IES20100663A2

IES20100663A2 - A fuel consumption controller

Info

Publication number: IES20100663A2
Application number: IE20100663A
Authority: IE
Inventors: Gerard James Shaw; Trevor Gordon
Original assignee: Ecoce Engineering Ltd
Priority date: 2009-10-14
Filing date: 2010-10-14
Publication date: 2011-04-27
Also published as: GB2474454A; IE20100662A1; WO2011045776A1; GB0917975D0

Abstract

This invention relates to a fuel consumption controller for a heating installation burner, a method of controlling a heating installation burner and a heating installation comprising a burner. The fuel consumption controller can set a fuel consumption volume limit for a time period, monitor when the burner is firing, estimate the amount of fuel that has been burnt using the time that the burner has been firing and a flow rate specification of a fuel nozzle through which the fuel is delivered into the burner, compare the estimated amount of fuel that has been burnt with the fuel consumption limit and limit the operation of the burner for the remainder of the time period on the amount of fuel estimated to have been burnt reaching the fuel consumption limit. By providing such a fuel consumption controller and method, the owner of the household or premises can carefully control fuel consumption and provide a more predictable operating cost of the burner. <Figure 1>

Description

Introduction This invention relates to a fuel consumption controller for a heating installation burner, a method of controlling the heating installation burner and a heating installation having the fuel consumption controller.

A significant proportion of buildings equipped with a heating installation have either an oil-fired or a gas-fired burner. The burner is used to heat water or other fluid which in turn is circulated throughout the building to heat the building. There is a significant problem with the known heating installations in that the cost of operating the oil-fired or gas-fired burner is highly unpredictable.

There are several reasons why the cost of operating the burner is unpredictable. First of all, the operation of the burner is largely dependent on weather and climatic conditions which are beyond the control of the operator of the burner. Secondly, the building inhabitants preferences relating to the optimum temperature of the building can significantly alter the cost of operating the burner and in buildings where there are several different inhabitants, this can lead to greater unpredictability of burner running cost. Thirdly, the heating installation burners are often left on as a result of human error for sustained periods of time when the burner is not required. The burner can be operating for a significant length of time before the error is rectified and even then it is usually difficult to determine how long the burner has been left on in error, Finally, the condition of the burner equipment can have a significant bearing on the efficiency of the burner which in turn has a bearing on the amount of oil or gas used by the heating installation burner to heat the house or premises. In combination, the above circumstances result in highly unpredictable running costs of the heating installation burner.

Another problem with the known heating installations that operate using oil-fired burners is that due to the unpredictable rate of fuel consumption of the burner, it is quite common for the heating installation to run out of fuel. Various surveys have shown that fc 1 o 06S 3 -2to heat their household at some stage. Various devices have been developed to monitor the amount of fuel remaining in an oil tank and to alert the building occupant when the amount of fuel fails below a predetermined limit, thereby reminding the occupant to order more fuel. However, these devices only alert the occupant that the fuel is running low and they do not allow the home owner to control or preset the rate of consumption of the fuel.

It is an object of the present invention to provide a fuel consumption controller for a heating installation burner and a method of controlling a heating installation burner that enable the operator of the heating installation to carefully control the fuel consumption by the burner resulting in a more predictable operating cost of the burner.

Statements of Invention According to the invention there is provided a method of controlling a heating installation burner comprising the steps of: setting a fuel consumption limit for the burner for a control time period; monitoring the operation of the burner during the control time period; estimating the fuel consumption of the burner in the control time period using the amount of time that the burner has been firing in the control time period and a flow rate specification of a fuel nozzle through which fuel is supplied to the burner; comparing the estimated fuel consumption for the control time period with the fuel consumption limit for the control time period; and on the estimated fuel consumption for the contra! time period reaching the fuel consumption limit for the control time period, limiting operation of the burner for the remainder of the control time period. i£ 1 Ο Ο 66 3 -3By having such a method, it is possible to control the amount of fuel that is burnt in any given time period, for example, an hour time period. In this way, the operating cost of the burner will be far more predictable. The operator of the burner can select precisely how much fuel they wish to burn in that hour time period by setting the fuel consumption limit and the method will prevent more than the desired amount of fuel being burnt. This is possible in part due to the very simple manner in which the amount of fuel being burnt in the time period is calculated, namely by using the flow rate specification of the nozzle through which the fuel is supplied to the burner in conjunction with the time that the burner is operational. By using the flow rate specification along with the time in which the burner is operational, the amount of fuel being burnt can be determined simply without the need for expensive sensors or sensors positioned in hostile environments such as within a fuel tank. Furthermore, the above method can operate equally well with gas-fired burners.

