GB2437175A

GB2437175A - Water heating system control

Info

Publication number: GB2437175A
Application number: GB0707053A
Authority: GB
Inventors: Santor Singh Gataora; Houghton Ainsworth Gledhill
Original assignee: Gledhill Water Storage Ltd
Current assignee: Gledhill Water Storage Ltd
Priority date: 2006-04-12
Filing date: 2007-04-12
Publication date: 2007-10-17
Also published as: GB0707053D0; GB0607319D0

Abstract

The heating system is connected to a mains water supply 28, capable of being switched between a first operating mode and at least a second mode. The system includes a boiler 12 for heating fluid contained within the heating system, a valve arrangement 32, 34 and 42 for controlling the flow of mains water into the heating system and a control means 26. The control means monitors the condition of the heating system and/or mains supply and controls the valve arrangement so as to selectively control the flow of mains water into the heating system and hence reduce the need for service visits. The control is in response to at least one monitored value such as the pressure of the fluid in the heating system. If the pressure drops below a predetermined level the valve arrangement is opened by the control means to allow mains water to be supplied. The heating system and the control means therefor may also be used in a method of controlling the heating system.

Description

* 2437175 Improvements to Water Heating Systems This invention relates

to water heating systems and in particular to the control of heating systems which are closed off from a mains water supply during normal operation, such as, for example, sealed primary heating systems for domestic use.

Heating systems in their simplest form include a boiler for heating water and connected to a ducting system for transporting the water to its required destination. Domestic wet central heating systems were traditionally fed from a feed and expansion tank at the highest point of the system. The purpose of this tank is to replenish the system if needed and to accommodate expansion when the heating circuit goes from cold to hot. * *

The advent of the combination boiler has encouraged * replacement of the feed and expansion tank with an expansion **.* *..: chamber with a rubber diaphragm which is pressurised with air on one side. This arrangement allows the system to be pressurised as required. As the circuit heats up the associated expansion within the system is accommodated by compression * . of the air within the expansion chamber. Adversely when the system cools down, this allows the air in the chamber to expand.

Such heating systems can thus be isolated from the mains water supply in the form of a closed ioop. The perceived benefits of this arrangement are that the evaporation losses associated with an open feed and expansion tank are avoided, there should be no need to replace water within the system with fresh water which would introduce unwanted oxygen, potentially causing corrosion; and the tank does not need to be positioned at the highest point in the system and so the system can run in, for example, roof spaces in apartments [-lowever these benefits are seldom realised since micro-leaks at fittings within the system allow water to escape in minute quantities, resulting in pressure being lost from the system. In vicw of this problem, it is commonly accepted that there is a need to manually re-charge a sealed boiler system at certain intervals in order to maintain correct operation. At present it is estimated that a maintenance engineer will need to make at least one visit every two years purely to re-pressure the heating system.

Whilst this problem is not unknown, since there is the possibility that the root cause of the problem could be more serious and potentially dangerous, it is generally accepted that such service intervals are necessary.

A heating system cannot be left open to a mains water supply since the mains supply pressure is variable and could exert either *.

excessive or insufficient pressure on the water heating system.

: In addition, until recently, it has been a legal requirement that heating circuits were not to be permanently connected to the mains water supply in order to avoid the risk of backflow 0s*S contamination of mains water. This situation has changed more * * recently and sealed boiler systems can now be permanently connected to a mains water supply, but only using approved valve systems which prevent backflow.

However, despite the introduction of such valves, known as CA valves, it remains a problem that sealed heating systems must be maintained at the required operating pressure. Whilst it is generally straight forward to resolve excessive pressure build up within the system by discharging fluid via the pressure release valve (PRy), this only offers a partial solution to the problem and does not account for losses from the system such that the pressure within the system can over time fall below a level which is adequate for normal operation.

Therefore this invention aims to provide an improved heating system, for which the need to manually inspect and/or service the system is significantly reduced.

According to the present invention there is provided a heating system connected to a mains water supply, said system capable of being switched between a first operating mode and at least a second mode, said system including; a boiler for heating fluid contained within the heating system, at least one valve arrangement for controlling the flow of mains water into said heating system, said valve arrangement connected to a control means, wherein said control means monitors the condition of :. the heating system and/or mains supply and controls the valve :..::: arrangement so as to control the flow of mains water into said heating system in response to at least one monitored value of S...

the heating system. S..

Typically the monitored value is the pressure of the fluid in the heating system and the control means opens the valve arrangement to allow the flow of water into the heating system when the monitored pressure falls below a predetermined level.

