GB2320966A - Control system for heating or air conditioning - Google Patents
Control system for heating or air conditioning Download PDFInfo
- Publication number
- GB2320966A GB2320966A GB9617287A GB9617287A GB2320966A GB 2320966 A GB2320966 A GB 2320966A GB 9617287 A GB9617287 A GB 9617287A GB 9617287 A GB9617287 A GB 9617287A GB 2320966 A GB2320966 A GB 2320966A
- Authority
- GB
- United Kingdom
- Prior art keywords
- temperature
- setpoint
- heating
- controlled space
- space
- 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- Withdrawn
Links
- 238000010438 heat treatment Methods 0.000 title claims abstract description 78
- 238000004378 air conditioning Methods 0.000 title claims abstract description 22
- 239000012530 fluid Substances 0.000 claims abstract description 46
- 238000012544 monitoring process Methods 0.000 claims abstract description 13
- 238000013459 approach Methods 0.000 claims abstract description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 35
- 239000004449 solid propellant Substances 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 9
- 239000004065 semiconductor Substances 0.000 claims description 3
- 238000004891 communication Methods 0.000 claims description 2
- 238000001816 cooling Methods 0.000 claims description 2
- 238000009434 installation Methods 0.000 description 11
- 230000001276 controlling effect Effects 0.000 description 10
- 239000003990 capacitor Substances 0.000 description 8
- 238000010586 diagram Methods 0.000 description 8
- 230000005540 biological transmission Effects 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000003303 reheating Methods 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000008236 heating water Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
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
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/50—Control or safety arrangements characterised by user interfaces or communication
- F24F11/52—Indication arrangements, e.g. displays
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/62—Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
-
- 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
- F24H15/10—Control of fluid heaters characterised by the purpose of the control
- F24H15/174—Supplying heated water with desired temperature or desired range of 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
- F24H15/355—Control of heat-generating means in heaters
- F24H15/36—Control of heat-generating means in heaters of burners
-
- 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
- F24H15/40—Control of fluid heaters characterised by the type of controllers
- F24H15/486—Control of fluid heaters characterised by the type of controllers using timers
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/01—Control of temperature without auxiliary power
- G05D23/02—Control of temperature without auxiliary power with sensing element expanding and contracting in response to changes of temperature
- G05D23/021—Control of temperature without auxiliary power with sensing element expanding and contracting in response to changes of temperature the sensing element being a non-metallic solid, e.g. elastomer, paste
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/1927—Control of temperature characterised by the use of electric means using a plurality of sensors
- G05D23/193—Control of temperature characterised by the use of electric means using a plurality of sensors sensing the temperaure in different places in thermal relationship with one or more spaces
- G05D23/1931—Control of temperature characterised by the use of electric means using a plurality of sensors sensing the temperaure in different places in thermal relationship with one or more spaces to control the temperature of one space
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F2110/00—Control inputs relating to air properties
- F24F2110/10—Temperature
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F2140/00—Control inputs relating to system states
- F24F2140/20—Heat-exchange fluid temperature
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Automation & Control Theory (AREA)
- General Physics & Mathematics (AREA)
- Human Computer Interaction (AREA)
- Remote Sensing (AREA)
- Fuzzy Systems (AREA)
- Mathematical Physics (AREA)
- Signal Processing (AREA)
- Steam Or Hot-Water Central Heating Systems (AREA)
Abstract
A control system for a heating or air conditioning system for a controlled space, the heating or air conditioning system supplying a heated or cooled fluid from a fluid source to the controlled space. The control system comprises a first sensor 12 for monitoring the temperature of the controlled space, and a first operator input 12 for operator selection of a desired temperature for the controlled space. A second sensor 16 monitors the temperature of the heated or cooled fluid output by the fluid source. A setpoint control 10 controls the setpoint of the fluid source such that the setpoint temperature of the heated or cooled fluid is lowered or raised as the monitored temperature of the controlled space approaches the desired temperature. In a variation, the setpoint temperature is not adjusted until the controlled space is near the desired temperature.
Description
CONTROL SYSTEM FOR HEATING AND AIR CONDITIONING
This invention relates to a control system for heating and air conditioning systems.
At present there is a lack of simple to operate accurate controls for both domestic and small commercial heating and air conditioning (H.A.C.) installations. While some larger H.A.C. installations are carefully monitored and controlled this normally involves the use of complex and expensive equipment. Further, in many cases smaller
H.A.C. operators and operators of heating only installations (including domestic homes) find the equipment currently on the market difficult to use as most require complex programming to operate correctly. This can and does result in H.A.C. installations running in an unsatisfactory manner both in terms of energy consumption and general performance.