In one embodiment of the invention the method comprises the initial step of setting the flow rate specification of the nozzle. By allowing the user to set the initial flow rate specification of the nozzle, the method can be used with a variety of different nozzle sizes and burners. The operator simply selects the appropriate nozzle size in their burner and the method will then calculate the fuel consumption according to that nozzle size.

In one embodiment of the invention the step of setting the fuel consumption limit for the control time period further comprises the steps of: setting a second fuel consumption limit for a second control time period, greater than the fuel consumption limit and the control time period respectively; and thereafter calculating the fuel consumption limit for the control time period. This is seen as a particularly useful aspect of the present invention as the operator may determine the amount of fuel that they wish to use over a time period that is more meaningful to them. For example, the operator may decide that they wish to use 250 liters of fuel, approximately a quarter of a standard tank, over a thirty, sixty or ninety day time period and the amount of fuel that can be used for each hour of that time period is then calculated. In many cases, an hour is used as the control time period due to the fact that by having a relatively short control time period, the heating installation will not be allowed to cool down too much as a result of the burner being inoperable for large periods of time.

IE 1 Ο Ο 6 6 3 -4Ιη one embodiment the method comprises the step of apportioning some of the second fuel supply limit to a fuel bank.

In one embodiment of the invention some of the second fuel supply limit is apportioned to the fuel bank prior to the calculation of the fuel consumption limit for the control time period.

In one embodiment of the invention between 5% and 20% of the second fuel supply limit is apportioned to the fuel bank. In one embodiment, between 10% and 15% of the second fuel supply limit is apportioned to the fuel bank. Preferably, 12.5% of the second fuel supply limit is apportioned to the fuel bank.

In one embodiment of the invention there is provided a method in which the fuel consumption limit for the control time period is increased by a predetermined portion of the fuel bank. This is seen as a particularly important aspect of the present invention, By having a fuel bank, the method will be far more flexible in that it will allow more fuel to be used initially to heat up the building from cold. Furthermore, the fuel bank will allow the fuel to be used if and when it is needed, for example early in the morning or during the evening/night rather than a less flexible method in which the amount of fuel that may be burnt is exactly the same in each control time period, In one embodiment of the invention there is provided a method in which the predetermined portion of the fuel bank that may be burnt in any one control time period is limited to a predetermined percentage of the fuel bank calculated at the beginning of the control time period. It is envisaged that between 10% and 30% of the fuel bank may be burnt in any one control time period. Ideally, 20% of the fuel bank may be burnt in any one control time period.

In one embodiment of the invention the predetermined portion of the fuel bank that may be burnt in any one control time period is limited to a multiple of the fuel consumption limit. It has been found that a multiple of between 2 and 8 times the fuel consumption limit, more preferably between 3.5 and 6.5 times the fuel consumption limit and ideally 5 -5IE 1 Ο 0 66 3 times the fuei consumption limit will provide sufficient additional fuel to satisfy irregular fuel burn requests over the course of a day.

In one embodiment of the invention the step of comparing the estimated fuel consumption for the control time period with the fuel consumption limit for the control time period comprises the steps of: at the start of a control time period, setting a pulse counter with an integral number of pulses representative of the fuel consumption limit; generating a pulse each time a predetermined amount of fuel has been burnt; and decrementing the pulse counter by one each time a pulse is generated until the pulse counter reaches zero.

This is seen as a particularly simple way of comparing the estimated fuel consumption for the control time period with the fuei consumption limit for the control time period. The amount of time necessary for a specified amount of fuel to pass through a given nozzle can be determined from the nozzle flow rate specification. Therefore, for a given time period that the nozzle is in operation, it is known how much fuel has passed through the nozzle. When the burner has been on for the given time period, a pulse is generated, indicative that the burner has burnt the predetermined amount of fuel. Similarly, it is possible to calculate the amount of time required to reach the fuel consumption limit and by extension the number of pulses that would need to be generated in order to reach that fuel consumption limit A pulse counter is set at the appropriate number of pulses representative of the fuel consumption limit and each time the burner is in operation for the given time period, a pulse is generated and the pulse counter is decremented by one. When the pulse counter reaches zero, the maximum amount of fuel allowed has been used.