Typically water is only allowed to enter the water heating system when the boiler is in a standby mode.

In this manner the correct operating pressure of a heating system can be maintained without the need for manually charging the heating system. By preventing the control means from actuating the valve arrangement to allow mains water to enter the system during operation, the thermal stresses caused by cold water entering a heated system can be avoided. In addition the required pressure rise can be controlled whilst the boiler is in a thermally steady state and is therefore not affected by variations caused by operation. Thus the pressure readings and pressure rise can be effected in a controlled reliable manner.

In one preferred embodiment, the control means additionally records the frequency at which additional water is required to enter the heating system. In addition, or else alternatively, the control means may monitor and/or record any, or any combination of, the volume of water used to top up the system, the rate of pressure loss from the system during use and/or the rate or pressure build up within the system during the top up procedure. By monitoring these values, the control means can determine whether there are allowable pressure losses from the system during normal operation, or else whether there is a more :. serious fault which requires the attention of an engineer. * S *.S.

Preferably the control means is provided with pre-set limits for **..

*..: each of the parameters monitored and/or recorded. In the ** event that any one or more of the parameters fall outside of the pie-determined limits, a fault is registered by the control means. S...

In one embodiment, the control means ceases control of the * * valve arrangement to allow water to enter the heating system upon registering a fault. In this manner the automatic refill function will be terminated so as to indicate that maintenance of the heating system is required.

In one embodiment the control means is arranged to display an indication of the fault and/or the parameters which fall outside the predefined limits so that the fault can be diagnosed. The control means may provide a visual indication of the fault and/or may provide a signal to one or more units located in a different location.

Typically it is possible to manually override and/or reset the control means. Thus the automatic refill function of the control means can be restarted by a service engineer upon clearing a fault. In one embodiment the predeuined limits for the monitored/recorded parameters may be provided as pie-defined factory-set values. Additionally, or else alternatively, the pre-set parameter limits may be entered and/or changed manually based upon the operation characteristics of a particular heating system.

Preferably the control means is provided with one or more algorithms which compares one or more of the recorded parameters and/or the rate of change of those parameters with pre-defined scenarios. Typically the predefined scenarios relate to one or more known problems which can occur with heating systems such as for example faulty expansion vessels and/or unacceptable leakage rates. S... * .

Typically the valve arrangement includes one or more valves *5** : connected between the mains water supply and the boiler. *S.

S

According to one preferred embodiment the valve arrangement *55S (_) includes a combination of two or more valves. Preferably a first * * valve arrangement controls the flow of water to the boiler, which typically takes the form of a solenoid valve. A second valve arrangement may be provided to control the back flow of water from the heating system to the mains water supply. In addition a pressure release valve may be provided to allow discharge of water from the system when the pressure in the system raises above a predefined upper limit.

In one embodiment the second valve arrangement is.. provided upstream of the first valve and a non-return valve is provided downstream of the first valve means for regulating the flow rate into the system may also be provided According to one embodiment, the control means is provided with a first mode of operation for controlling the operation of the system based upon the monitored parameters and a second mode of operation. Preferably the second mode of operation relates to a commissioning mode for when the boiler and/or entire heating system is installed or serviced. Typically the second mode of operation overrides the first mode.

Preferably, in the second, commissioning, mode the control means controls the valve arrangement to allow water to enter the system until a pre-set pressure is reached, following which the control means follows a pre-set sequence of instructions.

Typically these instructions include the cyclic operation of the boiler, a boiler pump and/or the valve arrangement for a predetermined, time period. * *

*S** -, . . I ypically the boiler can be supplied with a commissioning by-Iass or "jumper" fitted to control means in the form of a S..

:. printed circuit board which can be removed by an engineer once the heating system is operational. The second commissioning *..

mode is particular advantageous in that the boiler can be set up, : * * installed and purged through an automated operation which requires little or no manual input.

According to a further aspect of the present invention, there is provided control means for a heating system, the heating system arranged or connection to a mains water supply and including a boiler for heating fluid contained within the heating system, said heating system including a valve arrangement isolating the fluid within the system from the mains water supply during normal operation, wherein control means are arranged to monitor the pressure of the fluid within the system and to control the value arrangement to allow water to flow into the heating system from the mains when the monitored pressure falls below a predetermined level.

According to a yet further aspect, there is provided a method of controlling a heating system.