The controls presently available to most domestic\small commercial operators usually comprise electro-mechanical thermostats, motorised valves and time clock programmers. None of these controls have the ability to adapt heating or air conditioning plant running temperatures to match the energy loading of the buildings they supply and require frequent operator adjustment to operate efficiently. Many installations exist which do not have any controls other than the thermostat on the boiler providing manual control of the setpoint temperature of the boiler, that is the temperature of the driving fluid output by the boiler which is, for example, circulated through the system radiators and domestic hot water (DHW) heating coil.
The result of poor control on any H.A.C. installation is unsatisfactory performance and low efficiency.
It is among the objectives of the present invention to obviate or mitigate the aforementioned problems.
According to a first aspect of the present invention there is provided a control system for a heating or air conditioning system for a controlled space, the heating or air conditioning system supplying a heated or cooled fluid from a fluid source to the controlled space, the control system comprising:
a first sensor for monitoring the temperature of the controlled space;
first operator input means for operator selection of a desired temperature for the controlled space;
a second sensor for monitoring the temperature of the heated or cooled fluid output by the fluid source; and
setpoint control means for controlling the setpoint of the fluid source such that the setpoint temperature of the heated or cooled fluid is lowered or raised as the monitored temperature of the controlled space approaches the desired temperature.
According to a second aspect of the present invention there is provided a method of controlling the heating or air conditioning of a controlled space utilising a heating or air conditioning system supplying a heated or cooled fluid from a fluid source to the controlled space, the method comprising:
(a) selecting a desired temperature for the controlled space;
(b) measuring the actual temperature of the desired space; and
(c) controlling the setpoint of the fluid source such that the setpoint temperature of the heated or cooled fluid is lowered or raised as the measured temperature approaches the desired temperature.
The present invention is particularly suitable for use in wet heating systems, that is systems in which heated water from a boiler is circulated through radiators at appropriate locations in a building.
Preferably, the control system, for use with a heating system, further comprises a third sensor for monitoring the temperature of water contained in a storage vessel for use as domestic hot water (DHW), second operator input means for operator selection of a desired setpoint temperature for the water, and means for controlling circulation of heated fluid from the fluid source through the storage vessel, said controlling means permitting said circulation of heated fluid when the measured temperature falls below the desired temperature. Preferably also, said means includes a motorised valve, and the valve is configured to direct a proportion of the heated fluid supply to the controlled space if the measured temperature in the controlled space is blow the desired temperature.
Preferably also, when heated fluid is being circulated through the storage vessel the setpoint control means is overridden, such that the fluid source setpoint remains relatively high to permit rapid heating of the water in the vessel.
Preferably also, the setpoint control means maintains the setpoint at a maximum or minimum temperature until the measured temperature comes within a predetermined range of the desired temperature, for example, 5 degrees centigrade below or above the desired temperature, and then lowers or raises the setpoint temperature as the measured temperature approaches the desired temperature.
Unlike presently available controls, embodiments of the present invention for use in domestic applications permit constant and accurate monitoring of the setpoint status of a domestic hot water storage vessel, the temperature of the driving fluid in a boiler and the temperature difference between the air temperature in a controlled space and an operator selected temperature. The control system uses the measured temperatures to automatically adjust the setpoint temperature of the boiler or air conditioner to accurately and efficiently reach and maintain the space and domestic hot water temperatures selected by the operator.
Preferably also, the system allows for separate timed control of space heating or cooling and domestic hot water heating via external timers or programmers.
Embodiments of the invention have the ability to control solid fuel appliances with the addition of a dedicated electro-mechanical actuator for adjusting an air inlet damper.
Embodiments of the present invention require no adjustment once installed and provide simple to use operator inputs which are similar in appearance to the majority of standard thermostat controls. Therefore the possibility of unsatisfactory performance being caused by operator error is reduced.
Preferably also, the first sensor and first operator input means are provided in a single remote unit for location in the controlled space. The second sensor and setpoint control means may be provided in a single main unit for location on the fluid source, which may take the form of a boiler.
Preferably also, one or more of the sensors are in the form of a semiconductor transducers.
