METHOD AND SYSTEM FOR MANAGING A RESERVOIR OF WATER REQUIRING RECIRCULATION AT TIME INTERVALS

Abstract

A method of managing a reservoir of water having a recirculating arrangement for recirculating water at frequent time intervals is disclosed. The method includes starting a productive recirculation of water within the reservoir by means of the recirculating pump, and sensing control parameter/s relating to the quality of water that are selected from: a level of disinfectant, a pH level, a water turbidity level, or a biological count level. The productive recirculation of water by the recirculating pump is continued until each sensed control parameter has reached its target level in the water. In a power saving management mode the productive recirculation of water by the recirculating arrangement is stopped when each sensed control parameter has reached its target level. Instead in a minimum run time mode the productive recirculation is only stopped when this minimum run time has been completed and each sensed control parameter has reached its target level. A management system for installation on a reservoir to carry out the method is also disclosed.

Description

FIELD OF THE DISCLOSURE

This disclosure relates to a method for managing a reservoir of water requiring recirculation at time intervals. This disclosure also relates to a system for managing a reservoir requiring recirculation at time intervals. The disclosure also extends to a reservoir of water including such a system for managing the reservoir.

This disclosure relates particularly but not exclusively to a method of managing a reservoir of water within which humans can be immersed in use, which requires periodic or even frequent turnover of the water therein. In particular the disclosure relates to a reservoir of water that is a swimming pool. It will therefore be convenient to describe the disclosure with reference to this example application. However at the same time it must be recognized that the disclosure is capable of broader application. For example the disclosure could be applied to a reservoir of water used by humans such as a spa or a hot tub. It could also be applied to a reservoir of water that does not receive humans therein in the normal course of its use such as for example part of a water ride at an amusement park or a water feature such as a fountain or a water fall. It could also be applied to a water storage tank having a recirculating loop, or a fish tank or an aquarium.

In this specification the term of ‘reservoir of water’ shall be understood to mean a containment structure holding a body of water. It will often have an open top but it does not need to have an open top. It includes both reservoirs intended to receive human beings such as a swimming pool and reservoirs that are not intended to receive human beings.

In this specification the term ‘disinfectant’ shall be understood to include all substances or agents that can be used for the disinfection of water to make it suitable for receiving human beings therein. The term ‘disinfectant’ shall be understood to include sanitising agents. The term ‘disinfectant’ shall also be understood to include free halogens such as chlorine and bromine as well as agents used for advanced oxidation processes including ozone, hydrogen peroxide oxygen and air, but it is not to be limited to these compounds.

Further in this specification the term ‘disinfectant dosing arrangement’ shall be interpreted broadly and shall be understood to include all modes of achieving the addition of disinfectant such as free halogen, e.g. chlorine, to a body of water. For example it shall include a chlorinator for generating free chlorine from a body of salt containing water by the electrolysis of salt within the water as well as dosing arrangements containing dosing pumps for dosing liquid and solid disinfectant into the body of water.

In this specification the term ‘productive recirculation’ shall be understood to be a recirculation that has a suitable flow rate for treating the water in the reservoir. That is the flow rate of the water is sufficient for dosing with disinfectant to be carried out and also for acid or alkali to be safely and efficaciously dosed into the recirculating water. It shall also be understood to be a flow rate that is suitable for being used to drive a suction style automatic pool cleaning device.

In this specification the term ‘trickle recirculation’ shall be understood to be a level of flow that is lower than that constituting productive circulation and which is below that suitable for dosing the water with disinfectant and acid or alkali. Also it is below the flow rate that is suitable for the operation of a pool cleaning device.

In this specification the term ‘control parameter’ shall be understood to refer to a parameter that is sensed and controlled as part of a control method. Typically such a control parameter would be influenced by a controller, e.g. exerting a control action on the control parameter.

BACKGROUND TO THE DISCLOSURE

Water reservoirs that are in the form of swimming pools are widespread in many countries of the world, and particularly in those countries having warmer climates. Each swimming pool comprises a containment structure having an open top that holds a body of water having an operatively upper water surface that is in contact with the air. Swimming pools receive human beings in use and it is common for human beings using a swimming pool to immerse themselves or submerge themselves in the water. As a result the eyes, ears, nose and mouth of swimming pool users regularly come into contact with the swimming pool water in use.

Consequently swimming pools have to be carefully managed to avoid the transmission of bacteria and viruses to users through the medium of the water in the swimming pool. This is particularly the case where water can form an aerosol such as in a water feature or a fountain. An outdoor swimming pool is typically open to the environment and is open to chronic sources of contamination such as human bodies, animals, airborne dust, insects, ornamental plant and tree debris, bird faeces, and other biological matter that is present in the environment. E. coli bacteria is a major source of contamination in swimming pools. Further cryptosporidium and Giardia are two other pathogens that are also a significant source of contamination of swimming pool water. Further water is also considered to be an agent for the transmission of bacteria that causes Legionnaires disease. It will readily be apparent that bathers will be subjected to have prolonged exposure to any water borne bacteria or viruses in the water in the swimming pool when they are swimming.

Part of the treatment of water in a swimming pool involves turning over the otherwise static or stagnant water in a swimming pool. Current standards require an amount of water corresponding to the volume of water within a swimming pool to be turned over or recirculated through a recirculating loop of the swimming pool each day. A further part of the treatment is that water within the swimming pool must be periodically tested and treated with effective treatment chemicals such as disinfectant and bactericidal chemicals, in order to provide a safe bathing environment.

One known method of chemical treatment of a swimming pool is to dose a halogen into the water. The halogen is dosed to a level of 0.1 ppm to 10.0 ppm of free halogen concentration which provides a strong oxidising action which is effective in killing bacteria. Chlorine is the most common halogen used for this type of water treatment although bromine is also used. Hypochlorous acid is recognised as the most effective disinfectant of the chlorine based compounds. The pool industry typically recommends that a concentration of between 1.0 and 3.0 ppm be maintained in the swimming pool to provide for effective sanitation.

Each swimming pool has a recirculating arrangement which typically includes a recirculating conduit and a recirculating pump which is mounted on the recirculating conduit. The pump draws water from the reservoir into the pump and pumps it through the recirculating conduit and then back into the swimming pool. The recirculating arrangement also includes a water filter that is coupled into the recirculating conduit downstream of the pump. The recirculation of the water through the recirculating conduit and through the water filter removes suspended solids from the water and improves the clarity of the water.