In another embodiment of the invention there is provided a controller for a heating installation burner comprising: means to set a fuel consumption volume limit for the burner for a control time period; means to monitor when the burner is firing during the control time period; te 1 0 0663 -6means to estimate the amount of fuel that has been burnt by the burner in the control time period using the amount of time that the burner has been firing in the control time period and a flow rate specification of a fuel nozzle through which fuel is delivered into the burner; means to compare the estimated amount of fuel that has been burnt in the control time period with the fuel consumption limit for the control time period; and means to limit the operation of the burner for the remainder of the control time period on the amount of fuel estimated to have been burnt in the control time period reaching the fuel consumption limit for the control time period.

In one embodiment of the invention there is provided means to receive the flow rate specification of the nozzle.

In one embodiment of the invention there is provided a controller having a flow rate table with a flow rate for the control time period for the flow rate specification.

In one embodiment of the invention the means to set the fuel consumption limit for the control time period further comprises: means to receive a second fuel consumption limit for a second control time period, greater than the fuel consumption limit and the control time period respectively; and means to calculate the fuel consumption limit for the control time period.

In one embodiment of the invention the controller comprises means to apportion some of the second fuel supply limit to a fuel bank prior to calculating the fuel consumption limit for the control time period.

In one embodiment of the invention the controller has means to increase the fuel consumption limit for the control time period by a predetermined portion of the fuel bank.

In one embodiment of the invention there is provided a controller in which the means to compare the estimated amount of fuel that has been burnt in the control time period with the fuel consumption limit for the time period comprises a pulse counter; and in which IE 1 0 0 66 3 -7there is provided: means to set the pulse counter with an integral number of pulses representative of the fuel consumption limit; means to generate a pulse each time a fixed volume of fuel has been burnt; and means to decrement the pulse counter on a pulse being generated.

In a further embodiment of the invention there is provided a household heating installation comprising the controller.

Detailed Description of the Invention The invention will now be more clearly understood from the following description of some embodiments thereof given by way of example only with reference to the accompanying drawings, in which:15 Figure 1 is a diagrammatic representation of a heating installation according to the present invention; Figure 2 is a diagrammatic representation of a fuel consumption controller in accordance with the invention; Figure 3 is a table showing the oil/fuel rate in US Gallons per hour for different nozzle sizes; and Figures 4(a) and 4(b) are pulse trains for two different nozzle sizes and two different fuel consumption rates.

Referring to Figure 1, there is shown a heating installation, indicated generally by the reference numeral 1, comprising a heating installation burner 3, a controller 5, a fuel tank 7 and a fuel feed line 9 that delivers fuel from the fuel tank 7 to the burner 3. The heating installation further comprises a boiler 11 containing a fluid, in this case water, and a pump 13 to circulate the water from the boiler 11 around the building’s heating system (not shown) through flow and return pipes 15,17. In addition to the above, there is provided a control thermostat 19, a safety thermostat 21 and a fuse 23 through which the control signal to operate the heating installation burner 3 are passed. The controller 5, control thermostat IE 1 0066 3 -819, safety thermostat 21 and fuse 23 are mounted on a live line 25 and there are further provided a neutral line 27 and an earth line 29, The heating installation burner 3 has a nozzle 31 which is a calibrated device that delivers a fixed quantity of fuel therethrough over a given time period. The amount of fuel that is delivered through the nozzle 31 is dependent on the size and design of the nozzle.

In use, the control thermostat 19 provides a signal based on the actual temperature in the building and the desired temperature in the building as to whether or not the burner should operate. This signal is passed to the controller 5 which checks the amount of fuel that may be burned in a given time period and determines the amount of fuel that has already been burnt in the time period and whether or not the burner is to be allowed to burn. If the burner 3 is allowed to burn, the controller 5 passes on the control signal from the thermostat to the burner 3. If the burner is not allowed to burn, the controller 5 inhibits the control signal from the thermostat to the burner 3 if necessary. Effectively therefore, the controller regulates the control signal from the control thermostat 19. If the burner is instructed to fire, fuel is delivered from the fuel tank 7 through the fuel feed line 9 and out through the nozzle 31 where it is combusted in a burner flame 33. The combusted fuel is used to heat the water in the boiler 11. The heated water in the boiler 11 is then circulated through the heating system to heat the house or premises.