In a typical heating system incorporating an embodiment of the invention, during normal operation the set point, and therefore the running temperature of the boiler, will be progressively reduced as the selected space and domestic hot water temperatures are reached, at which point the whole heating system is in a balanced condition, that is the energy input from the burner closely matches the heat loss from the space being heated. This produces more stable space temperatures. The reduction in running temperature of the heating system reduces energy losses from the boiler and its associated pipework therefore saving fuel and reducing running costs. Further, the occasions when the radiators are relatively hot and, for example, give rise to the possibility of causing burns to small children, are reduced and will only tend to occur when the system is first turned on after a prolonged shutdown. An internal adjustment means may be provided to allow the installer to select a minimum boiler temperature setpoint below which the boiler will not be allowed to cycle. This avoids cycling below required minimum operating temperature limits as specified by the manufacturer of the boiler.
According to a third aspect of the present invention there is provided a heating or air conditioning system including a control system according to the first aspect of the invention.
According to a fourth aspect of the present invention there is provided a control system for a heating system for a controlled space, the heating system including a heating medium for location in the controlled space, the control system comprising:
a first sensor for monitoring the temperature of the controlled space;
first operator input means for operator selection of a desired temperature for the controlled space;
a second sensor for monitoring the temperature of the heating medium; and
setpoint control means for controlling the setpoint of the heating medium such that the setpoint temperature of the heating medium is lowered as the monitored temperature of the controlled space approaches the desired temperature.
According to a fifth aspect of the present invention there is provided a method of controlling the heating of a controlled space utilising a heating system including a heating medium in communication with the controlled space, the method comprising:
(a) selecting a desired temperature for the controlled space;
(b) measuring the actual temperature of the desired space; and
(c) controlling the setpoint of the heating medium such that the setpoint temperature of the medium is lowered as the measured temperature approaches the desired temperature.
These aspects of the invention are suitable for use in heating systems utilising electrical heating means.
An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 is a block interconnection diagram of a control system according to a first embodiment of the present invention;
Figure 2 is a flowchart illustrating the operation of the system of Figure 1;
Figure 3 is a graph illustrating typical boiler output temperature and controlled space temperature variation with time of a space heating system controlled by the system of
Figure 1;
Figure 4 is a circuit diagram of a main control unit of a control system according to a first embodiment of the present invention;
Figure 5 is a circuit diagram of a remote unit of a control system according to a first embodiment of the present invention;
Figure 6 is a circuit diagram of a solid fuel boiler actuator for use in conjunction with a control system of the present invention; and
Figure 7 shows an electro-mechanical actuator for the control of solid fuel appliances, using the circuitry of
Figure 6.
Reference is first made to Figure 1 of the drawings, which illustrates a block diagram the control system according to a first embodiment of the present invention.
The system is intended for use in conjunction with a wet heating system, in which heated water from a boiler, which may be oil, gas or solid fuel fired, is circulated through a series of radiators located in the space to be heated.
The heated water, or driving fluid, is also passed through a coil in the hot water storage vessel, to provide a supply of domestic hot water (DHW). In this particular example the control unit is also utilised to control operation of an air conditioning unit.
Figure 1 illustrates a main control unit 10, which may positioned in any suitable location though is likely to be located on or adjacent the boiler housing. The main control unit 10 is linked to a remote unit 12 located with a controlled space, and for a domestic application the unit 12 is likely to be sited with the living or sitting room of the home. The unit 12 incorporates a first sensor for monitoring the temperature of the controlled space and a first operator input, typically in the form of a dial, for selecting a desired temperature for the controlled space.
Also linked to the main unit is a DHW thermostat 14 which is provided in conjunction with a second operator input allowing the householder to select a desired setpoint temperature for the domestic hot water. As will be described, the heating system may operate in one of a number of modes, for example for providing hot water heating only, or providing space heating and hot water heating. To control the flow of driving fluid from the boiler between the space heating and domestic water heating circuits, a motorised valve MV1 is provided and operates under control of the unit 10.
The main control unit 10 also receives inputs from a second sensor 16 which monitors the temperature of water output by the boiler, the operation of the boiler being controlled by a burner control 18 under command from the main control unit 10. A conventional timer\programmer 20 allows the householder to control the timing of the operation of the heating system.
The control system is principally intended to be used in conjunction with oil or gas fired heating systems, but may also be utilised to control a solid fuel burner and thus may incorporate a solid fuel burner control 22 linked to the main control unit 10.
The control system operates in one of three modes; mode 1 - central heating only; mode 2 - central heating and domestic hot water; and mode 3 - full central heating and air conditioning. These modes will be described generally below, and will be followed by a detailed description of the circuitry and operation of an embodiment of the present invention.
The operation of the control system is also illustrated by the flowchart shown in Figure 2 of the drawings.