The recirculating pump is typically switched on at a certain time of the day, and it runs for a set pump run time each day, and then it switches off. The start time for recirculation and the length of time for which the water is recirculated is set by the user on a clock. A typical swimming pool might have a pump run time of four to eight hours a day during which the pump draws water from the reservoir and then pumps it through the water filter and back into the reservoir. As a crude approximation a pump run time should be set so as to turn over or circulate a volume of water corresponding to the volume of water in the reservoir each day. Typically each pool may operate on a set pump run time of four to eight hours a day. Thus the pump run time is a set or fixed time that is not determined by the quality of the water at the end of the pump run time. The pump runs for the fixed pump run time and then switches off regardless of the water quality at the end of the pump run time.

Further when managing a swimming pool, a disinfectant needs to be added to the water at least periodically to kill or neutralise pathogens and organisms within the body of water. Other chemicals such as acid, buffer, and stabiliser may also need to be added to the water at least periodically. The act of adding disinfectant to the water in most instances has the effect of raising the pH of the body of water. The increase in pH substantially reduces the efficacy of the disinfectant and accordingly to counteract this it is highly desirable that the pH be reduced by the addition of acid to the body of water, either during or after dosing with disinfectant to maintain the pH within pH limits at which the disinfectant is efficacious.

It will further be appreciated that water in a swimming pool comes into contact with the bodies of swimmers using the swimming pool, and in particular it comes into contact with the skin and eyes of said users. Accordingly for this reason as well it is highly desirable that the pH of water be maintained overall within certain pH limits so that it does not cause discomfort to a user's skin.

Disinfectant has been traditionally delivered to the body of water in a number of ways, including:

• • manual addition of a fixed volume of disinfectant on a periodic basis such as a daily or weekly basis;
  • manual measurement of chlorine levels in the water followed by a manual addition of a certain amount of disinfectant based on the extent of deviation of the chlorine level from a target level or set point (factoring in the volume of water in the pool);

dosing of a disinfectant into the pool by means of an electrolytic cell that operates when operating in filtration mode; and

• • dosing of a disinfectant into the pool through a dosing system, e.g. when the filtration mode is operating.

The acid has similarly traditionally been delivered to the body of water in the following ways, including: manual addition of a calculate or determined volume of acid on a periodic basis, e.g. a daily, weekly or a monthly basis;

• • manual measurement of pH followed by addition of a certain amount of acid based on the extent of deviation of pH from a target level or set point pH and the volume of water in the pool; and
  • dosing acid into the pool through a dosing system, e.g. when operating in the filtration mode.

From the above discussion it is clear that there is scope to improve the management of swimming pools to effect appropriate turnover of water in the pool and to maintain effective levels of disinfectant and pH within the pool. In particular there is scope to reduce the amount of energy used to properly manage a pool. In an era of high energy costs and an ongoing imperative to reduce energy consumption it is clear that the achievement of energy savings in the management of swimming pools would be significant. Any significant breakthrough in this area would have benefits for individual pool owners in terms of the better management of their pools. It would also have benefits for the public at large in terms of reduced overall energy consumption and reduced greenhouse gas emissions.

SUMMARY OF THE DISCLOSURE

According to one aspect of this disclosure there is provided a method of managing a reservoir of water that has a recirculating arrangement for recirculating water within the reservoir at time intervals, the method including:

• • starting a productive recirculation of water within the reservoir by means of the recirculating arrangement;
  • sensing at least one control parameter relating to the quality of water within the reservoir; and
  • continuing the productive recirculation of water by the recirculating arrangement at least until each sensed control parameter has been managed in such a way that the level of that control parameter in the water within the reservoir will reach a certain level.

The method may include stopping the productive recirculation of water by the recirculating arrangement when each sensed control parameter has been managed such that the control parameter will reach a certain level. This may conveniently be referred to as power saving management mode.

Instead the method may include setting the productive recirculation to run for a minimum productive recirculation time, and stopping the productive recirculation only when this minimum productive recirculation run time has been met in addition to each sensed control parameter being managed such that it will reach its certain level in the water. This may conveniently be referred to as the minimum run time management mode.

The sensing of the at least one parameter may occur before the recirculation arrangement is started or the sensing may occur after the recirculation arrangement is started. Thus it is not necessary to sense after the productive recirculation is started.

The method may include either stopping the recirculation of water completely when the productive recirculation is stopped, or reducing the recirculation of water to a trickle recirculation, when the productive recirculation is stopped. The reduction of the recirculation to a trickle recirculation may be utilised when certain pumps, e.g. variable speed pumps with power saving features are used for recirculation.

The certain level of each sensed control parameter at which the productive recirculation is stopped may be a target level of the sensed control parameter.

Sensing at least one control parameter relating to the quality of water may include sensing the level of disinfectant within the water, and the method may include continuing the productive circulation, at least until, the level of disinfectant has reached its target level. Sensing the level of disinfectant within the water may include sensing the level of free halogen within the water utilising an ORP probe. The ORP probe senses an electrical signal in mV level which can then be interpreted as a level of free halogen expressed in ppm of free halogen within the water. Instead the sensing of disinfectant may be carried out with a ppm probe or by a reagent test.

Sensing at least one control parameter relating to the quality of water may include sensing the level of acid or alkali within the water by measuring the pH level of the water, and the method may include continuing the productive recirculation, at least until, the level of acid or alkali has reached its target level.

Sensing at least one control parameter relating to the quality of water may include sensing the level of clarity or turbidity of the water, and method may include continuing the productive recirculation, at least until, the level of clarity or turbidity has reached a certain level. The certain level of turbidity may comprise a turbidity falling with a certain range of turbidity. In managing a reservoir such as a swimming pool a low level of turbidity is desired.

Yet further sensing at least one control parameter relating to the quality of water may include sensing the biological count within the water. This may include a measure of the count of biological organisms such as viruses, bacteria and other pathogens within the water.

The method may include continuing the productive recirculation, at least until, the biological count has been reduced to a target level.

The method may include sensing two or more different control parameters relating to the quality of water within the reservoir, and continuing the productive recirculation at least until each of the two or more sensed control parameters has reached a certain level, e.g. their target levels.

In particular the method may include sensing one control parameter that is the level of disinfectant, and another control parameter that is the pH level or level of acid or alkali in the water, and continuing the productive recirculation at least until the level of disinfectant and the pH level or level of acid or alkali has reached its target levels.

