and R1 11 is in position a. Alternatively the pump 3 will operate if power is on line 23 and the R1 11 is in position b.
- the diverter valve 4 When the diverter valve 4 is unpowered it directs the flow of water to flow into the DHW branch 7 of the heating circuit (see Figure 1) and prevents flow water from entering the SH branch 6. When however the diverter valve 4 is powered up, it directs the flow water to flow into the SH branch 6 and prevents the flow water from entering the DHW branch 7.
- the diverter valve 4 is powered up only when there is power on line 22 and either R1 111 is in position a or the room thermostat 17 is closed, R2 1 is in position c and R1 111 is in position b.
- thermostat 16 is closed ie. there is a demand both for hot water and space heating. Since the cylinder. thermostat 16 is closed, relay R1 is activated and each of the relay contacts R1 1 , R1 11 and R1 111 will be in position b.
- the boiler gas inlet valve will be receiving power from line 23 via position b, or R1 1 . If the boiler thermostat is also closed, the boiler will be firing and heating up the flow water.
- the pump will be powered up from line 23 via R1 11 and water will be circulating.
- the diverter valve 4 will be powered up as it will be receiving power from line 22 by way of the closed room thermostat 17, R2 1 in position c and R1 111 via position b. Therefore the diverter valve 4 will direct the heated flow water to flow into the SH branch to which the valve 4 will be open and no flow water will enter the domestic hot water branch.
- the space heating line 22 is switched off while the domestic hot water line 23 remains on. If the cylinder thermostat 16 is closed R1 is activated and contacts R1 1 , R1 11 and R1 111 are in position b.
- the boiler 1 receives power from line 23 via R1 1 in position b and if the boiler thermostat is closed, the boiler will fire.
- the pump will be operating as it will be receiving power from line 23 via R111 in position b.
- the diverter valve 4 will be unpowered since the SH line 22 is switched off and thus water heated by the boiler 1 will circulate only in the DHW branch.
- R1 When the cylinder thermostat 16 opens, R1 will be deactivated and R1 1 , R1" and R1 111 will move to position a.
- line 23 is switched off while line 22 is switched on.
- R1 is deactivated and the contacts R1 1 , R1" and R1 111 are in position a.
- the boiler 1 is powered up from line 22 via the room thermostat 17 and R1 1 in position a.
- the boiler 1 will fire if its thermostat is closed.
- the pump 4 will be operating since it will be powered up by line 22 via R1" in position a.
- the diverter valve 4 will also be powered up from line 22 via R1111 in position a. Thus the diverter valve 4 will be open to the SH branch.
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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)
- Fluid Mechanics (AREA)
- Steam Or Hot-Water Central Heating Systems (AREA)
Description
- This invention relates to apparatus for controlling a wet central heating system of the type in which hot water supplied by a condensing-type fuel-fired heating appliance is caused to flow either into a space heating branch or a domesic hot water branch by a flow director controlled by a priority means.
- In a conventional central heating system of the above type the condensing-type fuel burning appliance usually takes the form of a fuel fired boiler, for instance, a gas boiler.
- In boilers of the condensing type at least a proportion of the combustion products leaving the boiler are caused to condense by heat exchange with the water entering or leaving the boiler. This increases the overall heat content of the boiler water and therefore the overall efficiency of the system. However, condensing boilers work most efficiently when the temperature of the water with which the combustion products exchange their heat is as low as possible (preferably no more than 55°C) commensurate with satisfactory operation. In practice with present systems the temperature of the return water to the boiler may be higher than that necessary to provide efficient boiler operation.
- One method by which the efficiency of the boiler may be raised during periods when both space heating and domestic hot water are required is to provide a priority supply of boiler heated water to the branch in which reservoir water is being heated. In this case, the flow of the heating water to each branch is separated but heated water is supplied preferentially to the domestic hot water (DHW) branch until the temperature of the stored water has reached a preset level. Atthis point, the flow of heated water is diverted to the space heating (SH) branch until the ambient temperature has reached a preset level or the temperature of the stored water has fallen below its preset level. The heated water is then diverted to the DHW branch once more and the process continues. This procedure does at least ensure that the temperature of the return water to the boiler is relatively low (less than 70°C) during at least part of the heating cycle.