Preferred embodiments of the invention will now be described in further detail with reference to the accompanying drawings in w hi c h: Figure 1 shows a known sealed heating system according to the

prior art; and,

Figure 2 shows control means for a sealed water heating system according to the present invention. S...

Turning firstly to figure 1, there is shown a closed water heating system 10 according to the prior art. The system 10 includes a *. I boiler 12 which generally receives water to be heated by a pipe *: 14. The heated water leaves the boiler and passes along pipe 16 which provides hot water for heating, typically within a domestic S...

environment. Water then returns to the boiler by conduit 14 so as to form a sealed system, through which the water is pumped by pump 18.

The sealed system is maintained at a pressure above atmospheric pressure and is isolated from the water mains by a manually operable valve or stopcock 20. If the pressuring system falls below the required operating pressure then additional water can be provided from the mains supply by manually opening the valve 20 until the desired pressure is reached. In the event that there is an excessive pressure build up within the system which would normally occur due to there being a fault, a safety relief valve 22 is provided so that water can be discharged to the atmosphere. An expansion vessel is also provided which in use generally remains part-filled with water and which accounts for pressure fluctuations in the system due to heating and cooling of the water.

Turning now to figure 2, there is shown a control arrangement for a sealed system combi boiler according to the present Invention. It will be appreciated that the control means described can equally be applied to a combination boiler system or any other sealed heating system. The control means provides for an automated filling arrangement which avoids the need to manually top up the water within the system from the mains.

The boiler 12 in figure 2 includes a controller 26 in the form of a printed circuit board. It will bc appreciated that the printed circuit board is shown within the boiler 12 for ease oi *::* manufacture, although the PCB 26 may be otherwise located as 1on as it can control the system as described below. (_) *...

The cold water inlet 28 to the boiler provides both mains water to the domestic system as well as a means of filling the primary system. Conduit 30 provides the flow from the boiler within the closed system, such as for example to a central heating system.

The central heating water is returned to the boiler from the central heating system at 31. The combi boiler also provides a hot water supply 33 which can be drawn off by a user separate from the central heating supply 30.

Along with the PCB 26 the control means includes a valve arrangement which comprises a series of devices arranged in the flow path between the cold water inlet 28 and the sealed heating circuit. A back flow prevention device 32 is positioned upstream of a control valve in the form of solenoid valve 34.

The backflow prevention device 32 takes the form of a combination valve often referred to as a CA valve. Typically this device includes two spring-loaded check valves with a central zone therebetween. The valve is regulated by the upstream and downstream pressures such that the upstream valve can close a pressure relief valve for the system and allow the supply df cold water into the heating system. If the upstream pressure drops or else the downstream pressure rises, the valve movement evacuates the central zone so as to allow discharge from the CA valve at 36. The discharge then flows into a common 38 discharge to the outside at atmospheric pressure. Discharge from a pressure release valve may also flow into the common discharge 38.

The solenoid valve 34 is under the control of PCB 26 and can be selectively opened to allow water to enter the heating system :... when the pressure in the system falls bellow normal operational S...

levels. Thus any flow into the system via the CA valve 32 is additionally controlled by the solenoid valve 34. The PCB 26 S...

* may receive pressure readings from one or more pressure S sensors located within the system. For example the PCB may normally receive a pressure reading from a pressure sensor S...

located at one or more different locations within the system.

Whilst it is envisaged that a pressure reading will normally be taken from a sensor which is often located within the boiler housing, it is acknowledged that multiple pressure readings from different points within the system may be of additional use in diagnosing problems which occur such as blockages and/or leaks within the system.

A flow regulator 40 is provided upstream of the solenoid valve 34 and preferably comprises an in-line flow regulator which is located between the solenoid valve and the CA valve 32. In addition to controlling the volume of water entering the system by way of the solenoid valve, the flow regulator allows control of the rate at which water enters the system. A non-return valve 42 is provided downstream of the solenoid valve 34 so as to prevent backflow due to a build up of pressure within the heating system.

In addition it can be seen that a pair of valves 44 are also provide at either side of the above-described valve arrangement.

Thc valves 44 are not intended to be used during normal use and provide an isolating valve arrangement which can be used to shut off the supply from both of the mains and the remainder of the system when access to the valve arrangement is required by a service engineer.

Following is a description of the two proposed operational modes for the control system: S...

In a normal mode of operation the system is only refilled when the boiler is in a standby mode and thus the PCB 26 is * prevented from operating the solenoid valve to open when the *.

* boiler is fired. During the normal mode the boiler controller will log the following parameters associated with the system top up: frec1uency of top up; volume of water used; and rate of pressure build up during top up procedure.

If and when these parameters fall outside pre-set limits, a fault will be registered by the PCB and the automatic refill function will bc terminated. This will prevent exacerbating any problems caused by, for example, excessive leakage from the system. A service engineer will then be able to restart the automatic refill function once any fault has been cleared.

in addition the PCB 26 is provided with algorithms to compare the parameter readings with scenarios which relate to known faults with for example the expansion vessel and/or unacceptable leakage rates within the system.

A commissioning mode can be entered when the boiler is installed or else when the boiler has been switched off for a prolonged period or for servicing. It is intended that the boiler is has a commissioning mode in the software controlling the boiler which can be activated such that the normal mode is overwritten initially upon installation of the boiler in order to provide a specific set of instructions for controlling the boiler during start up.

The commissioning mode is started when power to the boiler is :... switched on. When the power is switched on, the solenoid valve opens and the system begins to fill with water. The solenoid valve remains open whilst the system continues to fill for a pre-set period of time, or else until a pre-set pressure is reached.

* The filling can be interrupted at any time by switching off the main supply to the boiler or by a user/installer interface **.

provided.

After a pre-set filling duration, or else when the system is filled to the prc-set pressure level, a second stage of the commissioning mode is started upon generation of a heat demand. Such a heat demand can be generated by turning on central heating, by turning up a thermostat or else by turning on a hot water tap, etc. When the PCB 26 receives a heat demand the boiler pump will start and will cycle on and off for a preset time period so as to assist purging of the system. During this period, any loss of pressure due to purging is made up by the controlled opening of the solenoid valve 34 as per the normal operation mode. Once the purging time period is complete, the burner can fire upon receipt of a heat demand signal. However the commissioning mode controls the burner to only fire at a minimum rating in order to prevent unnecessary damage to the heat exchanger.

Once the boiler is deemed to be firing consistently, the normal operating mode is selected by switching off the power and removing the commissioning jumper on the controller. The commissioning jumper may be fitted by a service engineer upon servicing the boiler such that the safer commissioning mode is initiated as and when necessary. Whilst the commissioning jumper is a preferred method of initiating the commissioning mode, it is envisaged that other methods of initiating the commissioning mode are possible such as, for example, by initiated the commissioning mode based on the power to the boiler being switched on and in conjunction with a pressure I...

reading from the system.

In view of the foregoing description, the present invention advantageously provides for a control means to allow automated filling which can be applied to either sealed system boilers and I.., also combination boilers whilst allowing for direct connection to a mains water supply.

Claims

Claims 1. A heating system connected to a mains water supply, said

system capable of being switched between a first operating mode and at least a second mode, said system including; a boiler for heating fluid contained within the heating system, at least one valve arrangement for controlling the flow of mains water into said heating system, said valve arrangement connected to a control means, wherein said control means monitors the condition of the heating system and/or mains supply and controls the valve arrangement so as to control the flow of mains water into said heating system in response to at least one monitored value of the heating system.
2. A heating system according to claim I wherein the monitored value is the pressure of the fluid in the heating system and if the pressure drops below a predetermined level the valve arrangement is opened by the control means to allow mains water to be supplied to the heating

. system. a. * S S..CLME: *
3. A heating system according to claim 1 wherein the at least second mode is a commissioning mode.
4. A heating system according to claim 3 wherein the at least second mode is a standby mode.
5. A heating system according to claim I wherein three operating modes are provided, in which the second mode is a commissioning mode and the third mode is a standby mode.
6. A beating system according to any of claims 2-5 wherein the valve arrangement only allows mains water to enter the heating system when said heating system is in a standby mode and/or a commissioning mode.
7. A heating system according to claim I wherein the control means monitors the pressure of the fluid within the heating system and/or the mains supply.
8 A heating system according to claim I wherein the control means actuates the valve arrangement towards the open condition when the pressure of the mains water is higher than that of the fluid in the system.
9. A heating system according to claim I wherein the : . control means has predetermined limit values against which the monitored valves are compared and the comparison is used to determine whether the values are * *1 * acceptable or unacceptable. *.*

*.
10. A heating system according to claim 9 wherein the U...

control means monitors and/or records, any, or any combination of the following parameters; the frequency at which the system water pressure falls below a predetermined level, the frequency at which the mains water enters the heating system, the volume of mains water used to return the heating system water to above the predetermined pressure, the rate at which the heating system water returns to above the predetermined pressure as the mains water is added, and/or the rate of pressure loss from the system.

11. A heating system according to claim 10 wherein the prcdctermined limits of the control means are provided as factory pre-set values.

12. A heating system according to claim 11 wherein the predetermined limits are entered and/or changed manually.

13. A heating system according to claim 10 wherein the control means moves the valve arrangement to the closed condition to prevent mains water from entering the system if any, or any combination, of the monitored parameter valves are determined to be unacceptable.

14. A heating system according to claim 10 wherein the : control means is arranged to display an indication that a S..

S...' fault has occurred if any or any combination of the *:" monitored parameter values are determined to be S...

* unacceptable.

S

15. A heating system according to claim 10 wherein the control means provides at least one audio and/or visual signal to indicate that an unacceptable value has been monitored.

16. A heating system according to claim 15 wherein the at least one signal indicates which value and/or combination of valves are deemed to be unacceptable.

17. A heating system according to claim 10 wherein the control means can be manually overridden and/or reset if any of the monitored parameter values are determined to

be unacceptable.

18. A heating system according to claim 9 wherein the control means has one or more algorithms which compare one or more of the monitored values with one or more predetermined operating scenarios.

19. A heating system according to claim 18 wherein said predetermined operating scenarios relate to one or more faults which are known to develop with heating systems.

20. A heating system according to claim 19 wherein the control means provides at least one audio and/or visual signal to indicate a predetermined operating scenario has occurred.

21 A heating system according to claim I wherein the at : *** least one valve arrangement includes one or more valves and/or valve arrangements connected between the mains water supply and the boiler. S..

22. A heating system according to claim 21 wherein the valve . arrangement includes a combination of two or more valves.

23. A heating system according to claim 22 wherein the valve arrangement includes a solenoid valve controlling the flow of water to the boiler.

24. A heating system according to claim 23 wherein the second valve and/or valve arrangement prevents the back flow of water from the heating system to the mains water supply.

25. A heating system according to claim 24 wherein the valve arrangement includes a pressure release valve to discharge vvater from the system when the pressure in the system rises above a predetermined limit.

26. A heating system according to claim I wherein the first operating mode controls the operation of the system based upon the parameters monitored and/or recorded by the control means, and the second mode controls the operation of the system when the boiler and/or system is installed or serviced.

27. A heating system according to claim 26 wherein the second commissioning mode overrides the first operating mode.

28. A heating system according to claim 27 wherein when in : the second commissioning mode, the control means * ., controls the at least one valve arrangement to allow mains water to enter the system until a predetermined * fluid pressure is reached. I.. *

** 29 A heating system according to claim 28 wherein when the predetermined pressure is reached the control means follows a pre-set sequence of instructions.

30. A heating system according to claim 29 wherein the pre-set sequence of instructions includes the cyclic operation of the boiler, a boiler pump and/or the valve arrangement.

31. A heating system according to claim 30 wherein the cyclic operation of the boiler, a boiler pump and/or the valve arrangement continues for a predetermined period of time.

32. A heating system according to claim 26 wherein the control means is supplied with a commissioning mode bypass/jumper.

33. A heating system according to claim 32 wherein the bypass/jumper is a printed circuit board (PCB).

34. A heating system according to claim 33 wherein the PCB jumper is removed after the boiler and/or system is installed or serviced.

35. A heating system according to claim 34 wherein the PCB jumper is removed by an engineer after the boiler and/or system is installed or serviced.

:. 36 A control means for a heating system connected to a mains water supply, said heating system capable of being switched between a first operating mode and at least a * second mode, said system including; a boiler for heating water contained within the heating system, at least one *.. valve arrangement connected to the heatin system and **** said control means, said control means monitoring the pressure of the fluid within the heating system and controlling the condition of the valve arrangement so as to control the flow of mains water into said heating system with respect to the monitored pressure of the fluid within the system.

37. A method of controlling a heating system connected to a mains water supply, said system including a boiler for heating water contained within the heating system, at least one valve arrangement connected to a control means, said method comprising the steps of monitoring the pressure of the fluid within the heating system, controlling the condition of the valve arrangement through the control means, controlling the flow of mains water into said heating system with respect to the detected pressure of the fluid within the system.

38. A method of controlling a heating system according to claim 36 wherein the heating system is capable of being switched between a first operating mode and at least a second mode.

39. A heating system as hereinbefore described with reference to the accompanying drawings.

40. A method of controlling a heating system as hereinbefore described with reference to the accompanying drawings. * * S... S...

S S... * S S. *S * S *

S