GB2191851A - A device for indicating failure of a boiler - Google Patents

Abstract

A domestic boiler system comprises a boiler 1 adapted to heat a heat transfer fluid flowing through the boiler and means 3 for detecting the temperature of the heat transfer fluid and to provide a signal to an audio and/or visual display device 4 to alert an observer of that device that the temperature of the fluid is below a desired level. The temperature of the fluid flowing through the boiler can be sensed and compared with a desired value so that a remotely located audio and/or visual display is actuated if the temperature sensed is below that required when the boiler is operating. A warning of a malfunctioning or inoperative boiler is thereby given. <IMAGE>

Description

SPECIFICATION Domestic boiler failure device and method The present invention relates to a device and method for sensing the failure of a domestic boiler.

BACKGROUND TO THE INVENTION: Domestic boilers for heating water and/or for providing central heating are usually equipped with a thermostat for cutting out the boiler if the boiler over-heats and with a flame failure device in the case of a gas fired boiler to prevent escape of gas if the boiler should fail to ignite. Of necessity, these are usually located on or immediately adjacent the boiler and are designed to deactivate the boiler in specific circumstances without reference to the boiler operator and give no visual or other display to be observed by the operator that they have been activated.

The operation of the boiler is usually controlled by a timer device set to operate the boiler at desired times throughout the day and night, often in combination with thermostat control devices which switch the boiler on or off according to the water temperature in the hot water storage cylinder or the temperature at one or more selected areas in the building served by the boiler. All these controls assume that when the boiler is supposed to be operating according to the timer and/or thermostat controls it is in fact operating. Where the boiler is located in an area frequently visited by an occupier of the premises, the failure of the boiler to operate will usually be readily noticed and remedial action taken within a short time of the boiler failing to operate.However, when the boiler is located in a remote position not readily observed by the house occupier, for example in a separate boiler room or boiler house or in a cellar as often occurs in larger houses, guest houses or hotels, the failure of the boiler to operate may remain undetected for some time. As a result, the provision of central heating or hot water services will not take place. For a domestic residence this is an inconvenience and results in disruption and inconvenience rather than any financial loss to the house occupier. With a hotel or guest house, the failure to maintain the central heating and/or hot water services for the guests can reflect adversely on the competence of the hotelier and result in loss of customers.

Despite the array of controls presently available for controlling the operation of domestic boilers, there is no system which detects when the boiler has failed to operate in response to those controls and therefore to ensure that this failure is detected before it leads to loss of hot water and/or central heating services. I have now devised a device and method of operating a domestic boiler which reduces this problem.

SUMMARY OF THE INVENTION: Accordingly, the present invention provides a domestic boiler system comprising a boiler adapted to heat a heat transfer fluid flowing the trough the boiler, which system is provided with means for detecting the temperature of the heat transfer fluid and to provide a signal to a display device to alert an observer of that device that the temperature in the fluid is below a desired level.

Preferably, the boiler is one which heats water, the detection device is one which is adapted to sense the temperature of the water in the water pipes adjacent the inlet and/or outlet to the boiler and the display device is located remotely from the boiler to provide an aural and/or visual signal that the water temperature sensed by the detection device is below that which would have been expected if the boiler were operating.

The invention also provides a device for use in the boiler system of the invention, which device comprises a temperature sensing device adapted to be mounted in thermal sensing contact with a conduit carrying the heat transfer fluid to be heated by the boiler and to generate an electrical signal in response to the temperature sensed and to transmit that signal to a display means; and a display device which is adapted to provide an aural and/or visual display in response to the signal from the sensing device.

The invention also provides a method for operating a boiler system for heating a heat transfer fluid, which method comprises sensing the temperature of the fluid flowing through the boiler, comparing that value against a desired value, and actuating a remotely located audio and/or visual display is the temperature sensed is below that required when the boiler is operating.

The term domestic boiler is used herein to denote a heating device having an output of less than 1,000,000 BTU per hour which is used to heat a heat transfer fluid which can be gaseous (as with a ducted hot air central heating system) or a liquid (as with a hot water boiler operated at ambient or super-ambient pressures). The invention is of especial use with hot water boilers operated at ambient temperature and, for convenience, the invention will be described with respect to this form of boiler. Preferably the boiler is gas or oil fired, but the invention can be applied to boilers of all types.