- European Patent Application No. 0059816 discloses a system of this type in which hot water supplied by a fuel-fired boiler is caused to flow either into a space heating branch or a domestic hot water branch by a flow director controlled by a priority means. The priority means ensures inter alia priority is given to the domestic hot water branch if the temperature of the domestic hot water falls below a lowermost threshold 8m and priority to the space heating branch if the temperature of the domestic hot water is above an uppermost threshold θM.
- At domestic hot water temperature lying between 8m and 8M, priority is given to the space heating branch if a room thermostat is calling for heat but to the domestic hot water branch the room thermostat is not calling for heat.
- The main disadvantage with this type of system however is that for long periods there may be no space heating at all and this is generally undesirable especially on start up of the system from cold when the requirement for space heating outweighs the requirement for hot water.
- It is therefore an object of the present invention to provide control of a central heating system of the type defined in which during periods when both space heating and domestic hot water are required the temperature of the return water to the boiler from the space heating branch is as low as possible without the disadvantage of the conventional systems.
- According therefore to the present invention there is provided apparatus for controlling a wet central heating system of the type in which hot water supplied by a condensing type fuel fired appliance is caused to flow either into a space heating branch as a priority or a domestic hot water branch as a priority by a flow director controlled by a priority means including a first thermostat which remains closed until the ambient temperature is above a preset level in which event the thermostat opens and a second thermostat which remains closed until the temperature of the water in the water reservoir is above a preset level in which event the thermoset opens, the priority means including a third thermostat which remains open until the temperature of the water in the space heating branch at a point downstream of the space heating means is above a preset level in which event the thermostat closes, a fourth thermostat which remains closed until the temperature of the water in the domestic hot water branch is above a preset level in which event the thermostat opens, the third thermostat closing at a lower temperature than the temperature at which the fourth thermostat opens and a circuit incorporating the thermostats for controlling the flow director in such a way that in the event that both the first and second thermostats are closed indicating that both space heating and domestic hot water are required, the space heating branch will normally have priority if the third thermostat is open and the domestic hot water branch will have priority if the fourth thermostat is closed and the third thermostat is closed and will retain priority if the fourth thermostat is closed during a period when the third thermostat having been closed not opens.
- An embodiment of the present invention will now be particularly described with reference to the drawings, in which:-
- Figure is a schematic diagram of a central heating system in accordance with the present invention, and
- Figure 2 is a schematic diagram of an electric circuit for controlling the system.
- Referring to Figure 1, the system comprises a condensing gas-fired
boiler 1 which is operable to heat water to serve as a heat source system for supplying both hot water and space heating. The system includes acircuit 2 through which water heated by theboiler 1 is circulated by apump 3 at least while theboiler 1 is operating. The circuit includes an electrically operateddiverter valve 4 by means of which the heated flow water flowing in theflow pipe 5 may be diverted either into afirst branch 6 or asecond branch 7. - The
first branch 6 provides circulation of the heated water through space heating means in the form ofradiators 8 connected in parallel in thebranch 6 and by means of which heat from the heated water may be released to provide space heating. - The
second branch 7 provides circulation of the heated water through a reservoir in the form of astorage cylinder 9 to enable water stored in thecylinder 9 to be heated by aconventional calorifier 10 by heat exchange with the circulating water. Thecylinder 9 is supplied with gravity fed cold water by asupply pipe 11 extending downwardly from aheader tank 12 mounted above thecylinder 9. Stored hot water may be drawn off as required for domestic purposes by apipe 13 viataps 14. - Return water from either branch returns to the
boiler 1 via thereturn pipe 15 as is the usual practice. - While not shown the
boiler 1 as is covnentional incorporates gas burners for heating the circulating water in a heat exchanger in the boiler, a gas inlet pipe for supplying gas to the burners, an ignition device such as a pilot light for igniting the gas and an electrically operated valve for controlling flow of gas through the inlet pipe to the burners. Theboiler 1 as is the usual practice also incorporatess a thermostat which controls the gas inlet valve in response to the temperature of the water leaving theboiler 1. This determines the safe maximum water temperature in theboiler 1. - As conventional the system also includes a
cylinder thermostat 16 for controlling the temperature of the stored hot water and aroom thermostat 17 for controlling the ambient temperature inside the building or dwelling from a central point. The system also includes afirst pipe thermostat 18 for mounting on the pipework within thespace heating branch 6 downstream of theradiators 8 and asecond pipe thermostat 19 for mounting on the pipework in thehot water branch 7 upstream of thecylinder 9. These thermostats serve as water temperature sensors for the purposes to be described. Finally the systems described also includes aconventional clock programmer 20 andcontrol unit 21 and these too will be described in more detail subsequently. - Referring to Figure 2 where similar components bear identical reference numerals to Figure 1, the
programmer 20 is mains operated and as conventional can be set to switch the system on and off at certain preselected times and can be manually overridden to provide electrical power as desired. Theprogrammer 20 enables the electrical power to be supplied either to the space heating (SH)line 22 or to the domestic hot water (DHW) line 23 or to both simultaneously. - These lines are provided with individual switches (not shown) to switch them on and off individually as required.