Referring to Figure 2, there is shown a diagrammatic representation of a fuel consumption controller 5 for a heating installation burner. The fuel consumption controller 5 comprises a casing 41 having a liquid crystal display (LCD) screen 43, a female socket connection 45, a male socket connection (not shown) and various control switches 47, 49, 51, 53. Control switch 47 is a fuel consumption limit set switch which may be operated to allow a user to determine the amount of fuel that is to be burnt by the burner in a given time period, usually an hour time period. The control switch 49 is a nozzle flow rate specification switch which allows the flow rate of a particular nozzle to be input into the controlier. Control switch 51 comprises an override switch and control switch 53 comprises a calibrate switch. The fuel consumption controller further comprises a plurality of LEDs 55, 57, 59 to shown status of the controller. It will be understood that the LCD screen 43 is optional in some cases and the LEDs 55,57 and 59 may provide sufficient status information.

IE 1 Ο Ο 6 6 3 -9Ιη use, an operator of the heating installation sets the nozzle flow rate specification switch 49 to correspond to the flow rate specification of the nozzle 31 in the burner 3. The operator then sets the amount of fuel that they wish to burn by adjusting the fuel consumption limit switch 47. The user presses the calibrate switch 53 and the unit calculates the fuel consumption limit and begins to monitor the amount of fuel consumed by the burner while comparing it to the fuel consumption limit. A clock (not shown) is provided that counts out a desired time period, for example an hour, in which the amount of fuel being consumed is monitored. The controller 5 estimates the fuel consumption based on the time that the burner 3 is operating and the flow rate specification of the fuel nozzle 31.

An algorithm extrapolates the volume of fuel consumed and when the volume of fuel consumed reaches the desired limit the unit will inhibit the burner until the next time period begins. Once the time period has elapsed, the unit will allow the burner to operate again provided that the burner is called to operate. It is envisaged that it is preferable to set the time period as an hourly time period as in this way, the heating system will not have sufficient time to cool down thereby conserving fuel required to bring the system back up to temperature. The override switch 51 allows the user to override the unit and run the burner 3 in the normal mode without any restriction on fuel consumption which may be desired in certain circumstances. If the override switch 51 has been used, the controller 5 will have to be recalibrated before fuel consumption regulation can begin again.

It can be seen from the above that the user can set the duration of time that they wish the fuel to last. For example, they may say that they wish 1000 litres of fuel to last 1000 operating hours of the burner, in which case they can limit tiie amount of fuel to one litre per hour. The controller will thereafter prevent more than one litre of fuel being consumed in any hour of operation ofthe heating installation burner.

In the embodiment shown in Figure 2, the switches 47 and 49 are multi-position rotating knobs however it will be understood that other switches instead of multi-position rotating knobs could be used. The multi-position rotating knobs offer a relatively inexpensive option. As an alternative to the multi-position rotating knob, dipswitches, a larger set of switches each with an individual setting, digital keypad or a touch screen interface could be used. Indeed, other types of switches could be used if desired. tt 1 0 0663 -10Referring to Figure 3, there is shown an oil fuel rate in litres per hour for various different nozzle sizes, indicated generally by the reference numeral 61. For example, it can be shown that for a nozzle size of 0.40 US gal/Hr (the nozzle size is rated in US gal/Hr, United States gallons per hour), using the standard pressure for a heating system (100 psi pressure (6.895 bar)), the fuel bum rate would be 1.51 litres per hour. Therefore, if the user stipulates that only 0.5 litres is to be burned in any given hour, it wiil be understood that the heating installation burner will be operated for no more than 19 minutes 52 seconds every hour ((0.5+ 1.51) = 0.3311*Hour).

Referring to Figures 4(a) and 4(b), there is shown a pair of pulse trains 71, 73 respectively, for different nozzle sizes. Each pulse represents a volume of 10cc of fuel that has been consumed by the burner. Every time there is a pulse, a pulse count-down oounter in the controller 5 is decremented by one. When the pulse count-down counter reaches zero, this indicates that the maximum amount of fuel that may be burned in that time period has been burnt and the operation of the burner will be inhibited for the remainder of that time period.

For example, the fuel bum rate may be set to 1 litre per hour and in the above example this will equate to 100 pulses (100 x 10cc = 1 litre). Therefore, the pulse count-down counter will be set to 100. The controller 5 will monitor the operation of the burner 3 and each time the burner 3 has been on sufficiently long enough to burn 10cc of fuel, the controller 5 will generate a pulse. Each time there is a pulse, the pulse count-down oounter is decremented by one and after 100 pulses the counter will reach 0. Once it reaches 0, the burner will be inhibited from running for the remainder of the chosen time period, for example for the remainder of that hour. Once the remainder of the hour has elapsed, the clock will be reset and the pulse count-down counter will be reset so that fuel can again be delivered to the burner for the next time period until the amount of fuel allotted for that time period has been consumed.