Mode 1 is the default mode of operation and is represented by the right hand path of the flowchart. Once the heating system is switched on by the operator, or by the heating timer, the air temperature in the space to be heated is constantly monitored and compared with the temperature selection made by the operator using the first operator input. The setpoint of the central heating boiler is automatically adjusted by the control system to provide a higher or lower running temperature, depending on the value of the temperature difference measured, that is the greater the measured temperature differential below the operator selected temperature the higher the boiler setpoint temperature and the lower the measured temperature differential the lower the boiler setpoint temperature. A typical temperature profile of space temperature and boiler temperature is illustrated in Figure 3 of the drawings. If the measured temperature is higher than the operator selected temperature the boiler setpoint temperature is further reduced eventually switching off the boiler until the measured differential indicates that the operator setpoint temperature has been achieved.
Mode 2 is the most common mode of operation for domestic installations, and brings the process represented by the left hand path of the flowchart into play. The control system operates as described in mode 1 unless or until the domestic hot water tank thermostat switches on indicating that the temperature of the stored water in the tank has fallen below the temperature selected by the operator. At this point the boiler setpoint control is deactivated allowing the boiler to fire under the control of its own thermostat which is set to facilitate rapid reheating of the domestic hot water, that is boiler setpoint temperature is relatively high. During the domestic hot water reheat period the space temperature is maintained by controlling the position of the motorised water control valve MV1 in the space heating water circuit; if the space temperature falls below the temperature selected by the operator the valve MV1 is opened to allow heated water to circulate through the radiators.
Mode 3 will normally only be required by commercial operators in the U.K. However in countries with warmer climates this may be the most common mode of operation. The control system operates as above with the additional feature of switching on air conditioning plant in the event of the measured space temperature being higher than the operator selected space temperature.
As mentioned above, the solid fuel burner control is an optional unit, and is provided in conjunction with an electro-mechanical actuator. The actuator unit is designed to enable the boiler temperature setpoint voltage output from the main unit to control the position of an air inlet damper as found on many enclosed solid fuel heating appliances. By controlling the position of the air inlet damper the quantity of air entering the combustion area of the appliance can be controlled. The rate of fuel combustion and hence the boiler running temperature is then controlled via the above system.
Reference is now made to Figure 4 of the drawings, which illustrates a circuit diagram of an exemplary main unit 10 comprising: D.C. power supply (transformer L1, bridge rectifier G1, capacitor C1 and voltage regulator
U3), first instrumentation amplifier (operational amplifiers U1A, UlB and U1C, resistors Rl, R2, R3, R4,
R5,), space heating control amplifier (differential amplifier U2C, times two amplifier U4D, resistors R16, R17,
R31, R32 and R22, capacitor C4), multiplier amplifier (operational amplifier U2D, resistors R12 and R13), second instrumentation amplifier (operational amplifiers U2A, U2B, and UlD, resistors R7, R8, R9, Rl0 and R11), low temperature clamp (differential amplifier U4B, times two amplifier U4C, resistors R27, R28, R15, R29, R30, and R26, transistors T3, T5 and capacitor C3) buffer amp (operational amplifier U4A, resistors R14 and R21, capacitor C2, and diode D2), matching network (resistors
R19, R6, R18 and R20), relay 1 driver (transistor T2, diode D1), relay 2 driver (transistor T1, diode D4), relay 3 driver (transistor T4, diode D7, resistor R25 and capacitor C5), optical isolator (optical isolator U1, diode D6, resistors R23 and R24), double pole, double throw relays (rel 1, rel 2 and rel 3), 240 volt mains supply terminals (terminal block J1), remote unit terminals (terminal block
J2), 12 volt thermostat terminals (terminal block J3), 240 volt thermostat terminals(terminal block J5), burner control terminals (terminal block J6) and space heating valve control terminals (terminal block J7).
Figure 5 of the drawings illustrates the circuit diagram of an exemplary remote unit 12 comprising: temperature sensor (semiconductor temperature sensor U3), buffer amplifier (operational amplifier UlD), times ten amplifier (operational amplifier UlC, resistors R2, R3 and
R4), clamping circuit (operational amplifier UlA, transistors T1 and T2, resistors R1, R5 and R6, switch SW1), temperature selector (operational amplifier U1B, variable resistor P1, resistors R6 and R7), output\power supply terminals (terminal block Jl) and second sensor terminals (terminal block J4).
Figure 6 of the drawings illustrates the circuit diagram of an exemplary solid fuel boiler actuator unit comprising: power supply (fuse F1, transformer Ll, bridge rectifier Gl, reservoir capacitor Cl and voltage regulator
U2), input buffer amplifier (operational amplifier U1A), variable gain amplifier (operational amplifier U1B and resistors R1, R2, R3), solenoid driver(transistors T1, T2 and diode D1) and solenoid L2.