DESCRIPTION OF THE DRA WINGS: To aid understanding of the invention, it will be 20 described with respect to the preferred form thereof shown in the accompanying drawing, which is a block diagram of the boiler system.

DESCRIPTION OF THE PREFERRED EMBODI MENT: The boiler system comprises a boiler 1 located at a location visually and aurally separated from the normally occupied portion of the building, as indicated schematically by the dotted line. Thus, the boiler can be located in an outhouse or boiler room or in a cellar not normally visited by the occupants of the building. As is customary, two or more boilers can be used to supply the total heat requirements of the building to ensure that at least part of the total load is supplied in the event of breakdown or service of any one of the boilers. In this case the total output of the boilers may exceed the 1,000,000 BTU per hour limit specified above.

The boiler 1 heats water which is pumped or otherwise caused to flow through a primary circuit 2. This can be merely the central heating circuit of the building or can incorporate a heat exchanger or calorifier to enable domestic hot water to be heated indirectly. The circuit 2 and the calorifier can incorporate control valves to direct and shut off the flow of water as required in response to conventional thermostatic controls.

The temperature of the water flowing through the boiler is monitored by a suitable sensor 3. Preferably, the temperature is monitored on the outlet side of the boiler by a suitable sensor mounted in thermal contact on the pipework of the primary circuit 2 within 0.1 to 2 metres of the boiler outlet so as to give a direct indication of the water temperature reached within the boiler and to reduce the effects of heat losses to the environment.

However, the sensor 3 can be positioned elsewhere on the circuit 2, provided that allowance is made for the heat losses from the pipe and other factors due to the location of the sensor which could affect the temperature sensed by the sensor.

The sensor 3 can be one which incorporates means for giving an electrical signal which varies with the temperature to achieve a continuously variable signal from the sensor.

Alternatively, the sensor can be a bimetallic strip or similar sensor which actuates a mechanical flip flop or other switch when a given temperature is passed. In the latter case the temperature at which the sensor actuates the switch can be preset to any desired level at the sensor. Where a continuous signal is emitted from the sensor, this signal can be compared against that for the desired temperature at which the sensor should actuate the visual or audio display. This comparison can be achieved at the sensor or at the display unit using known techniques and apparatus.

In a particulary preferred form of the invention, the sensor 3 is provided by a conventional bimetallic sensor as used in a hot water storage cylinder thermostat, and this is strapped onto the outlet pipe from the boiler to achieve the necessary thermal contact between the water flowing in the pipe and the sensor.

The sensor for use in the present invention will normally operate electrically and can be connected in with the electrical power supply serving the boiler control system. However, it is preferred to provide the sensor either with an independant power supply and/or with a battery back-up power supply so that the sensor will continue to operate in the event of a power failure to the boiler.

The sensor detects when the water in the boiler has been heated to the desired temperature corresponding to that which would be expected when the boiler is operating. If the water does not reach the desired temperature, then the sensor acutates the display device.

Where the boiler is operated intermittently, there will be times at which the boiler is deliberately not operated. Such operation will usually be in response to a timer or thermost control and the sensor 3 should be interlinked with such controls in known manner to avoid actuation of the display during periods when the boiler is intentionally switched off. Furthermore, there will usually be a time lag between initial start up of the boiler and the water reaching the desired operating temperature. It is therefore desired that the sensor, its control system or the display device incorporate a time delay so that erroneous alarms are not given during start up of the boiler.

The sensor actuates a display device 4 which alerts an occupier of the building that the boiler has not reached its operating temperature when this would be expected. The display device can be selected from a wide range of commercially available devices and is located at any suitable position in the building where it is likely to be observed frequently by occupants of the building. Thus, the sensor can be located alongside the time and other controls for the boiler in a kitchen, hallway or other room some distance from the boiler. Alternatively, the display device can incorporate a noise generator of some kind to provide an audio signal to the occupier that the boiler should be inspected. If desired, the display device can be incorporated into the timer controls for the boiler.

In operation, the sensor and/or the display system are set so that the sensor actuates the display device at a suitable temperature.

This temperature corresponds to that which the water should have at the point in the circuit at which the sensor is mounted. The exact value will depend upon, inter alia, the position of the sensor, the load which the boiler is actually serving at that moment and the ambient temperature. On cold days and shortly after start-up, the temperature of the water may be lower than that which is observed at the sensor on a warm day when the boiler is serving only a light load. The temper ature at which the sensor is set to actuate the display device must therefore accommodate such fluctuations. If the sensor is set to actuate the display device at a low temperature, the inertia due to the thermal capacity of the system may require a considerable time period after failure of the boiler before the sensor actuates the display device.We therefore prefer that the sensor actuate the display device at a temperature of from 5 to 30"C below that temperature corresponding to the water temperature when the boiler is serving its maximum load. If desired, the temperature of actuation can be interlinked with the thermostat control on the boiler so that during summer months when the boiler thermostat may be set lower than during winter months, the system of the invention is automatically adjusted with the thermostat.

The system of the invention provides a simple and effective means for establishing that a boiler is actually operating and heating water at those times when it should be. The system can be constructed using commercially available components and can readily be incorporated into the overall control system for the boiler to provide a single control box or panel from which an occupier of the building served by the boiler can determine the state of the boiler operation from a location removed from the boiler itself. The system can readily be fitted to existing boiler systems as well as to new installations.

The system has been described above in terms of mounting a sensor at or adjacent the outlet to the boiler. However, the sensor can be mounted elsewhere as indicated above.

We have found that advantages can be obtained when a sensor is mounted at both the outlet and inlet to the boiler. In this way a comparison can be made between the inlet and outlet temperatures for the boiler water.

From a knowledge of the boiler, and of the design and load of the system it serves, it is possible to determine the maximum difference between the inlet and outlet temperatures which should be encountered during normal operation. The sensors can then be set so that the display device is actuated if this difference is exceeded. This method of operation reduces the need to accommodate fluctuations in ambient conditions and the setting of the boiler thermostat.

In addition to actuating the display device when the boiler fails to operate, the device will also be actuated if the boiler is operating inefficiently and cannot maintain the required temperature, for example when the boiler flue outlet is obstructed or if the boiler requires a service. The invention can thus also be used to indicate a fall off in the operating efficiency of the boiler before actual failure of the boiler occurs.

Claims (8)

1. A domestic boiler system comprising a boiler adapted to heat a heat transfer fluid flowing through the boiler, which system is provided with means for detecting the temperature of the heat transfer fluid and to provide a signal to an audio and/or visual display device to alert an observer of that device that the temperature in the fluid is below a desired level.

2. A a device for use in the boiler system of claim 1, which device comprises a temperature sensing device adapted to be mounted in thermal sensing contact with a conduit carrying the heat transfer fluid to be heated by the boiler and to generate an electrical signal in response to the temperature sensed and to transmit that signal to a display means; and a display device which is adapted to provide an aural and/or visual display in response to the signal from the sensing device.

3. A method for operating a boiler system for heating a heat transfer fluid, which method comprises sensing the temperature of the fluid flowing through the boiler, comparing that value against a desired value, and actuating a remotely located audio and/or visual display if the temperature sensed is below that required when te boiler is operating.

4. A system, device or method as claimed in any one of claims 1 to 3 1 wherein the heat transfer fluid is water.

5. A system or method as claimed in either of claims 1 or 3 wherein the detection device is one which is adapted to sense the temperature of the heat exchange fluid in the fluid conduits leading out of the boiler, and the display device is located remotely from the boiler.

6. A system, device or method as claimed in any oen of the preceding claims wherein there is provided a time delay means so that erroneous alarms are not given during start up of the boiler.

7. A system or method as claimed in any one of the preceding claims wherein a sensor is mounted at both the inlet and the outlet to the boiler whereby the difference between the fluid inlet and outlet temperatures can be monitored and the display device actuated if the difference exceeds a predetermined amount.

8. A system, device or method substantially as hereinbefore described with respect to the accompanying drawing.