In Figure 4(a), in order to generate the pulse train 71, the nozzle size is set at 0.40 US gal/Hr using control switch 49. After the burner has been burning for a duration of 23.84 seconds, a pulse is generated to indicate that 10cc of fuel has been burnt. If the fuel limit switch is set to allow 100cc of fuel to be burnt, the pulse count-down counter will be set to 10 and there will be 10 pulses allowed per hour to reach the 100cc limit. Once the ten IE 1 0 0663 -11 pulses have been registered, no further pulses will be allowed (in other words, no more fuel will be consumed) until the next time period begins, Therefore, if the burner is operated continuously, there will be 100 pulses after 2384 seconds, just under forty minutes, and if the burner has been operated continuously, the burner will have burnt 1 litre of fuel in that time and the burner will be inhibited for the remainder of the time period, for example the remainder of the hour. It will be understood that the burner may not operate continuously due to the fact that the user, a thermostat device or other device may cut off the burner during the time period when it is not required and therefore the controller only monitors the length of time that the burner is in operation. In the present example, for each 23.84 seconds that the burner is in operation, a pulse is generated and the pulse counter is decremented by one.

In order to achieve this level of monitoring, the controller monitors the burner every 50 milliseconds to determine whether or not the burner is in operation. If the burner is in operation the controller will store in memory that the burner has been in operation in that time period. The controller keeps a record in memory of how long the burner has been in operation since the last time a putse was generated. Therefore, if the burner is interrupted mid-way through a cycle (between pulses), when the burner is re-started, the amount of time that the burner was in operation since the last pulse was generated is added to the length of time that the burner is currently in operation so that a pulse is generated once the burner 3 has been operational for 23.84 seconds since the last pulse was generated and an accurate record is kept of the amount of fuel that is consumed.

For example, using the embodiment shown above where 10cc of fuel is consumed every 23.84 seconds, if the burner is only operational for 16 seconds after the last pulse was generated and is then stopped mid-way through the cycle, the fact that the burner was in operation for 16 seconds is stored in memory. The next time that the burner is started, the 16 seconds is added on to the timer and a pulse will be generated once the burner is operational for a further 7.84 seconds {16+7.84=23.84 seconds). It will be understood that the burner may have a purge cycle in which a blast of air is used to flush out any un-burnt fuel from the burner prior to burning more fuel. This purge cycle can vary from burner to burner but is often of the order of 12 seconds in length. The purge cycle will be accounted IE 1 Ο Ο 6 6 3 -12for in the calculation of the amount of time that the burner is firing each time a new bum signal is sent to the burner to ensure accurate calculation of the amount of fuel being burnt.

In Figure 4(b), in order to generate the pulse train 73, the nozzle size is set to 1.20 US gal/Hr using control switch 49 and the fuel consumption control switch is set to 1 litre of fuel. In other words, the amount of fuel to be consumed in an hour will be 1000cc of fuel. A pulse will be generated each time the burner has been in operation for 7.93 seconds. Again each pulse indicates that 10cc of fuel has been burnt. In this way, the duration of time between the metering pulses is dependent on the nozzle size and the number of the pulses in a given period will be dependent to an extent on the size of the nozzle. The number of pulses is monitored to determine the amount of fuel consumed.

In other words, every time that the burner has burnt 10cc of fuel, a pulse is generated. A nozzle size of 1.20 US gal/Hr will dispense 10cc of fuel in 7.93 seconds thereby causing a pulse to be generated every 7.93 seconds during continuous operation of the burner. Similarly, a nozzle size of 0.40 US gal/Hr will dispense 10cc of fuel in 23.84 seconds thereby causing a pulse to be generated every 23.84 seconds during continuous operation of the burner. Once the desired limit of fuel has been burnt in a given time period, a signal is sent to shut off the burner for the remainder of the time period.