The operation of the main unit 10, will now be described, with particular reference to Figure 4. At switch on power is supplied to the 240 volt mains supply terminals and hence the primary winding of the step down transformer L1 which provides a 12 volt AC output to the bridge rectifier G1. The bridge rectifier and reservoir capacitor C1 supply approximately 17 volts DC to voltage regulator U3 which in turn provides a 12 volt regulated power supply
A voltage relative to 100 mV per degrees centigrade (air temperature in the controlled space) is monitored via the remote unit terminal 1 and a voltage relative to the position of the first operator input dial is monitored via the remote unit terminal 2. A voltage relative to the temperature of the driving fluid in the boiler is monitored via the second sensor terminals. The setpoint status of the domestic hot water tank thermostat is monitored via the 12 volt or the 240 volt thermostat terminals. The voltages at the remote unit terminals 1 and 2 are compared by the first instrumentation amplifier, the output of which is supplied to the non inverting input of the second instrumentation amplifier via the multiplier amplifier.
This voltage is then used as the boiler setpoint reference.
The second instrumentation amplifier then compares the boiler setpoint reference voltage with a voltage supplied to its inverting input by the second sensor via the second sensor terminals and matching network. A voltage proportional to the voltage differential between the non inverting and the inverting inputs to the second instrumentation amplifier is supplied from the output of the second instrumentation amplifier to switch relay 1 via the relay 1 driver. When the voltage supplied to the relay 1 driver is above the conduction threshold of transistor T2 (approx .6 volts) relay 1 will be energised and the power supply to the burner via the burner control terminal 2 will be interrupted switching off the burner. If the setpoint status of the domestic hot water storage tank thermostat changes (detecting that the temperature of the domestic hot water in the storage tank has fallen below the second operator setpoint) a 12 volt signal will be supplied to terminal 2 on the 12 volt thermostat terminals. This 12 volt signal then supplies the coil of relay 3 enabling relay 3 to operate via the relay 3 driver. A 240 volt signal will be supplied to terminal 2 on the 240 volt thermostat terminals. This signal is supplied to the input side of the optical isolator which switches a 12 volt supply to the base terminal of the relay 3 driver transistor T4 forcing the transistor into saturation and energising relay 3. When relay 3 is energised the power supply to relay 1 is interrupted by the opening of the contacts REL3C. This inhibits the operation of relay 1 therefore maintaining relay 1 in the de-energised position and allowing the burner to operate under the control of its own thermostat only. When relay 3 is energised and therefore contacts REL3B open, the motorised valve MV1 is then controlled by relay contacts REL2C. During the domestic hot water reheating period the operation of relay 2 and hence the contacts REL2C are controlled as follows:
The voltage supplied from the output of the multiplier U2D is supplied to the inverting input of U2C which functions as a differential amplifier; a reference voltage is supplied to the non-inverting input of U2C; the output from the differential amplifier U2C is then supplied to the noninverting input of amplifier U4D which supplies a damped and amplified signal base terminal of the relay 2 driver transistor T1. If the voltage supplied to the relay 2 driver is above the conduction threshold of transistor T1 (approximately 600 m.V.) relay 2 is energised causing contacts REL2C to open and interrupt the power supply to motorised valve MV1 causing MV1 to close and interrupt the flow of driving fluid to the space heating circuit.
The function of the low temperature clamp is to inhibit operation of the burner below a temperature limit set by the installer and operates as described below. The boiler setpoint reference voltage supplied from the output of the multiplier U2D is supplied to the non-inverting input on operational amplifier U4B which operates as a differential amplifier, the output of which is supplied to the base of transistor T3. Variable resistor R15 supplies an adjustable reference voltage to the inverting input of
U4B. The output from U4B is then supplied to amplifier U4C which supplies a damped and amplified signal to the base terminal of transistor T3. Resistor R15 is adjusted on installation against a calibrated scale so as to hold transistor T3 in saturation only above a minimum operating temperature limit in accordance with the manufacturers specifications for the boiler. A 12 volt supply is supplied to the base terminal of transistor T5 via resistor
R26. When transistor T3 is held in saturation the voltage supplied to the base terminal of transistor T5 via resistor
R26 is shunted to the zero volt line of the power supply so as to hold transistor T5 out of saturation. If the setpoint reference voltage supplied from the output of the multiplier U2D is below the setpoint voltage required to operate the boiler above the minimum temperature selected by the installer the voltage supplied to the base of transistor T3 will fall causing transistor T3 to come out of saturation and allow the voltage at the base terminal of transistor T5 to rise above the conduction threshold of transistor T5 (approx .6volts). Transistor T5 then conducts and energises relay 1 opening contacts REL1B inhibiting operation of the burner.