- The circuit also comprises the cylinder, room and
pipe thermostats - When R1 is deactivated the contacts R11, R1" and R1111 are in the position as shown in Figure 2. When R1 is activated the contacts R1', R1" and R1111 are in the position b.
- Relay R1 is activated when the
cylinder thermostat 16 is closed and power is on line 23. - When R2 is deactivated contact R2' is in the position c shown in Figure 2 whereas when R2 is activated R2' is in the position d.
- The pipe thermostat 18 (for the SH branch) can switch between two positions e and f depending upon the temperature of the water at the point downstream of the radiators where it is mounted. In Figure 2 the
pipe thermostat 18 is in position e when the temperature of the water at the mounting point is below the preset level. Thethermostat 18 switches to position f when the temperature at the mounting point is at or above the preset level. - The pipe thermostat 19 (for the DHW branch) can switch between two positions g and h depending upon the temperature of the water at the point upstream of the cylinder 18where it is mounted. In Figure 2 the
pipe thermostat 19 is in position g when the temperature of the water at the mounting point is below the preset level. Thethermostat 19 switches to the position h when the temperature at the mounting point is at or above the preset level. - The preset temperature levels for the
thermostats pipe thermostat 18 should be set to switch between positions e to f at a temperature no higher than 60°C preferably no higher than 50°C. Thepipe thermostat 19 should be set to switch between positions g and h at a higher temperature than this but preferably a few degrees lower than the temperature at which the boiler thermostat switches the boiler off. This will prevent the boiler from cycling, that is switching on and off during a heating cycle when both hot water and space heating are demanded and thus improve the overall efficiency of operation. The boiler thermostat may be set to switch the boiler off at a water temperature of 82°C. In this case thepipe thermostat 19 may be set to switch between positions g and h at say 79°C. Relay R2 is initially activated when power is online 22, theroom thermostat 17 is closed and thepipethermostat 18 is in position f. Once activated it can be maintained activated whenpipe thermostat 19 is in position g irrespective of the condition of thepipe thermostat 18. - Provided the boiler thermostat is closed, the boiler gas inlet valve will be opened to fire the boiler if power is on
line 22, theroom thermostat 17 is closed and R11 is in position a. Alternatively, or in addition, the valve will be opened for firing if power is on line 23 and R11 is in position b. - The
pump 3 will operate if power is online 22 and R111 is in position a. Alternatively thepump 3 will operate if power is on line 23 and the R111 is in position b. - When the
diverter valve 4 is unpowered it directs the flow of water to flow into theDHW branch 7 of the heating circuit (see Figure 1) and prevents flow water from entering theSH branch 6. When however thediverter valve 4 is powered up, it directs the flow water to flow into theSH branch 6 and prevents the flow water from entering theDHW branch 7. - The
diverter valve 4 is powered up only when there is power online 22 and either R1111 is in position a or theroom thermostat 17 is closed, R21 is in position c and R1111 is in position b. - Suppose the
clock programmer 20 is set so that both domestic hot water and space heating are required. Bothlines 22 and 23 will be switched on but if the components are in the state shown in Figure 2 with the cylinder androom thermostats 16 and .17 open, the boiler gas inlet valve will be closed, thediverter valve 4 will be unpowered and therefore open to the hot water branch but thepump 3 will be operating as it will be receiving power fromline 22 via position a of R111. Consequently water is being circulated but is not being heated by theboiler 1. - Suppose now that both the
cylinder thermostat 16 and the room,thermostat 17 are closed ie. there is a demand both for hot water and space heating. Since the cylinder.thermostat 16 is closed, relay R1 is activated and each of the relay contacts R11, R111 and R1111 will be in position b. - The boiler gas inlet valve will be receiving power from line 23 via position b, or R11. If the boiler thermostat is also closed, the boiler will be firing and heating up the flow water.