It is envisaged that it will be preferable to allow the operator of the controller to provide a fuel consumption limit that is more meaningful to them rather than an hourly fuel consumption limit. To that end, according to one aspect of the present invention, the operator of the controller details how much fuel that they wish to use over a thirty day period and from that the controller 5 extrapolates how much fuel can be burnt in each hour of that period. For example, the operator may determine that they wish to burn 250 litres of fuel (approximately a quarter of a standard domestic oil tank) in 30 days. The controller will calculate that the burner can burn 8.33 litres of oil a day over the 30 days or 347cc of fuel each hour for the 30 days. It will be understood that longer or shorter periods than 30 days may be used and 30 days is used hereinafter for convenience only.

In an alternative embodiment, it may be desirable to provide a fixed, pulsed waveform to the burner comprising a plurality of pulses and of a duration dependant on the values of the flow rate specification of the nozzle and the fuel consumption limit set by the operator. This IB 1 0 0663 -13fixed, pulsed waveform may be provided to the burner as a control signal unless interrupted by the thermostat. When the contra! signal has run in its entirety and ail pulses have been counted, the burner will have to wait until the next time period and the next control signal is provided to it in order to operate. This is simply an alternative way of providing a control waveform to the burner.

In the embodiments described above, a strict limit is imposed on the amount of fuel that can be burnt in any one time period, for example an hour. However, practically speaking, it may be advantageous to burn more than the fuel consumption limit amount during certain parts ofthe day and less than the limit amount during other parts ofthe day. Similarly, it may be desirable to have a system in which more fuel is available during an initial start-up phase of the heating installation in order to heat the building from cold with less fuel being required once the building has been brought up to temperature. For example, looking at the fuel consumption of a house on a daily basis, more fuel is usually required during the morning and during the early evening/night whereas less fuel is consumed during the middle ofthe day. Therefore, it is advantageous to have more fuel available when it is needed.

To that end, according to another aspect ofthe present invention, there is provided a fuel bank in which at least a portion of the Kiel bank can be added to the fuel consumption limit for burning in a given time period if it is required. This portion of the fuel bank that may be added to the fuel consumption limit may be a fixed amount of fuel or a fixed proportion of the fuel bank that can be added to the fuel consumption limit. In one embodiment, the amount of fuel available for use in the fue! bank is a fixed proportion of the total amount of the fuel bank and is set on initialisation of the controller 5. Alternatively, the amount of the fuel bank that may be burnt in any one time period is set as a multiple of the fuel consumption limit.

For example, an operator will set an initial limit of 250 litres to be consumed over the next 30 days. The controller will set aside a fixed proportion of that initial limit for use in the fuel bank, for example between 5% and 20% of the initial limit (between 12.5 litres and 50 litres), it has been found that approximately an eighth (12.5%, 31.25 litres) of the initial limit is usually satisfactory. Therefore, 31.25 litres is set aside for use in the fuel bank and the remaining 218.75 litres is for use in setting the hourly fuel consumption limit. In this case, 304cc of fuel will be the hourly fuel consumption limit. The amount of fuel from the fuel bank IE 1 0 066 3 -14that may be used in any one (hourly) time period is usually set as a multiple of the fuel consumption limit. It is envisaged that between 2 and 8 times the initial fuel consumption limit will provide sufficient flexibility and 5 times the fuef consumption limit will usually be satisfactory. In this way, using the above exampie, the total amount of fuel that may be burnt in any (hourly) time period is 1824cc of fuel (the fuel consumption limit, 304cc, added to the available portion of the fuel bank, 1520cc (5 x 304cc)).

The amount of fuel available in the fuel bank is stored in memory and after each hour, the amount of fuel in the fuel bank is updated. If the amount of fuel consumed in the last hour was less than the fuel consumption limit (304cc from the above example) the excess fuei is added to the fuel bank for use later in the 30 day period. At the end of the 30 day period, the fuel bank can be rolled over to the following 30 day period or the saving can be realised as portion of the 30 day fuel limit that was not consumed and represented to the operator as a saving in that 30 day period. As an alternative to the above methodology, it may be preferable to simply allow a fixed percentage of the fuel bank (for example, 20% of the fuel bank) to be burnt in any one time period, in this way however, there will always be an amount left in the fuel bank at the end of each 30 day period.

It is envisaged that the controller and method may provide an adaptive control system in which the pattern of burn requests are monitored over a period of time and thereafter based on the typical bum pattern, the rate at which fuel is removed from the bank can be dynamically adjusted to provide the most effective use of the fuel bank.