The operation of the remote unit 12 will now be described, with specific reference to Figure 5. At switch on of the main unit 10 a 12 volt supply is supplied to terminal 1 of terminal block J1. The first sensor U3 supplies an output voltage of 10 mV per degrees centigrade (air temperature in the controlled space) relative to zero degrees centigrade to the input of the buffer amplifier
U1D. The output voltage from the buffer amplifier U1D is then multiplied by the times ten amplifier U1C. The output voltage from the times ten amplifier U1C is then 100 mV per degrees centigrade relative to zero degrees centigrade.
The output from the times ten amplifier U1C is then supplied to terminal 3 on terminal block J1 via resistor
R2. This supplies the main unit with a space temperature reference voltage. The first operator input P1 supplies an operator setpoint reference voltage to terminal 4 of terminal block J1 via buffer amplifier U1B.
The purpose of the clamping circuit is to artificially hold the space temperature reference voltage low until the measured space temperature is within 5 degrees centigrade of the temperature selected at the first operator input at which point the clamping circuit progressively allows the space temperature reference voltage to return to the actual measured space temperature voltage. This function can be inhibited by the operator via selector switch SW1.
The clamping circuit operates as described below.
When the measured space temperature is 5 degrees centigrade or more below the temperature selected at the first operator setpoint the space temperature reference voltage supplied to terminal 3 of the terminal block J1 is shunted to the zero volt power supply rail by transistor Tl.
Resistors R5 and R6 supply a voltage proportional to the output voltage supplied to the input of the buffer amplifier UlB to the non-inverting input of the comparator
U1A. This voltage is compared with the input voltage supplied to the inverting input of the comparator from the output of the buffer amplifier U1A. The output voltage from the comparator is supplied to the base terminal of transistor T2. The output voltage from the comparator U1A remains low and holds the transistor T2 out of conduction until the voltage supplied to its inverting input approaches the voltage supplied to its non inverting input at which point the voltage at the output of the comparator
U1A tends to rise above the conduction threshold of transistor T2 (approximately 600 mV). Transistor T2 then begins to conduct and progressively shunts the voltage at the base of transistor T1 to the zero volt line of the power supply. As the voltage supplied to the base terminal of transistor T1 progressively reduces the conduction of transistor T1 also progressively reduces allowing the space temperature reference voltage to progressively return to its correct measured value.
The operation of the electro-mechanical solid fuel boiler actuator will now be described, with specific reference to Figures 6 and 7 of the drawings. A 240 volt
A.C. power supply is supplied to the primary windings on stepdown transformer L1 via fuse F1. Stepdown transformer
L1 provides a 12 volt A.C. supply to bridge rectifier G1.
Bridge rectifier G1 and reservoir capacitor C1 then provide an output voltage of approximately 17 volts D.C.
unregulated which is supplied to the voltage regulator U2.
The voltage regulator U2 provides a 12 volt D.C. regulated power supply.
At switch on of the main unit 10 the voltage output from the main unit buffer amp U4A is supplied to the actuator unit input buffer U1A via the actuator sense terminal (terminal 1 on connector block J2). The output voltage from the input buffer U4A is then supplied to the non-inverting input terminal of the variable gain amplifier
U1B where this voltage is then amplified by a factor dependent on the position of the variable resistor R3. The output voltage from the variable gain amplifier is then supplied to the base terminal of transistor T1. Transistor T1 and T2 form a high current driver for solenoid L2. As the voltage supplied to the base terminal of transistor T1 tends to rise the driving current supplied to the base of transistor T2 tends to increase. As the driving current supplied to the base terminal of transistor T1 increases the not intended to limit the scope of the invention in any way. Further, embodiments of the present invention have applications in control of equipment other than space heating and air conditioning, such as the control of industrial chillers and cold stores, and industrial ovens including those heated by electrical means. Embodiments of the invention may also be utilised for control of electrically heated radiators and central bulk storage heating appliances. On a larger scale, multi-channel industrial control systems may be provided for use in full building energy management control. Such industrial units operate under the same principles as the embodiment described above, with enhanced features which enable the units to control larger buildings with multiple boiler plant and zones, may employ microprocessor technology and includes a user friendly programming system enabling unskilled operators to program the operation of heating, ventilation and air conditioning systems within a large building without the need for a complex instruction manual. All data transmission to and from the industrial unit can be made using any combination of three separate transmission systems: low voltage hard wire; mains supply cable carrier transmission (this system of transmission uses the mains power cables already present in the building to transmit data by modulating a high frequency carrier signal with the data to be transmitted) which dramatically reduces installation costs in terms of new cable requirements and installation time; and radio signal transmission (for use in smaller buildings utilising 418
MHz transmitters and receivers approved to DTI MPT1340).