The method may further include sensing the level of turbidity in the water and continuing the productive recirculation at least until the level of turbidity has also reached its certain level. Thus in this example the productive circulation continues at least until the levels of disinfectant, acid or alkali and also turbidity reaches the target levels.

In another example of this other form of the disclosure the method may include sensing one parameter that is the level of clarity or turbidity within the water and another parameter that is the level of disinfectant in the water, and stopping the productive recirculation of water only when each of these parameters has reached their target level.

Over and above sensing the level of disinfectant within the water, the method may also include: monitoring the level of the sensed disinfectant level; and adding disinfectant to the water in response to the sensed level to promote adjustment of the sensed level towards the target level of disinfectant, during the productive recirculation of water from the reservoir. Thus the method also includes controlling the level of disinfectant within the water during the productive recirculation of the water by the recirculating arrangement.

In particular the disinfectant may be added to the water by a disinfectant dosing arrangement that includes an electrolytic cell for electrolysing a halogen containing salt to generate free halogen in the water or a dosing pump having a dosing line for dosing a halogen containing substance into the body of water.

The method may further include ceasing the dosing of disinfectant into the water, during the productive recirculation, if the water has been managed such that the target level of disinfectant will be reached within the water in the reservoir, before the productive recirculation is stopped. Thus if the level of disinfectant is managed to a point where the target level will be reached, before the productive recirculation is ceased, the disinfectant dosing arrangement stops dosing. In this case the productive recirculation continues until each of the sensed parameters reaches their certain levels, and when this has occurred the productive recirculation stops.

The method may further include monitoring the sensed pH level; and adding acid or alkali to the water in response to the sensed pH level to promote adjustment of the sensed pH level towards the target pH level, during the productive recirculation of water from the reservoir.

The acid or alkali may be added to the water by an acid or alkali dosing arrangement that includes a dosing pump, and a dosing line for dosing acid or alkali into the water.

The method may further include ceasing the dosing of acid or alkali into the water, during the productive recirculation thereof before the productive recirculation is stopped, if the water has been managed such that the target level of acid or alkali will be attained before the productive recirculation is ceased. Thus if the acid or alkali is managed to a point where the target level will be reached, before the productive recirculation is ceased, the acid or alkali dosing arrangement stops dosing. In this case the productive recirculation continues until each of the sensed parameters reaches their certain levels, thereby meeting the criteria for the productive recirculation to stop.

The recirculating arrangement may comprise a recirculating conduit and a recirculating pump coupled in line with the recirculating conduit. Starting the productive recirculation of water by the recirculating arrangement may include switching on the recirculating pump. Correspondingly stopping the productive recirculation of water by the recirculating arrangement may include switching off the pump or substantially reducing the volumetric throughput of the pump.

Switching the recirculating arrangement on to start productive recirculation of water within the reservoir may be initiated at one or more times in a given time period. The given time period could be a day or a week or a month. Further the times may be set times that are entered by a user or times that are entered during manufacture or times that are chosen by the controller and entered. In one example the recirculating arrangement is switched on to initiate recirculation twice a day at two specific times during the day and this pattern is repeated every day. In another example the recirculating arrangement is switched on to initiate recirculation twice a week at two specific times during the week and this pattern is then repeated at the same times every week.

Instead switching the recirculating arrangement on to start productive recirculation of water within the reservoir may be initiated once a certain period of time has elapsed since the recirculating arrangement was previously switched on. In particular the recirculating arrangement may be switched on after a set number of hours has elapsed since it was previously switched on. For example the recirculating arrangement may be switched on at 6 hour or one hour intervals.

The reservoir of water may be a reservoir within which people immerse themselves during its use. In one example form the reservoir of water may be a swimming pool.

According to another aspect of this disclosure there is provided a method of managing a reservoir of water that has a recirculating arrangement for recirculating water within the reservoir at frequent time intervals, the method including:

• • starting a productive recirculation of water within the reservoir by means of the recirculating arrangement; and
  • sensing one control parameter that is the level of disinfectant and sensing another control parameter that is the pH of the water, and continuing the productive circulation at least until the level of disinfectant has reached its target level and the pH level has reached its target level, and then stopping the productive recirculation by switching off the recirculation of water from the reservoir.

The level of disinfectant may be sensed by an ORP probe and the pH level may be sensed by a pH probe, and the method may include dosing disinfectant and acid into the water to adjust the disinfectant and pH levels to their target levels.

The method may include any one or more of the features of the method defined in the first preceding aspect of the disclosure.

According to another aspect of this disclosure there is provided a method of managing a reservoir of water that has a recirculating arrangement for recirculating water within the reservoir at time intervals, the method including:

• • starting a productive recirculation of water within the reservoir by means of the recirculating arrangement;
  • sensing at least one control parameter relating to the quality of water within the reservoir;
  • setting the productive recirculation of water to run for a minimum productive recirculation run time; and
  • stopping the productive recirculation of water by the recirculating arrangement when the minimum productive recirculation run time has elapsed, and when the sensed control parameter has been managed in such a way that the level of that control parameter in the water within the reservoir will reach a certain level.

The minimum productive recirculation run time may be set by a user. For example the minimum productive recirculation run time may be 1 hour or it may be 30 minutes. Further the method may include setting different minimum productive recirculation run times for different times of the year. By setting a minimum productive recirculation run time it is ensured that the productive recirculation will continue for a certain length of time for sufficient turnover of water within the reservoir to occur. This is particularly the case when the productive recirculation is being stopped when the water reaches certain disinfectant and pH levels, e.g. chemical balance, whereas the water clarity or turbidity is not being used to influence when the productive recirculation is stopped. Further by setting a minimum productive recirculation run time it is ensured that the productive recirculation will continue for a certain length of time that enables an automatic cleaning device to cover an interior surface of the reservoir.

The method may include sensing two or more different control parameters relating to the quality of water within the reservoir, and stopping the productive recirculation of the water when each of the two or more monitored control parameters has reached their target level, and when the minimum productive recirculation run time has elapsed.

The method may include sensing one control parameter that is the level of disinfectant and sensing another control parameter that is the pH level or level of acid/alkali in the water, and stopping the productive recirculation of the water when each of these control parameters has reached their target level and when the minimum productive recirculation run time has elapsed.

According to another aspect of this disclosure there is provided a method of managing a reservoir of water that has a recirculating arrangement for recirculating water within the reservoir at frequent time intervals, the method including:

• • starting the recirculating arrangement to recirculate water within the reservoir, sensing at least one control parameter relating to the quality of water within the reservoir; and
  • stopping the recirculation of water by the recirculating arrangement when each sensed control parameter has reached a certain level.

The method may include any one or more of the features of the method defined in the first preceding aspect of the disclosure.

According to another aspect of this disclosure there is provided a system for managing a reservoir of water having a recirculating arrangement for productively recirculating water within the reservoir at spaced time intervals, the system including:

• • a sensing arrangement for sensing at least one control parameter relating to the quality of water within the reservoir and comparing it with a certain level for, each sensed control parameter; and
  • a controller for starting productive recirculation with the recirculating arrangement to recirculate water from the reservoir of water through the recirculation arrangement and continuing with the productive recirculation until each sensed control parameter has been managed in such a way that will reach a certain level in the water in the reservoir.

The sensing arrangement may include a disinfectant sensor for sensing the level of disinfectant in the water that is operatively coupled to the controller.

The system may further include a disinfectant dosing arrangement for dosing disinfectant into water being recirculated by the recirculating arrangement, and the disinfectant dosing arrangement may be operatively coupled to the controller such that the controller can control the dosing of disinfectant by the dosing arrangement.

The disinfectant dosing arrangement may include a disinfectant dosing pump operatively connected to a tank of disinfectant, or a chlorinator that is mounted on the recirculating arrangement that is coupled to a source of electrical energy for electrolysing salt within the water to form a disinfectant that is free chlorine.

The sensing arrangement may include a pH sensor for sensing the level of pH in the water that is operatively coupled to the controller.

The system may further include an acid or alkali dosing arrangement for dosing acid or alkali into water being recirculated by the recirculating arrangement, the acid or alkali dosing arrangement being operatively coupled to the controller such that the controller can control the dosing of acid or alkali by the dosing arrangement. The acid or alkali dosing arrangement may include an acid or alkali dosing pump operatively connected to a tank of acid or alkali.

The sensing arrangement may include at least one turbidity sensor for sensing the level of turbidity in the water, and wherein the turbidity sensor is operatively coupled to the controller. The turbidity sensor may operate to sense the level of turbidity by passing a beam of light through a container containing the water and observing the extent to which particles within the water influence the beam of flight.

The controller may include means for operatively connecting each of the sensors to the controller such that the controller can receive sensing signals from each of the sensors. The operative connecting means may comprise hard wiring.

The controller may include means for operatively connecting the disinfectant and acid or alkali dosing arrangements to the controller such that the controller can control the dosing of disinfectant and acid or alkali by the dosing arrangement. The operative connecting means may comprise hard wiring.

The system may have operating instructions entered into the controller or programmed into the controller to start the recirculating arrangement at one or more set start times each day. Instead the system may have operating instructions entered into the controller or programmed into the controller to start the recirculating arrangement once a fixed period of time has elapsed since after the recirculating arrangement was previously started.

According to another aspect of the disclosure there is provided a reservoir of water including:

• • a containment structure containing water;
  • a recirculating arrangement for periodically recirculating the water in the containment structure; and
  • a system for managing the reservoir of water as defined the preceding aspect of the disclosure.

The recirculating arrangement may include a recirculating conduit, a recirculating pump coupled in line with the recirculating conduit, and a water filter coupled to the recirculating conduit either upstream or downstream of the recirculating pump.

The water in the containment structure may have a water surface that is in contact with air above the water and the containment structure may have an open top, and in particular the reservoir of water may be a swimming pool.

In particular the management system on the reservoir may include any one or more of the optional or preferred features of the management system defined in the preceding aspect of the disclosure. In particular the system may include a disinfectant sensor in the sensing and dosing manifold for sensing the level of disinfectant in water passing the disinfectant sensor in the recirculating conduit. Further the system may include a pH sensor in the sensing and dosing manifold for sensing the pH level of water passing the pH sensor in the recirculating conduit.

The system may include a disinfectant dosing arrangement and the disinfectant dosing arrangement may dose disinfectant into the recirculating conduit, e.g. the sensing and dosing manifold on the recirculating conduit, and downstream of the disinfectant sensor.

The system may include an acid or alkali dosing arrangement and the acid or alkali dosing arrangement may dose acid or alkali into the recirculating conduit, e.g. the sensing and dosing manifold on the recirculating conduit, and downstream of the acid or alkali sensor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A system for managing a reservoir of water and a method for managing a reservoir of water requiring recirculation at spaced time intervals in accordance with the disclosure may manifest itself in a variety of forms. It will be convenient to hereinafter describe several embodiments of the disclosure in detail with reference to the accompanying drawings. The purpose of providing this detailed description is to instruct persons having an interest in the subject matter of the disclosure how to carry the disclosure into practical effect. However it is to be clearly understood that the specific nature of this detailed description does not supersede the generality of the preceding broad description. In the drawings:

FIG. 1 is a schematic flow sheet of a reservoir of water and a system for managing the reservoir of water operatively installed on the water reservoir in accordance with one embodiment of the disclosure;

FIG. 2 is a schematic flow sheet of a reservoir of water and a system for managing the reservoir of water operatively installed on the water reservoir that is a variation on the embodiment in FIG. 1;

FIG. 3 is a schematic flow sheet of a reservoir of water and a system for managing the reservoir of water operatively installed on the water reservoir in accordance with another embodiment of the disclosure;

FIG. 4 is a schematic flow sheet of a reservoir of water and a system for managing the reservoir of water operatively installed on the water reservoir that is a variation on the embodiment in FIG. 3; and

FIG. 5 is a schematic flow sheet of a reservoir of water and a system for managing the reservoir of water operatively installed on the water reservoir in accordance with yet another embodiment of the disclosure.

In FIG. 1 reference numeral 10 refers generally to a system for managing a reservoir of water that is a swimming pool in accordance with one embodiment of the disclosure.

The management system 10 comprises broadly an ORP sensor 12 for sensing the level of chlorine disinfectant in the water and a pH sensor 14 for sensing the pH of the water. The management system 10 also includes a controller indicated generally by the reference numeral 16 and hard wires 18 operatively connecting the controller 16 to each of the ORP sensor 12 and the pH sensor 14. The system 10 also includes a hard wire 19 for electrically connecting the controller 16 to a mains electrical supply whereby to supply it with electrical power.

The management system 10 also includes a disinfectant dosing arrangement 20 for dosing disinfectant into the water at the direction of the controller 16 in response to the disinfectant levels sensed by the ORP sensor 12. The controller 16 compares the levels of disinfectant sensed by the ORP sensor 12 with a desired or target level of disinfectant within the water and doses through the arrangement 20 with disinfectant accordingly.

The disinfectant dosing arrangement 20 comprises a supply tank 22 of disinfectant that is operatively coupled to a dosing pump 24 which has dosing pipeline 26 which discharges through a dosing point into water from the reservoir. The dosing pump 24 is operatively coupled to the controller 16 by means of hard wiring 27 which extends from the controller 16 to the pump 24.

The management system 10 also includes a further dosing arrangement 30 for dosing acid or alkali, and more typically acid, into the water in response to the pH level sensed by the controller 16 and a desired or target pH level within the water. The acid dosing arrangement 30 comprises a supply tank of acid 32 that is operatively coupled to an acid dosing pump 34 which has a dosing pipeline 36 that discharges into the water from the reservoir. The acid dosing pump 34 is operatively coupled to the controller 16 by means of hard wiring 37 which extends from the controller 16 to the acid dosing pump 34. The acid dosing pump 34 pumps acid through the pipeline 36 and out through a dosing point into water from the reservoir at the direction of the controller 16. The controller acts in response to the sensed levels of acid in the water and the target level of acid in the water.

The swimming pool on which the management system is operatively installed is indicated generally by the reference numeral 40. The swimming pool 40 comprises a containment structure made of a material such as concrete which is indicated generally by reference numeral 42. The structure 42 has an open top 43 and is filled with water shown by numeral 44. The swimming pool 40 also includes a recirculating arrangement comprising a recirculating conduit indicated by numeral 46 and a recirculating pump indicated by reference numeral 48 coupled in line or in series with the recirculating conduit 46. The swimming pool 40 also includes a sensing and dosing manifold 50 which is coupled in series with the recirculating conduit 46.

The management system 10 also includes hard wiring 52 for operatively connecting the controller 16 to the recirculating pump 48 to enable the controller 16 to manage operation of the pump 48. In particular this enables the controller 16 to switch the pump 48 off when the controller 16 determines that recirculation should be stopped.

The recirculating arrangement also includes a water filter 56 coupled in line with the recirculating conduit 46 downstream of the pump 48. The purpose of the filter 56 is to remove particulate matter and other solid matter from the water passing through the recirculating conduit 46. Various types of filters can be used in the recirculating conduit including a media or sand filter, a DE filter and a cartridge filter. As the structure and function of the various types of filters would be well known to persons skilled in the art it will not be described in greater detail in the specification.

The ORP sensor 12 and the pH sensor 14 project through the sensing and dosing manifold 50 of the recirculating conduit 46 into the stream of water. The disinfectant dosing pipeline 26 also discharges into the sensing and dosing manifold 50 in the recirculation conduit 46. Similarly the acid dosing pipe line 36 also discharges into the sensing and dosing manifold 50 in the recirculation conduit 46.

As shown in the drawing the ORP and pH sensors 12, 14 are positioned upstream of the dosing points of the disinfectant and acid pipelines 26 and 36. This is so that they can effectively and accurately sense the levels of disinfectant in the broader reservoir of water. Obviously they could not do this if the sensors 12, 14 were positioned downstream of the points where the disinfectant and acid dosing pipelines 26, 36 discharge into the manifold 50. Further as is shown in the drawings the pH sensor 14 is positioned upstream of the ORP sensor 12. Further the disinfectant dosing point is positioned downstream of the acid dosing point.

In all modes of operation the controller 16 causes the recirculating pump 48 to run in use until both the disinfectant and pH levels reach certain target levels correlating to appropriate disinfectant levels within the water 44 from the pool 40. Typically this correlates to a level of free halogen disinfectant within the pool of 1-3 ppm of free halogen. Similarly the pH level corresponds to a pH level of the water within the pool of about 7.2 to 7.4.

In the system illustrated in the drawings the controller 16 has two modes of operation. The first mode of operation is a ‘power saving management mode’ and the second mode is a ‘minimum run time management mode’.

In the ‘power saving management mode’ the recirculation pump 48 runs until both the level of disinfectant and the pH level reaches its target level. As soon as the target disinfectant and pH levels are met then the recirculating pump 48 switches off regardless of the length of run time that the pump 48 has been operating for. In this management mode the pump generally runs for less time that it would run for than if the run time was configured by a user.

In the ‘minimum run time management mode’ the recirculating pump 48 runs until both the level of disinfectant and the pH level reaches its target level. Once this condition is reached, the pump 48 switches off if the minimum run time has been met. If not, the pump 48 continues to run and to recirculate water until the minimum run time has elapsed and the minimum run time requirement has been met.

The controller 16 logs the time taken by the management system 10 to reach the target levels of disinfectant and pH over a period of time, of up to a few weeks, this can be used to further refine operation of the controller 16 and the management system 10.

The system 10 also has a safety feature that causes the productive recirculation to shut off if the target levels of the control parameters are not reached within a certain length of time. This is to avoid the situation where the system never reaches its target levels of certain control parameters because the supply of disinfectant or acid or alkali for example has been exhausted. This feature comprises fault detection which causes the system to shut off after this length of time has elapsed. Typically this feature only shuts off the recirculation time after several multiples of the minimum run time has elapsed. In addition the system may also have an alarm so as to indicate to a user that the system is operating properly and that the target levels of control parameters are not being reached because of a fault in the system.

In use the controller 16 can be configured or programmed by a user to turn the recirculation pump 48 on at certain times of the day. For example the user can define two starting times during the day at which the recirculating pump 48 will turn on and start running. Thereafter the controller 16 starts the pump 48 at each of these user defined times. When this occurs a couple of minutes are allowed to elapse to allow the ORP and pH sensors 12, 14 to stabilise and then the PH and ORP sensors 12, 14 start sampling and/or sensing the water that passes over the probes 12, 14. The controller 16 receives the sensed readings relating to levels of disinfectant and acid from the sensors 12, 14 and in response thereto instructs the disinfectant and acid dosing pumps 24, 34 to dose disinfectant and acid into the water at the dosing points on the dosing manifold 50.

In another example of use of the power saving mode, the controller 16 can be configured by a user to turn on the recirculating pump 48 every hour. Thereafter the pump switches exactly one hour after it previously switched on, and then sensing and dosing of disinfectant and acid levels continues until certain levels, e.g. target levels of disinfectant and acid are reached. The recirculating pump then switches off and this cycle is then repeated every hour. Applicants believe that there may be certain advantages with this type of operation because the levels of disinfectant and acid are more closely controlled around their target levels than with other operating techniques where the levels are adjusted to their target levels one or twice a day.

In another example using the ‘minimum run time management mode’ the controller 16 can be configured by a user to turn the recirculating pump 48 on every hour and to run it for a minimum run time of five minutes. Thus the pump 48 switches on at the same time each hour and sensing and dosing of disinfectant and acid levels continues until the target levels are reached. At that point the recirculating pump 48 switches off if the minimum run time of five minutes has been completed. If not it continues running until the minimum run time has been satisfied.

In another embodiment that has not been illustrated in the drawings, the system 10 for managing the reservoir of water 40 has an ORP sensor 12 for sensing the level of disinfectant in the water and a disinfectant dosing control system 24 for dosing disinfectant into the water under the direction of the controller 16 in response to the levels of disinfectant sensed by the ORP sensor 12. This embodiment has neither an acid sensor nor an acid dosing arrangement for dosing acid into the water that is operatively coupled to the controller. Rather the acid dosing is done quite independently of the actions of the controller. Additionally the addition of acid does not have any influence or bearing on the pump run time and when the pump is switched off. This is based solely on when the target level of disinfectant is met when in power saving mode. In the minimum pump run time mode it depends additionally on whether or not the minimum pump run time has been satisfied.

FIG. 2 illustrates a system for managing a reservoir of water that is a swimming pool that is a variation on the embodiment in FIG. 1. In this description unless otherwise indicated the same reference numerals will be used to refer to the same components.

The following description will focus on the difference between this embodiment and the previous embodiment described above.

In the FIG. 2 embodiment the disinfectant dosing arrangement is in the form of a chlorinator which is indicated generally by the reference numeral 60. The chlorinator 60 is an electrolytic cell that electrolyses a store or supply of salt that is in the water to generate free chlorine within the water that then functions as the disinfectant in the same way as the chlorine that is dosed into the water in the FIG. 1 embodiment. As the structure and function of a chlorinator would be known to a person skilled in the art it will not be described in greater detail in the specification.

In the system illustrated in FIG. 2 the generation of chlorine within the water by the chlorinator 60 controlled by the controller 16 in response to the levels of disinfectant chlorine that are sensed by the ORP sensor 12. The chlorinator 60 can only be utilised to generate chlorine from dissolved salt when the recirculating pump is running because the generation of chlorine in a static environment is potentially dangerous. However the converse is not true. The controller 16 can switch the chlorinator 60 off while the pump 48 is still running so that its operation is not tied to the operation of the pump 48. The Applicants are also aware of chlorinators 60 where the level of chlorine production can be varied and this can be controlled by the controller 16. Thus in this embodiment the chlorinator 60 is substituted for the disinfectant dosing arrangement 20 of FIG. 1. The chlorinator 60 which is operatively coupled to the controller 16 by means of hard wiring 62 and which is effectively controlled by the controller 16 essentially performs the same function as the disinfectant dosing arrangement of the FIG. 1 embodiment.

In use the FIG. 2 embodiment functions in much the same way as the FIG. 1 embodiment. Further the FIG. 2 embodiment can be run in the ‘power saving’ and ‘minimum run time’ modes like the FIG. 1 embodiment.

FIG. 3 illustrates a system for managing a reservoir of water that is a swimming pool in accordance with another embodiment of the disclosure. This embodiment has a number of similarities to the FIG. 1 embodiment described above and accordingly unless otherwise indicated the same reference numerals will be used to refer to the same components.

In the FIG. 3 embodiment the management system 10 has a sensing arrangement that senses for disinfectant and pH levels as described above, and a further sensor arrangement indicated generally by numeral 70 which also senses a third parameter pertaining to the quality of the water, namely the clarity or turbidity of the water. Thus the operation of the recirculating pump and specifically the period for which the water is recirculated each time it is switched on depends on three parameters of water quality, namely disinfectant, pH and turbidity meeting certain minimum levels. The turbidity of the water within the swimming pool is a measure of the amount of solids suspended within the water which is a measure of the cloudiness of the water. Obviously the object in a swimming pool is to have as low a level of turbidity as possible.

The turbidity sensing arrangement 70 comprises a first turbidity sensor 72 that is located in line with the recirculating conduit 46 downstream of the filter 56 and upstream of the sensing and dosing manifold 50. It also includes a second turbidity sensor 74 in line with the recirculating conduit 46 that is upstream of the filter 56. The second turbidity sensor 74 senses the turbidity of the water before it enters the filter 56 and the first turbidity sensor 72 senses the turbidity in the water when it emerges from the filter 56. The first turbidity sensor 72 is the primary turbidity sensor for determining the turbidity of water within the reservoir. The second sensor 74 can be used to compare the turbidity of water pre-filter and post filter and this may be used to aid control of this aspect of the system. Each turbidity sensor 72, 74 is operatively coupled to the controller 16 by means of separate hard wiring 76 whereby to enable the controller 16 to control operation of the turbidity sensors 72, 74.

In use the controller 16 can be configured or programmed by a user to turn the recirculation pump 48 on at certain times of the day as for the first embodiment described above. The controller then turns the recirculating pump on at each of these times entered by the user. After an initial stabilisation period, the ORP and pH sensors 12, 14, and also the turbidity sensors 72, 74 start sampling and/or sensing the water that passes over the sensors 12, 14.

The controller 16 receives the sensed readings relating to levels of disinfectant, pH and turbidity from the sensors 12, 14, 72, 74. The controller 16 monitors the improving water clarity, in the form of lower levels of turbidity with increasing time that the recirculating pump 48 is on due to solids being filtered out of the water in the filter 56. The controller 16 also monitors the levels of disinfectant and pH in the water. This process continues until each of the disinfectant level, pH level and turbidity level reaches its target level.

If the controller 16 is in the ‘power saving management mode’, when the target levels are reached for all three control parameters then the recirculating pump 48 switches off straight away. If the controller in is minimum run time mode then it additionally requires the minimum run time to be met before it switches the pump 48 off.

FIG. 4 illustrates a system for managing a swimming pool of water that is a variation on the FIG. 3 embodiment described above. In the FIG. 4 embodiment the system senses three parameters namely disinfectant, pH level and turbidity of the water and runs the recirculating pump each time it is started until each of these parameters reach their target level.

In FIG. 4 the system has a disinfectant dosing arrangement that is a chlorinator 60 instead of a dosing arrangement 20 with dosing pump 24. Otherwise this embodiment functions in much the same way as the FIG. 3 embodiment described above.

FIG. 5 illustrates a system for managing a swimming pool of water in accordance with another embodiment of the disclosure. As this embodiment has some similarities with the embodiments described above the following description will focus on the differences between this embodiment and the earlier embodiments.

In this embodiment the system senses a control parameter which is the level of hydrogen peroxide disinfectant. The system has a hydrogen peroxide sensor that senses the level of hydrogen peroxide disinfectant and in response thereto doses hydrogen peroxide through a hydrogen peroxide disinfectant dosing pump arrangement. In this embodiment there is no acid or alkali sensing and acid or alkali dosing to control the pH of the water to a set point. This is not required because the efficacy of hydrogen peroxide is not as tied to the pH level of the water as chlorine containing disinfectant compounds. Otherwise this embodiment functions in much the same way as the embodiments described above with reference to FIGS. 1 to 4.

An advantage of the method and control system described above with reference to the drawings is that the recirculating pump runs only for a length of time that is required to achieve certain objectives in the terms of the water quality and chemical balance. More specifically the pump runs until the sensed turbidity of the water reaches a target level and until the pool is in chemical balance, e.g. disinfectant and pH level and once that is achieved it switches off. Accordingly it does not run for any longer than is necessary and as such it only uses the energy necessary to achieve a desired condition within the pool and not for any longer than that. In summary the method and system described above enable a pool operator to manage recirculation time or pump run time based on sensor readings to conserve energy.

It will further be appreciated that the method and control system described above with reference to the drawings, doses disinfectant and acid or alkali until target levels are reached on a regular basis, e.g. a daily basis, and then stops dosing. Thus the pool can be more effectively kept in chemical balance, or close to chemical balance, than with some prior art techniques. Further it only adds an amount of disinfectant and acid or alkali that is required to bring the pool into chemical balance and then stops dosing. It does not continue to dose these chemicals into the pool when they are no longer required.

A further advantage of the method and apparatus described above with reference to the drawings is that it will be able to be applied widely to swimming pools including private pools in domestic dwellings across the world. Individually this can be used to achieve significant energy savings for each pool owner in an era of a high cost of electricity. Further in a collective sense this can lead to a significant reduction in the overall carbon foot print to manage the swimming pools around the world.

It will of course be realised that the above has been given only by way of illustrative example of the disclosure and that all such modifications and variations thereto, as would be apparent to persons skilled in the art, are deemed to fall within the broad scope and ambit of the disclosure as is herein set forth.

Claims

1. A method of managing a reservoir of water that has a recirculating arrangement for recirculating water within the reservoir at time intervals, the method including:

starting a productive recirculation of water within the reservoir by means of the recirculating arrangement;

sensing at least one control parameter relating to the quality of water within the reservoir; and

continuing the productive recirculation of water by the recirculating arrangement at least until each sensed control parameter has been managed in such a way that the level of that control parameter in the water within the reservoir will reach a certain level.

2. A method of managing a reservoir of water according to claim 1, which includes stopping the productive recirculation of water by the recirculating arrangement when each sensed control parameter has been managed such that the control parameter will reach a certain level.

3. A method of managing a reservoir of water according to claim 1, which includes setting the productive recirculation to run for a minimum productive recirculation time, and stopping the productive recirculation only when this minimum productive recirculation run time has been met in addition to each sensed control parameter being managed so that it reaches its certain level.

4. A method of managing a reservoir of water according to claim 1, which includes stopping the recirculation of water completely when the productive recirculation is stopped, or reducing the recirculation of water to a trickle recirculation when the productive recirculation is stopped.

5. A method of managing a reservoir of water according to claim 4, wherein said certain level of each sensed control parameter, at which the productive recirculation is stopped, is a target level of the sensed control parameter.

6. A method of managing a reservoir of water according to claim 5, wherein sensing at least one control parameter relating to the quality of water includes sensing the level of disinfectant within the water, and wherein the productive recirculation is continued, at least until, the level of disinfectant has reached its target level.

7. A method of managing a reservoir of water according to claim 6, wherein sensing the level of disinfectant within the water includes sensing the level of free halogen within the water utilising an ORP probe.

8. A method of managing a reservoir of water according to claim 5, wherein sensing at least one control parameter relating to the quality of water includes sensing the level of acid or alkali within the water by measuring the pH level of the water, and wherein the method includes continuing the productive recirculation, at least until, the level of acid or alkali has reached its target level.

9. A method of managing a reservoir of water according to claim 5, wherein sensing at least one control parameter relating to the quality of water includes sensing the level of clarity or turbidity of the water, and wherein the method includes continuing the productive recirculation, at least until, the level of clarity or turbidity has reached a certain level.

10. A method of managing a reservoir of water according to claim 5, wherein the method includes sensing two or more different control parameters relating to the quality of water within the reservoir, and continuing the productive recirculation, at least until, each of the two or more sensed control parameters has reached a certain level.

11. A method of managing a reservoir of water according to claim 10, wherein the method includes sensing one control parameter that is the level of disinfectant and another control parameter that is the pH level or level of acid or alkali in the water, and continuing the productive recirculation, at least until, the level of disinfectant and the level of acid or alkali has reached their target levels.

12. A method of managing a reservoir of water according to claim 11, further including sensing the level of turbidity in the water and continuing the productive recirculation at least until the level of turbidity has also reached its certain level.

13. A method of managing a reservoir of water according to claim 11, wherein in addition to sensing the level of a disinfectant within the water, the method also includes: adding disinfectant to the water in response to the sensed level to promote adjustment of the sensed level towards the target level of disinfectant,

monitoring the level of the sensed disinfectant level; and

during the productive recirculation of water from the reservoir.

14. A method of managing a reservoir of water according to claim 13, wherein the disinfectant is added to the water by a disinfectant dosing arrangement that includes an electrolytic cell for electrolysing a halogen containing salt to generate free halogen in the water or a dosing pump for dosing a halogen containing substance into the body of water.

15. A method of managing a reservoir of water according to claim 13, further including ceasing the dosing of disinfectant into the water, during the productive recirculation, if the water has been managed such that the target level of disinfectant will be reached within water in the reservoir, before the productive recirculation is stopped.

16. A method of managing a reservoir of water according to claim 13, further including:

monitoring the sensed pH level; and

adding acid or alkali to the water in response to the sensed pH level to promote adjustment of the sensed pH level towards the target pH level,

during the productive recirculation of water from the reservoir.

17. A method of managing a reservoir of water according to claim 16, wherein the acid or alkali is added to the water by an acid or alkali dosing arrangement that includes a dosing pump, and a dosing line for dosing acid or alkali into the water.

18. A method of managing a reservoir of water according to claim 17, further including ceasing the dosing of acid or alkali into the water, during the productive recirculation thereof before the productive recirculation is stopped, if the water has been managed such that the target level of acid or alkali will be attained before the productive recirculation is ceased.

19. A method of managing a reservoir of water according to claim 4, wherein starting the productive recirculation of water by the recirculating arrangement includes switching on the recirculating pump, and stopping the productive recirculation of water by the recirculating arrangement includes either switching the pump off or substantially reducing the volumetric throughput of water through the pump.

20. A method of managing a reservoir of water according to claim 19, wherein switching the recirculating pump on to start productive recirculation of water within the reservoir is initiated at one or more times in a given time period, and wherein the given time period could be a day or a week or a month.

21. A method of managing a reservoir of water according to claim 19, wherein switching the recirculating arrangement on to start productive recirculation of water within the reservoir is initiated once a certain period of time has elapsed since the recirculating arrangement was previously switched on.

22. A method of managing a reservoir of water that has a recirculating arrangement for recirculating water within the reservoir at frequent time intervals, the method including:

starting a productive recirculation of water within the reservoir by means of the recirculating arrangement;

sensing one control parameter that is the level of disinfectant and sensing another control parameter that is the pH of the water, and continuing the productive circulation at least until the level of disinfectant has reached its target level and the pH level has reached its target level, and then stopping the productive recirculation by switching off the recirculation of water from the reservoir.

23. A method of managing a reservoir of water that has a recirculating arrangement for recirculating water within the reservoir at time intervals, the method including:

starting a productive recirculation of water within the reservoir by means of the recirculating arrangement,

sensing at least one control parameter relating to the quality of water within the reservoir;

setting the productive recirculation of water to run for a minimum productive recirculation run time; and

stopping the productive recirculation of water by the recirculating arrangement when the minimum productive recirculation run time has elapsed, and when the sensed control parameter has been managed in such a way that the level of that control parameter in the water within the reservoir will reach a certain level.

24. A method of managing a reservoir of water that has a recirculating arrangement according to claim 23, wherein the method includes sensing two or more different control parameters relating to the quality of water within the reservoir, and stopping the productive recirculation of the water when each of the two or more sensed control parameters has reached their target level, and when the minimum productive recirculation run time has elapsed.

25. A method of managing a reservoir of water that has a recirculating arrangement according to claim 24, wherein the method includes sensing one control parameter that is the level of disinfectant and sensing another control parameter that is the pH level or level of acid/alkali in the water, and stopping the productive recirculation of the water when each of these control parameters has reached their target level and when the minimum productive recirculation run time has elapsed.

26. A method of managing a reservoir of water that has a recirculating arrangement for recirculating water within the reservoir at frequent time intervals, the method including:

starting the recirculating arrangement to recirculate water within the reservoir, sensing at least one control parameter relating to the quality of water within the reservoir; and

stopping the recirculation of water by the recirculating arrangement when each sensed control parameter has reached a certain level.

27. A system for managing a reservoir of water having a recirculating arrangement for productively recirculating water within the reservoir at spaced time intervals, the system including:

a sensing arrangement for sensing at least one control parameter relating to the quality of water within the reservoir and comparing it with a certain level for each sensed control parameter; and

a controller for starting productive recirculation with the recirculating arrangement to recirculate water from the reservoir of water through the recirculation arrangement and continuing with the productive recirculation until each sensed control parameter has been managed in such a way that will reach a certain level in the water in the reservoir.

28. A system for managing a reservoir of water having a recirculating arrangement according to claim 27, wherein the sensing arrangement includes a disinfectant sensor for sensing the level of disinfectant in the water that is operatively coupled to the controller.

29. A system for managing a reservoir of water having a recirculating arrangement according to claim 28, further including a disinfectant dosing arrangement for dosing disinfectant into water being recirculated by the recirculating arrangement, the disinfectant dosing arrangement being operatively coupled to the controller such that the controller can control the dosing of disinfectant by the dosing arrangement.

30. A system for managing a reservoir of water having a recirculating arrangement according to claim 27, wherein the disinfectant dosing arrangement includes a disinfectant dosing pump operatively connected to a tank of disinfectant, or a chlorinator that is mounted on the recirculating arrangement that is coupled to a source of electrical energy for electrolysing salt within the water to form a disinfectant that is free chlorine.

31. A system for managing a reservoir of water having a recirculating arrangement according to claim 30, wherein the sensing arrangement includes a pH sensor for sensing the level of pH in the water that is operatively coupled to the controller.

32. A system for managing a reservoir of water having a recirculating arrangement according to claim 31, further including an acid or alkali dosing arrangement for dosing acid or alkali into water being recirculated by the recirculating arrangement, the acid or alkali dosing arrangement being operatively coupled to the controller such that the controller can control the dosing of acid or alkali by the dosing arrangement.

33. A system for managing a reservoir of water having a recirculating arrangement according to claim 32, wherein the acid or alkali dosing arrangement includes an acid or alkali dosing pump operatively connected to a tank of acid or alkali.

34. A system for managing a reservoir of water having a recirculating arrangement according to claim 27, wherein the sensing arrangement includes at least one turbidity sensor for sensing the level of turbidity in the water, and wherein the turbidity sensor is operatively coupled to the controller.

35. A reservoir of water including:

a containment structure containing water;

a recirculating arrangement for periodically recirculating the water in the containment structure; and

a system for managing the reservoir of water as defined in claim 27.

36. A water reservoir according to claim 35, wherein the recirculating arrangement includes a recirculating conduit, a recirculating pump coupled in line with the recirculating conduit, and a water filter coupled to the recirculating conduit either upstream or downstream of the recirculating pump.