Preferably the unit will be lightweight and relatively diminutive in structure having a height of approximately 50 mm, a depth of approximately 75 mm and a length of approximately 150 mm. Furthermore, the device will be provided with a female socket and a male socket so that it may be inserted directly in line with the thermostats in existing systems so that it can be retro-fitted into existing systems. Alternatively, suitable wiring may be provided so that it may be wired up to a system or indeed form part of the burner circuitry. In the embodiment shown, various switches are provided and it will be understood that these could be provided by way of a keypad or other type of user interface and indeed there may be a graphical user interface such as an LCD screen, a touch screen or other like screen that can display current settings to the user and allow the user to program the device using the LCD and/or IE 1 0 0 6 6 3 -15the keypad which may be an alphanumeric keypad, an alphabetic keypad, a pictogram keypad or simply a numeric keypad.

The controller comprises one of a microcontroller, a microcomputer, a microprocessor, a state machine, a custom iC (ASIC), a field programmable gate array (FPGA) and a programmable logic controller (PLC) to perform the control and provide means for performing the various monitoring and control steps. The controller further comprises a memory to store programming, monitoring information and control parameters such as the fuel consumption limit, the volume of fuel available in the bank, the flow rate table and the flow rate specification of the nozzle.

Furthermore, in the embodiment shown, the user is able to set the nozzle size using the control switch 49. However, it will be understood that the nozzle size may be fixed for a particular type of controller 5 and in certain embodiments the nozzle size may not be set by the user. In this way different controllers 5 will be provided for the different nozzle 31 sizes to take this responsibility away from the user. The device can be mains operated, or alternatively a battery supply could be provided.

It will be understood that by incorporating a fuel consumption controller such as that described, the owner of a household or premises can set the number of burn hours that they wish their tank of fuel to last and therefore this gives them some control over the usage and cost of operating the heating installation. This will reduce the likelihood of the user running out of fuel inadvertently and will also allow them to operate their heating installation in a more effective and efficient manner.

Throughout the specification, reference is made to "limiting" or "inhibiting" the operation of the burner. It will be understood that these terms mean that the burner will be prevented from operating during that period. in the specification the terms "comprise, comprises, comprised and comprising or any variation thereof and the terms "include, includes, included and including" are deemed to be totally interchangeable and they should be given the widest possible interpretation.The invention is in no way limited to the embodiment hereinbefore described which may be varied in both construction and detail with the scope of the claims.

Claims

1. -16Claims: {1) A method of controlling a heating installation burner comprising the steps of: 5 setting a fuel consumption limit for the burner for a control time period; monitoring the operation of the burner during the control time period; estimating the fuel consumption of the burner in the control time period 10 using the amount of time that the burner has been firing in the control time period and a flow rate specification of a fuel nozzle through which fuel is supplied to the burner; comparing the estimated fuel consumption for the control time period with 15 the fuel consumption limit for the control time period; and on the estimated fuel consumption for the control time period reaching the fuel consumption limit for the control time period, limiting operation of the burner for the remainder of the control time period.

2. (2) A method as claimed in claim 1 in which the step of setting the fuel consumption limit for the control time period further comprises the steps of: setting a second fuel consumption limit for a second control time period, 25 greater than the fuel consumption limit and the control time period respectively; apportioning some of the second fuel supply limit to a fuel bank; and thereafter calculating the fuel consumption limit for the control time period. IE 1 Ο 0 663 -17(

3. ) A method as claimed in claim 1 or 2 in which the step of comparing the estimated fuel consumption for the control time period with the fuel consumption limit for the control time period comprises the steps of: at the start of a control time period, setting a pulse counter with an integral 5 number of pulses representative of the fuel consumption limit; generating a pulse each time a predetermined amount of fuei has been burnt; and 10 decrementing the pulse counter by one each time a pulse is generated until the pulse counter reaches zero.

4. (4) A controller for a heating installation burner comprising: 15 means to set a fuel consumption volume limit for the burner for a control time period; means to monitor when the burner is firing during the control time period; 20 means to estimate the amount of fuel that has been burnt by the burner in the control time period using the amount of time that the burner has been firing in the control time period and a flow rate specification of a fuel nozzle through which fuel is delivered into the burner; 25 means to compare the estimated amount of fuel that has been burnt in the control time period with the fuei consumption limit for the control time period; and means to limit the operation of the burner for the remainder of the control 30 time period on the amount of fuel estimated to have been burnt in the control time period reaching the fuel consumption limit for the control time period.

5. (5) A household heating installation comprising the controller of claim 4.