Embodiments of the present invention allow use of low voltage control signals in key safety areas such as the operator inputs and sensors which not only enhances the safety of the system but also enables the installer to make use of considerably cheaper cable in areas where the long cables involved contribute significantly to the cost of the installation. Low voltage multi-core telecom cable has been used successfully and has the added advantage of allowing unprotected surface mounting in areas where access to wall cavities is limited.
Claims (17)
1. A control system for a heating or air conditioning system for a controlled space, the heating or air conditioning system supplying a heaved or cooled fluid from a fluid source to the controlled space, the control system comprising:
a first sensor for monitoring the temperature of the controlled space;
first operator input means for operator selection of a desired temperature for the controlled space;
a second sensor for monitoring the temperature of the heated or cooled fluid output by the fluid source; and
setpoint control means for controlling the setpoint of the fluid source such that the setpoint temperature of the heated or cooled fluid is lowered or raised as the monitored temperature of the controlled space approaches the desired temperature.
2. The system of claim 1, in combination with a wet heating system.
3. The system of claim 1 or 2, for use with a heating system, further comprising a third sensor for monitoring the temperature of water contained in a storage vessel for use as domestic hot water (DEW), second operator input means for operator selection of a desired setpoint temperature for the water, and means for controlling circulation of heated fluid from the fluid source through the storage vessel, said controlling means permitting said circulation of heated fluid when the measured temperature falls below the desired temperature.
4. The system of claim 3, wherein said controlling means includes a motorised valve, and the valve is configured to direct a proportion of the heated fluid supply to the controlled space if the measured temperature in the controlled space is below the desired temperature.
5. The system of claim 3 or 4, wherein, when heated fluid is being circulated through the storage vessel the setpoint control means is overridden, such that the fluid source setpoint remains relatively high to permit rapid heating of the water in the vessel.
6. The system of any of the preceding claims, wherein the setpoint control means maintains the setpoint at a maximum or minimum temperature until the measured temperature comes within a predetermined range of the desired temperature, and then lowers or raises the setpoint temperature as the measured temperature approaches the desired temperature.
7. The system of claim 6, wherein the setpoint control means maintains the setpoint at a maximum or - inimum temperature until the measured temperature comes within 50C of the desired temperature.
8. The system of any of claims 3 to 7, wherein the system permits separate timed control of space heating or cooling and domestic hot water heating via external timers or programmers.
9. The system of any of the preceding claims, for use with solid fuel appliances, including a dedicated electromechanical actuator for adjusting an air inlet damper.
10. The system of any of the preceding claims, wherein the first sensor and first operator input means are provided in a single remote unit for location in the controlled space.
11. The system of any of the preceding claims, wherein the second sensor and setpoint control means are provided in a single main unit for location on the fluid source.
12. The system of any of the preceding claims, wherein one or more of the sensors are in the form of a semiconductor transducers.
13. A heating or air conditioning system including a control system according to any of claims 1 to 12.
14. A method of controlling the heating or air conditioning of a controlled space utilising a heating or air conditioning system supplying a heated or cooled fluid from a fluid source to the controlled space, the method comprising:
(a) selecting a desired temperature for the controlled space;
(b) measuring the actual temperature of the desired space; and
(c) controlling the setpoint of the fluid source such that the setpoint temperature of the heated or cooled fluid is lowered or raised as the measured temperature approaches the desired temperature.
15. A control system for a heating system for a controlled space, the heating system including a heating medium for location in the controlled space, the control system comprising:
a first sensor for monitoring the temperature of the controlled space;
first operator input means for operator selection of a desired temperature for the controlled space;
a second sensor for monitoring the temperature of the heating medium; and
setpoint control means for controlling the setpoint of the heating medium such that the setpoint temperature of the heating medium is lowered as the monitored temperature of the controlled space approaches the desired temperature.