- The pump will be powered up from line 23 via R111 and water will be circulating.
- If the temperature of the water at the point in the space heating branch where the
SH pipe thermostat 18 is mounted is below the preset switching level (say 50°C) thepipe thermostat 18 will be in position e. The temperature of the water at the point in the DHW branch where theDHW pipe thermostat 19 is mounted will also be below the preset switching level (say 79°C) and thethermostat 19 will be in position g. Consequently relay R2 will not be activated and R21 will be in position c. - As a consequence the
diverter valve 4 will be powered up as it will be receiving power fromline 22 by way of theclosed room thermostat 17, R21 in position c and R1111 via position b. Therefore thediverter valve 4 will direct the heated flow water to flow into the SH branch to which thevalve 4 will be open and no flow water will enter the domestic hot water branch. - This state of affairs will continue until the temperature of the flow water in theSH branch at the downstream point where the
pipe thermostat 18 is mounted reaches its preset level. - At this stage the
pipe thermostat 18 will switch over from position e to position f. This will connect the relay R2 to line 22 (by way of thepipe thermostat 18 and the closed room thermostat 17) and relay R2 will be activated. Consequently R21 will switch from position c to position d. This will disconnect thediverter valve 4 fromline 22 which thus will be unpowered and will open to the domestic hot water branch to direct water flow around this branch. - This state of affairs will exist until the temperature of the water at the point in the SH branch where the
pipe thermostat 18 is mounted falls below its preset level and the temperature of the water at the point in the DHW branch where thepipe thermostat 19 is mounted rises to its preset level. In this event thepipe thermostat 18 will switch over from position f to position e and thepipe thermostat 19 will switch over from position g to position h. This will cause relay R2 to be deactivated since it is now no longer receiving any power fromline 22. Consequently R21 will switch over from position d to position c and thediverter valve 4 will be powered up once again fromline 22 via theclosed room thermostat 17, R21 (in position c) and R1111 in position b. Thediverter valve 4 will open once again to the SH branch to direct the flow water to flow by way of this branch. While there is a demand for hot water to heat the stored water and for space heating this process will repeat. - Should the room thermostat open at any time because the ambient temperature has risen to its preset level while the cylinder thermostat is still closed, power to the
diverter valve 4 fromline 22, via R2' and R1111 will be disconnected. Consequently thediverter valve 4 will be open to the DHW branch if not already open: Should thecylinder thermostat 16 open at any time because the temperature of the stored water has reached the preset level and theroom thermostat 17 is still closed,diverter valve 4 will receive power fromline 22 via R1111 in position a irrespective of the position of R21. Consequently thediverter valve 4 will open to the SH branch if not already open. - In the event that the temperature of the water in the
boiler 1 reaches its preset level the boiler thermostat will open, the boiler gas inlet valve will close and theboiler 1 will cease firing. However, since thepump 3 is powered continuously either from line 22 (via contact R111 in position a) or from line 23 (via contact R111 in position b) the water will continue to be circulated by way either of the DHW branch or the SH branch. - In the event that only domestic hot water is required, the
space heating line 22 is switched off while the domestic hot water line 23 remains on. If thecylinder thermostat 16 is closed R1 is activated and contacts R11, R111 and R1111 are in position b. - Consquently the
boiler 1 receives power from line 23 via R11 in position b and if the boiler thermostat is closed, the boiler will fire. - The pump will be operating as it will be receiving power from line 23 via R111 in position b.
- The
diverter valve 4 will be unpowered since theSH line 22 is switched off and thus water heated by theboiler 1 will circulate only in the DHW branch. - When the
cylinder thermostat 16 opens, R1 will be deactivated and R11, R1" and R1111 will move to position a. - Thus the
boiler 1 and thepump 4 will cease operation as they are unpowered but thediverter valve 4 will still be open to the DHW branch as this too is unpowered. - In the rare event that only space heating is selected, line 23 is switched off while
line 22 is switched on. - Therefore R1 is deactivated and the contacts R11, R1" and R1111 are in position a.
- If the
room thermostat 17 is closed theboiler 1 is powered up fromline 22 via theroom thermostat 17 and R11 in position a. Theboiler 1 will fire if its thermostat is closed. - The
pump 4 will be operating since it will be powered up byline 22 via R1" in position a. - The
diverter valve 4 will also be powered up fromline 22 via R1111 in position a. Thus thediverter valve 4 will be open to the SH branch. - Water heated by the
boiler 1 will be circulated in the SH branch. - If the
room thermostat 17 opens, power to theboiler 1 will be disconnected and it will cease operation. Thepump 3 however will continue to operate since it is receiving power fromline 22 via R1" in position a. - It will therefore be appreciated that the system operates independently of the
pipe thermostats - It is during those periods when both domestic hot water and space heating is required that the operating efficiency of the boiler is decreased. In this case, during the cycle of the operation when water is directed through the SH branch the return water temperature is no higher than the level preset by the SH pipe thermostat 18 (preferably 50°C or less). Thus the efficiency of the boiler is maintained at a high level as the return water temperature is relatively low. Furthermore the system reduces the frequency of boiler cycling, i.e. the number of times the boiler switches on and off during a heating period. This also improves the efficiency of boiler operation.
Claims (4)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8333730 | 1983-12-19 | ||
GB08333730A GB2151816B (en) | 1983-12-19 | 1983-12-19 | Control of a central heating system |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0146264A2 EP0146264A2 (en) | 1985-06-26 |
EP0146264A3 EP0146264A3 (en) | 1986-03-12 |
EP0146264B1 true EP0146264B1 (en) | 1988-05-25 |
Family
ID=10553490
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP84307939A Expired EP0146264B1 (en) | 1983-12-19 | 1984-11-15 | Control of a central heating system |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0146264B1 (en) |
DE (1) | DE3471519D1 (en) |
GB (1) | GB2151816B (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AT389584B (en) * | 1988-04-15 | 1989-12-27 | Vaillant Gmbh | HEATING SYSTEM |
FI109713B (en) * | 2001-03-05 | 2002-09-30 | Metso Paper Automation Oy | Method and apparatus for heating a roller |
GB0313350D0 (en) * | 2003-06-10 | 2003-07-16 | Hunter Roy W | Space Heaters |
ITMI20060552A1 (en) | 2006-03-24 | 2007-09-25 | Del Col Ugo Enrico | METHOD AND SYSTEM FOR CHECKING A HEATING SYSTEM |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0059816A1 (en) * | 1981-03-09 | 1982-09-15 | Societe Generale De Fonderie | Installation for central heating and domestic hot-water heating |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL7406078A (en) * | 1974-05-06 | 1975-11-10 | Burnham Europa Bv | COMBINATION SYSTEM OF SPACE HEATING WITH HOT WATER SUPPLY. |
-
1983
- 1983-12-19 GB GB08333730A patent/GB2151816B/en not_active Expired
-
1984
- 1984-11-15 EP EP84307939A patent/EP0146264B1/en not_active Expired
- 1984-11-15 DE DE8484307939T patent/DE3471519D1/en not_active Expired
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0059816A1 (en) * | 1981-03-09 | 1982-09-15 | Societe Generale De Fonderie | Installation for central heating and domestic hot-water heating |
Also Published As
Publication number | Publication date |
---|---|
EP0146264A3 (en) | 1986-03-12 |
GB8333730D0 (en) | 1984-01-25 |
EP0146264A2 (en) | 1985-06-26 |
GB2151816B (en) | 1986-10-08 |
GB2151816A (en) | 1985-07-24 |
DE3471519D1 (en) | 1988-06-30 |
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