16. A method of controlling the heating of a controlled space utilising a heating system including a heating medium in communication with the controlled space, the method comprising:
(a) selecting a desired temperature for the controlled space;
(b) measuring the actual temperature of the desired space; and
(c) controlling the setpoint of the heating medium such that the setpoint temperature of the medium is lowered as the measured temperature approaches the desired temperature.
17. A control system for a heating system for a controlled space substantially as described herein and as illustrated in Figures 1 to 5, or Figures 6 and 7, of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9617287A GB2320966A (en) | 1996-08-16 | 1996-08-16 | Control system for heating or air conditioning |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9617287A GB2320966A (en) | 1996-08-16 | 1996-08-16 | Control system for heating or air conditioning |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9617287D0 GB9617287D0 (en) | 1996-09-25 |
| GB2320966A true GB2320966A (en) | 1998-07-08 |
Family
ID=10798610
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9617287A Withdrawn GB2320966A (en) | 1996-08-16 | 1996-08-16 | Control system for heating or air conditioning |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2320966A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2167162A1 (en) * | 1998-11-27 | 2002-05-01 | Sansung Electronics Co Ltd | Power saving operational control method of air conditioner |
| EP1235130A3 (en) * | 2001-02-23 | 2005-01-26 | Techem Service Aktiengesellschaft & Co. KG | Method and device for controlling the room temperature |
| EP2363659A1 (en) * | 2010-01-08 | 2011-09-07 | Daikin Industries, Ltd. | Radiator |
| GB2528946A (en) * | 2014-08-07 | 2016-02-10 | Husky Heat Pumps Ltd | Improved heating system |
| FR3101447A1 (en) * | 2019-10-01 | 2021-04-02 | Valeo Systemes Thermiques | Thermal management method, in particular for a motor vehicle, and associated thermal management strategy and control unit |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1468393A (en) * | 1973-04-04 | 1977-03-23 | Maxitrol Co | Temperature control system for a space |
| EP0173770A1 (en) * | 1984-09-05 | 1986-03-12 | Furigas Electronics N.V. | Room thermostat for a gas-fired central heating system |
| GB2215494A (en) * | 1988-02-01 | 1989-09-20 | Mitsubishi Electric Corp | Control device for an air conditioner with floor temperature sensor |
| EP0343128A2 (en) * | 1988-05-17 | 1989-11-23 | FERROLI INDUSTRIE RISCALDAMENTO S.p.A. | Heating system including an assembly for automatically adjusting the temperature of the heating water |
| GB2231692A (en) * | 1989-04-28 | 1990-11-21 | Toshiba Kk | Heat pump heating apparatus |
-
1996
- 1996-08-16 GB GB9617287A patent/GB2320966A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1468393A (en) * | 1973-04-04 | 1977-03-23 | Maxitrol Co | Temperature control system for a space |
| EP0173770A1 (en) * | 1984-09-05 | 1986-03-12 | Furigas Electronics N.V. | Room thermostat for a gas-fired central heating system |
| GB2215494A (en) * | 1988-02-01 | 1989-09-20 | Mitsubishi Electric Corp | Control device for an air conditioner with floor temperature sensor |
| EP0343128A2 (en) * | 1988-05-17 | 1989-11-23 | FERROLI INDUSTRIE RISCALDAMENTO S.p.A. | Heating system including an assembly for automatically adjusting the temperature of the heating water |
| GB2231692A (en) * | 1989-04-28 | 1990-11-21 | Toshiba Kk | Heat pump heating apparatus |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2167162A1 (en) * | 1998-11-27 | 2002-05-01 | Sansung Electronics Co Ltd | Power saving operational control method of air conditioner |
| EP1235130A3 (en) * | 2001-02-23 | 2005-01-26 | Techem Service Aktiengesellschaft & Co. KG | Method and device for controlling the room temperature |
| EP2363659A1 (en) * | 2010-01-08 | 2011-09-07 | Daikin Industries, Ltd. | Radiator |
| EP2363659A4 (en) * | 2010-01-08 | 2012-10-31 | Daikin Ind Ltd | Radiator |
| GB2528946A (en) * | 2014-08-07 | 2016-02-10 | Husky Heat Pumps Ltd | Improved heating system |
| FR3101447A1 (en) * | 2019-10-01 | 2021-04-02 | Valeo Systemes Thermiques | Thermal management method, in particular for a motor vehicle, and associated thermal management strategy and control unit |
| WO2021064309A1 (en) * | 2019-10-01 | 2021-04-08 | Valeo Systemes Thermiques | Method for heat management, in particular for a motor vehicle, and associated heat management strategy and control unit |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9617287D0 (en) | 1996-09-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |