FIELD OF THE INVENTION

This invention has to do with circulating water supply systems, particularly but not exclusively hot water systems, and especially but not exclusively for use in multi-occupancy or commercial buildings such as hospitals, schools, colleges, offices, hotels, multi-occupancy residential homes and the like. We also make proposals for novel flow circuit components for such systems.

BACKGROUND

The present proposals relate generally to circulating water systems, preferably circulating hot water systems, with a water flow circuit defined by pipework leading out from and back to a pump to drive circulation of the water. For a hot water system there is also a heater. A cold water system may have no heater, or a cooling or chilling device for circulating water. Such systems comprise multiple user points on the flow circuit and at least some of these are outlet user points where an outlet can be opened to take water out of the system e.g. at a tap (faucet) or the like. Or, in another aspect, some or all user points might not be outlets but can be points or use stations where water is used without release from the system, such as for heating or cooling.

Previous application WO2017/134151 with the same inventorship, to which reference should be made and the entire disclosure of which is incorporated herein by reference, described improvements in systems of the kind described to enable more effective measures to be taken to assure a supply of water, especially hot water, at adequate levels in an installation of the kind described, while maintaining sanitary conditions and in particular embodiments inhibiting or avoiding the formation of bacterial colonies. It also proposed a novel valve for isolating parts of the flow system when concentric outflow and return pipes were used. A set of controlled flow regimes for the system was described.

The previous proposals included a cold water mains feed into the flow system, upstream of a heater and downstream of a pump. A similar arrangement is appropriate for the present proposals. THE INVENTION

A first aspect of our proposals relates to the control or regulation of the water supply in a circulating-type water supply system using a combined pipe structure, in which an outflow conduit and a return conduit of the flow circuit have a common wall, and in which preferably the flow circuit is branched i.e. has plural secondary circuits - e.g. on different storeys or in different regions of a building - whose supplies may need to be independently adjusted or inter- dependently balanced.

The proposal here is a water supply system of circulating type, comprising a flow circuit for water to flow around the system and a pump connected in the flow circuit to drive the flow of water, the flow circuit comprising a primary circuit incorporating the pump, and two or more secondary circuits, the respective secondary circuits being connected to the primary circuit, especially individually connected to the primary circuit as branches from it, and wherein each secondary circuit has one or more user points, these preferably and typically including one or more user outlets operable to take water from the system, and has a combined pipe structure in which an outflow conduit and a return conduit of the secondary circuit have a common wall.

According to our first proposal one or more or each of the secondary circuits comprises a commissioning regulator, which may be connected between the primary circuit and said one or more user points of the secondary circuit. The commissioning regulator comprises an occlusion mechanism to occlude flow in the return conduit of the combined pipe structure, and an actuator operable to adjust the degree to which the occlusion mechanism occludes that return conduit, and operable to set or lock the occlusion mechanism at a selected degree of occlusion.

Preferably in the combined pipe structure the outflow conduit surrounds the return flow conduit. Both outflow and return conduits may be cylindrical. Desirably they are concentrically arranged. The wall of the return conduit may constitute an inner wall of the outflow conduit (and be the common wall), while the outflow conduit has an outer wall which constitutes the outer wall of the combined pipe structure. Commissioning Regulator

The commissioning regulator is preferably a discrete device having a body defining conduit segments and adapted to be connected between separate lengths of a run of the combined pipe. Desirably the occlusion mechanism comprises an occlusion member positioned in the return conduit and which is movable, preferably rotatable, so as to present a progressively variable degree of flow resistance in the return conduit, typically by adjusting the available cross-section area for flow at a restriction or orifice point.

The occlusion member may be a body presenting a maximum occlusion area when at one angle to the flow direction, and a minimum when at another e.g. generally orthogonal angle.

There may typically be a rotation of between 120° and 70°, typically about a right angle, between these positions (as in a "quarter-turn" valve). It may be a generally flat body in the nature of a vane; thus, the occlusion member may resemble the vane of a butterfly valve. Alternatively it may be a solid body (plug or ball) with a through-bore or other arrangement of one or more through-openings to allow flow through the opening when the opening is brought into line with the run of the return conduit, but blocks or occludes flow when turned sideways on, e.g. turned through a quarter-turn relative to the direction of the return conduit.

In one preferred mode herein, the occlusion mechanism does not operate to occlude the outflow conduit, or does not operate to vary or substantially vary the occlusion of the outflow conduit. Thus there may be no occlusion member in the outflow conduit. However in this case a portion of the actuator, such as a portion of a stem carrying an occlusion member, may pass through or cross the outflow conduit especially in a situation where (as is preferred) the outflow conduit encloses the return conduit.

The conduits are preferably cylindrical. Preferably the occlusion member is rotatable around a pivot axis which crosses the axis of the return conduit, i.e. a central or median axis. The occlusion member may thus be generally circular in form, that is, a disc. However other forms may be used, especially since full closure may not be needed as discussed below. A further distinct feature here may arise because the function of the commissioning regulator is desirably or in most cases only to adjust the supply pressure relatively, to balance the supplies. For this purpose it is not necessary that the occlusion member of the regulator can totally block the return conduit, or seal it off. It is then preferable that in its position of maximum occlusion, the occlusion mechanism does not completely block the return conduit. For example at least 1%, or from 1-20% or from 1-10%, of the maximum available flow area of the return conduit at the location of the occlusion mechanism or occlusion member may remain open for flow in this position. This is desirable firstly because full sealing or closure at the occlusion mechanism might needlessly add an undesirable trap volume or dead space to the system. Also, the provision of full sealing as in a valve increases cost and complexity, and such sealed devices sometimes also require extra certification or homologation for use. When, as is preferred, the function of the present commissioning regulator is the function of adjusting and balancing supply as between secondary circuits, a function of providing full isolation of a secondary circuit, e.g. full isolation from the primary circuit in order for maintenance work or the like, if needed, can be given to a separate isolation valve.

Preferably the commissioning regulator comprises a body adapted to be coupled to adjacent lengths of combined pipe, and defining a segment of conduit with first and second unions for connection to the ends of the respective combined pipe lengths, and an internal wall dividing the conduit segment defined by the regulator body into outflow and return flow conduit sub-regions or sectors, corresponding to the outflow and return flow conduits of the combined pipe connected to it.

As explained the combined pipe is preferably formed from nested or concentric tubes or pipes, so that the internal wall of the commissioning regulator may be an inner tube segment mounted, by means of appropriate radially-extending support structures, in nested or concentric relation with an outer tube segment. The outer tube may be defined by the regulator body itself, or by a tubular insert therein. The actuator mechanism can be mounted on or in the regulator body, and desirably includes an actuator stem which projects into the conduit region. It may extend across the outflow conduit region (e.g. in the diametrical position) and through the intermediate wall (such as through the wall of an inner tube segment) and into the return conduit segment of the regulator where it carries the occlusion element such as a rotatable vane. Again, close sealing around the actuator stem where it penetrates the return conduit wall is not necessary, since the return and outflow conduits are part of the same system and only the outer (preferably outflow) conduit need be fully sealed relative to the environment. For the latter purpose, where a rotational actuator stem passes through the regulator body, sealing such as by packing or one or more sealing rings may be provided.

The actuator mechanism preferably provides for essentially continuous adjustment over a range of available movement of the occlusion member, combined with means to set or lock that position once established. This may be done e.g. by means of a threaded locking screw or locking sleeve engaging the body and surrounding the rotatable stem coaxially, which can be tightened to clamp it in position relative to the regulator body when the desired adjustment is reached. A skilled person can conceive other suitable adjustment and locking mechanisms in accordance with the type of actuator mechanism.

The regulator body may have receiving structures for holding the ends of the external combined pipe lengths in sealed relation with the conduit segment defined by the regulator body. Typically these structures comprise union openings of the body into or onto which the ends of the combined pipe can be pushed or fitted, bringing the outflow and return conduits of the external pipe into register and communication with outflow and return conduits defined by the regulator conduit segment. The end of the intermediate wall/inner tube segment of the regulator may be in axial register with a stop formation for the outer pipe wall, so that a simple combined pipe end form (with the walls of the return and outflow conduits terminating at the same axial length, e.g. after cutting) can be fitted on and immediately establish adequate communication for both conduits. A full seal between the outflow and return conduits is usually not needed, because they are part of the same water system.

The joint of the outer pipe of the combined pipe to the regulator body may be e.g. by means of screw-on clamp rings acting on compressible seals, or crimpable portions, or other known means, optionally with inserted seals such as O-rings. The outer pipe wall may be formed into (or be pre-formed with) an outward flange to be engaged by such clamp rings. The union openings of the body may have engagement formations such as screw threads to engage such clamp rings. The skilled person familiar with the installation of water piping systems is aware of a range of options in this respect.

Preferably as shown herein the combined pipe connects to the regulator body as respective lengths of pipe on either side with the regulator body between, such as pipe lengths in line or coaxial. The union connection structures of the regulator body are positioned accordingly. However any arrangement of combined pipe allowing the regulator to exert its function may be used. For example the pipe lengths may be angled to one another at the regulator. Or, a regulator having any of the features proposed herein as regards the occlusion member and its operation may be positioned at the end of a pipe run forming a circuit or secondary circuit, at the pipe terminus where the outflow conduit is connected to the return conduit.

Isolation Valves

In a system of the kind described, it is desirable to be able to isolate the secondary circuits from one another and/or from the primary circuit. Preferably, in the present proposals, one or more or all of the secondary circuits has a respective isolation valve for fully closing off both the outflow and return conduits of the secondary circuit.

Desirably this function is provided by a single isolation valve device acting on both the outflow and return conduits of a combined pipe structure in the secondary circuit. For this purpose we prefer the use of an isolation valve having a single movable closure element acting in relation to both the outflow and return conduits together. Thus, it may comprise a movable closure element defining conduit segments (through the closure element) which correspond in form and orientation to the return and outflow conduits of the combined pipe structures leading to and from the isolation valve. The closure element may have an inner tube segment mounted coaxially inside an outer conduit segment so as to define inner and outer conduits (respectively return and outflow, preferably) . The inner tube segment may be supported inside the outer by a radial support structure such as plural circumferentially-spaced struts, fins or axially-extending walls. Desirably the movable closure element is a rotatable closure element movable by rotation between open and closed positions, e.g. through a quarter-turn, relative to a housing or body of the isolation valve. It may be operated e.g. by an actuator accessible or operable from outside the valve, such as by hand, or by an actuation tool e.g. screwdriver, spanner, wrench or the like engaging the actuator.

The isolation valve may be a ball valve, in which a said rotatable closure element has a spherical exterior surface portion of the outer conduit part to effect sealing of the outer conduit. Or, it may be a modified ball valve in the form of a plug valve i.e. the movable element having a cylindrical or conical outer surface slidable in sealing relationship with a correspondingly-shaped cylindrical or conical seat of the housing or body. The skilled person will appreciate that other forms such as oblong-section, lozenge- section or oval-section closure elements may be used.

As disclosed in our earlier application, the fixed structure of the isolation valve includes first and second sealing portions or arrangements to seal against and around the respective oppositely-directed ends of the movable element (the ends facing towards the connected lengths of combined pipe).

Preferably the isolation valve is a discrete unit adapted to be coupled into adjacent lengths of combined pipe. For connecting an inner conduit, it may have inner connector or union portions to slide into, around or onto the inner pipes of the combined pipe, and outer tubular unions to slide into or around the outer pipes of the combined pipe.

These coupling structures may be comprised in or contained within a valve body or housing which also mounts an external operating member of the actuator, and by which the movable element can be moved or turned between its open and closed positions. In the closed position the surface of the movable closure element, e.g. cylindrical or spherical surface, closes off at least the outer flow conduit with a sealing engagement on at least one side of the valve and preferably at both sides of the valve, that is to say, preferably in relation to both the attached lengths of combined pipe. A seal on only one side could provide the necessary isolation, however.

In the open position, the outflow and return conduits are open through the isolation valve for flow. As mentioned above, in the open position it is not critical that a true seal be formed for the jointed connections between the inner tube of the valve's movable element and the inner tube or tubular union of the adjacent fixed part or of the run of combined pipe connected to the valve.

Moreover, as disclosed in our earlier application, a particular preferred option is for the closure member to have a relatively recessed region on its outward surface, bounded by the seal which is formed in the closed position, whereby the surface of the closure member is recessed away from the end of the inner or return pipe of the combined pipe, or from a corresponding union tube comprised in the valve. In the closed position both conduits are then fully sealed from the other side of the valve and relative to the exterior, but the inner and outer conduits on at least one side of the valve are in communication for appreciable flow via the recess because the end of the inner tube is spaced from the valve closure element. This allows circulating flow to continue on that side of the closed valve - especially, the primary circuit side - avoiding a potential dead space and helping to maintain sanitary conditions. As for other features, desirably the isolation valve closure member has this communication recess feature on both sides so that the valve can be installed either way round.

Desirably each of plural secondary circuits has such an isolation valve positioned between a point of branching from the primary circuit and a first user point, especially a first outlet user point, of the secondary circuit (in the direction away from the primary circuit). It is also preferred that isolation valves (e.g. in accordance with the above proposal) and commissioning regulators (e.g. in accordance with the above proposal) are both used such as in accordance with the first aspect above, and that the isolation valves and commissioning regulators are separate devices. It is preferred that the isolation valve be located between the commissioning regulator and the primary circuit.

An embodiment in which the functions of the commissioning regulator and isolation valve are combined into a single device is also possible, as indicated later, although the relative complexity of such a device may be less preferable.

Circuit Features

Preferably in a circuit with said secondary circuits, i.e. a branched circuit, the different secondary circuits, or at least some of them, correspond to different height levels of the system such as different storeys of a building in which the water system is installed. Such a circuit might have only one branch, in which case the distinction between primary and secondary for the parts branched relative to one another may of course be arbitrary i.e. they may both be secondary and the single run up to the branch is primary, or one may be regarded as part of the primary and the other is the sole secondary.

In either case there may be a role for one or more commissioning regulators as described.

A primary circuit to which secondary circuits are connected may also comprise or be substantially formed of combined pipe of any kind as mentioned above, and preferably the same type and dimensions as used for the secondary circuits. The primary circuit may be in the nature of a manifold extending between branch points of the respective secondary systems, such as up and down a building in which the secondary systems are on different storeys. At or adjacent the position of the pump, and a heater if there is a heater, desirably the primary circuit has a simple pipe structure (as distinct from combined pipe) in which the inflow and outflow conduits are separate, without a common wall. A confluence joint, such as a T-joint, can be adapted to provide the point where the separate outflow and return conduits merge to form a combined pipe structure. Proposals for this are described below.

Desirably the system is a hot water system, in which the primary circuit includes a heater as well as the pump. The primary circuit also includes a feed point for external water supply, where a supply such as a cold water mains supply is connected into the present water system. As known, such a connection is usually via a check valve to prevent any back- flow. The heater is desirably a through-flow heater which forms part of the flow circuit, as distinct from an immersion- type heater which heats water residing in a tank. Depending on the volume of the system and the anticipated demand, there may be an advantage to having an accumulator chamber to increase the available volume of water, especially hot water in a hot water system. Such an accumulator chamber may be included in the primary circuit, downstream of the heater, and is also desirably constructed for through-flow. Preferably it has an inlet and outlet at opposite ends - preferably the inlet at the bottom and the outlet at the top - and shaped to avoid dead spaces. This is in line with the proposals set out in our earlier application, whereby a hot water system embodying the proposals is operable so as to avoid or reduce risks of microbiological contamination or proliferation.

Desirably each secondary circuit has plural outlet user points, such as taps. Preferably the outlet user points are provided, in accordance with the general teachings of our earlier application, on a sub-branch or outlet branch which itself has a combined pipe structure, with an outflow outlet branch conduit and a return flow outlet branch conduit so that there can be circulation (avoiding dead spaces) all the way to the outlet point. The proposals in our earlier application are applicable. Where the outlet user points are taps and the system is a hot water system, desirably the taps are or include mixer taps such as automatic mixer taps where a separate cold supply is present and the tap automatically combines the hot and cold supplies to produce output water at an acceptable temperature - this is well-known.

One or more or all of the user point sub-branches may themselves include respective isolation valves, e.g. in line with the proposals above, to enhance the flexibility of the system for local shut-off.

Outlets and user points of other kinds may be present according to the application of the system. Moreover the skilled person will understand that the system is not necessarily a hot water system but may be for water at ambient temperature, or indeed for chilled water, since this also takes advantage of the effect of the outer conduit to shield the inner conduit from environmental temperatures.

Optional Shut-Off

Our previous application proposed a system in which the system initiated (automatically) a shut-off of the return conduit in the event of substantial water usage at one or more outlets, to maximise the pump capacity available for driving flow at the outlets. We find that such a facility is not always necessary, but it may be provided in the present system either in the main return (e.g. in the primary circuit) or in any of the secondary circuits (e.g. in a main return of the secondary circuit).

Other Aspects

A circulating water system having plural secondary circuits of the type described above, and having isolation valves and commissioning regulators on each of the secondary circuits, is itself a proposal for a combined pipe system and is therefore an aspect of the present proposals, including embodiments where the commissioning regulator and/or the isolation valve used are of a type other than specified above.

The commissioning regulator as described is an aspect in itself, as is any combined pipe water system including one or more such regulators.

An isolation valve using a cylindrical or conical plug- type movable member, or other form of rotatable movable member such as oblong-section, lozenge-section or oval-section, and a water supply system comprising such a valve as an isolation valve, especially a circulating water supply system, are further aspects of the present proposals, as described above.

A further aspect and structural option in a water system proposed herein is a combined isolation valve and commissioning regulator, that is, combined in a single device.

It will be understood that in some respects an isolation valve can provide the function of a commissioning regulator, since usually the valve has a continuous movement from fully open to fully closed. Accordingly, it is in principle possible for both functions to be provided by incorporating means in an isolation valve for it to be locked at any selected degree of opening. While this option is not excluded by the present proposals, it may be non-optimal in that the pre-set of the regulator is lost when the isolation valve is operated. It may also be unfamiliar for the operator, or the complexity of the device may cause expense. However the present proposals include an alternative in which an isolation valve of the general kind described above, with a rotatable closure member of ball or plug form defining conduit segments as described above, additionally comprises a regulator feature by means of an occlusion member such as a rotatable vane positioned in the inner conduit (especially return conduit) of the valve, and having a separate actuator by means of which its orientation relative to the flow direction can be adjusted and locked, as described above for the commissioning regulator. Such a concept can be implemented for example in a ball-valve as described above, in which an operating spindle for the closure valve and an operating spindle for the regulator member are co-axially arranged, and preferably extending in opposite directions out of the valve housing for convenience of distinction and operation. By this means, it may indeed be possible to operate the isolation valve (turning the closure member) without disturbing the position of the occlusion member of the regulator.

CONDUIT TYPE: GENERAL

Desirably the conduits of the pipes, and especially of the combined pipe structure, are pipes made from materials resistant to bacterial growth, such as stainless steel or copper. However subject to requirements it may be possible for one or both to be made from plastics material. The pipe material may have a coat or coating layer facing onto the conduit to modify its properties, e.g. to confer resistance to microbiological growth or contamination, and particularly but not exclusively for polymeric pipes. Where - as is preferred - one pipe is positioned surrounded by a flow in the other (e.g. concentrically), continuous or intermittent radial support structures are desirably provided between the pipes, e.g. projecting outwardly from the inner pipe, inwardly from the outer pipe or as discrete elements fitted between them, to hold the inner one in position relative to the outer. This is known and the skilled person can use any available means for this.

PUMP

The pump is provided in the primary circuit, and desirably at a portion of the system having single pipe flow. In a hot water system, typically the pump is upstream of the heater. Any suitable pump may be used, in line with conventional knowledge. Preferably it is a pump with controllably variable pumping rate.

WATER SOURCE SUPPLY

When water is taken from the system at an outlet user point, the water taken must be replaced. Preferably no static water storage vessel or reservoir is provided, so that the water supply system consists essentially of the circulatory flow system and its branches. To this end, in a hot water system the heater may act directly or in-line on water flowing in a circulation conduit through the heater, rather than heating a substantially static volume in a storage or accumulator vessel.

Preferably a pressurised supply e.g. from a cold storage vessel, but more preferably from a pressurised cold water main, is connected to feed water into the circulating system to compensate for water taken at outlets.

This pressurised supply may be e.g. by a simple connection into the water circuit, desirably upstream of a heater thereof when present. The supply preferably enters downstream of the pump so that the maximum supply rate can exceed the pumping capacity, and/or to facilitate interruption of circulation if a facility is provided for this. The supply may be initiated via a check valve at the connection into the water circuit, responding to pressure drop in the circuit (especially when an outlet is opened) to supply water under mains pressure.

HOT WATER/HEATER

In a hot water circuit, by providing a suitable heater of sufficient power an adequate supply of hot water at essentially mains pressure, or at the supply pressure/rate of the cold supply, can be available at all times. The heater type is not specifically limited. The required heating power output will depend on the size of the system and on the anticipated maximum flow demand. The heat output is preferably controllable or adjustable in operation.

Examples of suitable heaters include electrically-powered or combustion fuel instant (non-storage) heaters; other types may be used. One particular suitable type is a gas-fuelled (e.g. natural gas or propane) heater using exhaust heat to pre-heat the incoming water flow. Preferably a sensor is provided to detect when cold water or water below the predetermined circulation temperature is being fed into the circulating system. This may be e.g. a flow sensor in the supply conduit, or a sensor for detecting opening of a valve or the like. Such a sensor can be connected to a control system to adjust the output of the heater in accordance with need.

COOLING DEVICE/CHILLER

As mentioned above the provision in the system of a cooling device or chiller to act on the circulating water and reduce its temperature is a further option. Such a device may be included instead of a heater, at a similar position in the system where a heater would be e.g. as shown herein. Or, both a heater and a cooler/chiller may be provided, disposed so as to operable to act on the same circulation, or on separate circuits. As with a heater, a cooler or chiller can be subject to automated or programmed control in the system and disclosures herein about the control of a heater are applicable mutatis mutandis to the control of a cooler or chiller.

SYSTEM CONTROL

The present system desirably comprises a programmed control system. Elements of the control system, and programmed regimes in which it is operable, may be as described in our earlier application and are set out again here only for completeness. The control system is not indicated in the subsequent descriptions of examples, but it is assumed to be present in line with skilled knowledge. A water system of any type disclosed above in combination with such a programmed control system is part of the present proposals.

Generally the control system comprises at least one temperature sensor for detecting the temperature of water flow. There may be a sentinel temperature sensor for detecting the circulating flow temperature at a most remote point (or most remote user point) of the system, for example where the outflow conduit communicates with a return conduit where these run side by side e.g. as proposed above.

There may be a return temperature sensor for measuring the temperature in the return conduit shortly before it enters the heater, e.g. after a pump, typically downstream of or at the end of any region where the return conduit interacts with the outflow conduit. There may be individual outlet or user point temperature sensors at one or more user points. There may be a supply temperature sensor for measuring the temperature of supply water fed to the circulating system e.g. from a main or cold vessel. Outputs from such temperature sensors are fed to a programmed control processor, via an appropriate transducer if necessary. The control processor is programmed to be able to adjust the operation of any or all of: the pump (on or off, or adjust flow rate or output power), the heater (on or off, or adjust heating rate), a flow restrictor or closure valve (open, shut, or partially open to a predetermined degree) in dependence on any one or more of the above outputs from temperature sensors.

The control system may comprise one or more flow sensors e.g. to sense the presence, absence or rate of flow in the circulating system, and/or at an outlet thereof, and/or in or from a supply for external water such as a supply main as discussed above. Again, outputs from such sensors are fed to the programmed control system which may be programmed to operate or adjust any of a heater, pump or closure valve or flow regulator in dependence on the detected outputs. In particular, as mentioned, the system may be programmed to respond to consumption of hot water from the system, detected as flow at or near an outlet user point or with reference to the external supply, by actuating a return flow shut-off or return flow restriction. The control processor may be programmed to increase the power output of the heater in dependence on detected increased flow rate in the circulating system and/or in the external supply conduit e.g. above predetermined threshold values or on a continuously variable basis.

The control processor may be operable in a stasis mode - corresponding to circulation of heated water through the hot water flow circuit and heater without consumption at the outlets - and a distinct dynamic mode when hot water is consumed at one or more open outlet user points.

In the stasis mode, the control processor is operable to maintain a predetermined flow rate - preferably corresponding to laminar flow - and a predetermined operating temperature in the circulating flow at least with reference to one or more predetermined points, e.g. at least at a final sentinel temperature sensor and/or at a return temperature sensor.

These may be set as a minimum temperature in the system, the controller being operable to modulate the heater output and/or to reduce the flow rate in the event that the detected temperature drops below the predetermined minimum. Desirably the program is operable to maintain a return temperature sensor temperature of 50°C or above.

The control processor may also be programmed to operate in an exceptional stasis mode or pasteurisation mode in which flow rate and/or heater output are adjusted to achieve an exceptional raised minimum temperature such as 60°C, 65°C or 70°C. By these means it is possible e.g. to carry out a precautionary decontamination or pasteurisation of the system from time to time to ensure that no bacterial colonies can establish. The system may be programmed to operate this mode only in special maintenance periods or periods of non-use, or subject to a warning or precautionary non-availability or hot water at the outlets. In any event the system desirably comprises thermostatic or other automatic mixing devices at the outlets, for mixing with cold water to approximate a target temperature or prevent exceeding a maximum temperature, to maintain safety.

The control processor may be programmed to switch the system from the stasis mode to the dynamic mode when outlet flow is detected, e.g. at a respective outlet or by means of detection of flow in or from an external supply system. The dynamic mode may involve stopping or slowing the pump and/or shutting off or restricting circulating flow, especially return flow before the heater, so that flow at the outlet(s) proceeds under pressure primarily or solely from the external supply. The heating rate may in this case be adjusted in dependence on a detected temperature at a predetermined point in the hot water circulation system, e.g. at the open outlet, at a sentinel outlet, and some other predetermined point on the system, and optionally also on a detected temperature or control and/or flow rate of the external supply. When outlet flow stops, as detected by any flow sensor as mentioned, the control processor may automatically revert to the stasis mode e.g. by opening a shut-off valve or flow restrictor, turning on or accelerating the pump and adjusting the heater output to maintain a target temperature corresponding to the stasis mode.

A further option is for the control processor to be operable in a dormant mode in which the pump is turned off and/or flow is shut off with no circulation, and/or in which heating is turned off or reduced to a reduced predetermined level corresponding to a dormant temperature below the predetermined operating temperature or minimum temperature mentioned above. In particular, a dormant mode with neither circulation nor heating is envisaged. The system may be programmed to initiate or allow the dormant mode after running the pasteurisation mode, when there should be no viable biological activity in the system. The dormant mode may be programmed to run for a predetermined period, or during a certain time of day, and/or until there is use of water at a user point, triggering return to the dynamic or stasis mode. Availability of an appropriately programmed dormant mode can save energy without compromising safety. This is not a feature of existing systems which, even if they could be run at pasteurisation temperatures, lack full circulation (i.e. they have dead legs) so that actual pasteurisation is not achievable and correspondingly a dormant mode cannot safely be used.

If water is - perhaps unexpectedly - taken from the system while in dormant mode, the controller may be programmed to provide a dormancy interruption mode - a form of transition to a dynamic mode - in which on detection of the outlet flow the pump remains stopped and circulating flow remains shut off by the valve, but the heater is turned on to heat incoming cold water directly to 60°C or more.

To summarise: the system may comprise a control system including a programmed control processor, operable according to any one or more of the following modes:

- to adjust the operation of any or all of the pump, a heater and a flow restrictor or closure valve in dependence on the output from one or more temperature sensors comprised in the system;

- to respond to consumption of hot water from the system, detected as flow at or near an outlet user point or with reference to the external supply, by actuating a shut-off valve or flow restrictor for the return conduit; - to increase the power output of a heater of the system in dependence on a detected increased flow rate in the flow circuit and/or in an external supply conduit e.g. above predetermined threshold values or on a continuously variable basis;

- to switch between a stasis mode, corresponding to circulation of heated water through the flow circuit without consumption at the outlets, and a dynamic mode when hot water is consumed at one or more outlets, the stasis mode operating to maintain a predetermined flow rate and a predetermined operating temperature in the flow circuit, and the dynamic mode operating to stop or slow the pump and/or shut off or restrict circulating flow and/or increase heater output;

- to operate in an exceptional pasteurisation mode in which flow rate and/or heater output are adjusted to achieve an exceptional raised minimum temperature of at least 60°C,

65°C or 70°C to decontaminate the system;

- to operate in a dormant mode in which the pump is turned off and/or flow is shut off with no circulation, and/or in which heating is turned off or reduced to a reduced predetermined level corresponding to a dormant temperature below a predetermined operating temperature, and preferably with neither circulation nor heating.

DESCRIPTION OF THE DRAWING FIGURES

Examples and possible modes of implementation of the invention are now illustrated with reference to the accompanying drawings, in which:

Fig. 1 is a schematic view showing the layout of the components in a circulating water system or relevant general type using combined pipe;

Fig. 2 is a schematic view showing the disposition of commissioning regulators and isolation valves in a circulating system of the general type shown in Fig. 1;

Fig. 3 is a longitudinal vertical cross-section through a commissioning regulator connected into a run of combined pipe;

Fig. 4 is an end view of the commissioning regulator;

Fig. 5 is a top view of the control block of the commissioning regulator;

Figs. 6 and 7 are vertical axial cross-sectional views of an isolation valve in a first embodiment, in opened closed positions respectively; Fig. 8(a) is an end view of an inner conduit union of the Fig. 6/7 isolation valve, separated from the valve, while Fig. 8(b) shows both the inner conduit unions from the side;

Fig. 9 is an end view of the movable member (ball member) of the Fig. 6 and Fig. 7 isolation valve by itself, as seen along the pipe in the open position;

Figs. 10 to 13 show a second embodiment of isolation valve using a cylindrical (plug) closure member, Fig. 10 being a schematic side view indicating internal detail, Fig. 11 being a similar top view, Fig. 12 being an end view indicating features of the movable plug in an open position, and Fig.

13 (a) and (b) being respectively a side view and an end view of an inner conduit union of the valve;

Figs. 14 to 16 show a third embodiment of isolation valve with a different arrangement of a cylindrical movable plug member, Fig. 14 being a side view with internal detail indicated schematically in an open position, Fig. 15 being a similar view in a closed position and Fig. 16 being an end view;

Fig. 17 and 18 show a fourth embodiment of isolation valve, similar to the first embodiment but using separate seal rings instead of providing the seals integrally with the tube unions;

Fig. 19 is a vertical cross-section of the movable member (ball member) of an isolation valve, showing how a commissioning regulator function can be incorporated into the same device;

Fig. 20 shows enlarged forms of connector or junction structures whose positions are also indicated in the schematic drawing of Fig. 2, Fig. 20(a) showing a confluence T-joint where single pipes join or emerge from a combined pipe and Fig. 20(b) showing a T-joint for combined pipe, where one combined pipe meets another, and

Fig. 21(a)-(d) show an outlet connector for a user outlet point, where a combined pipe branch connects to a tap or the like (not shown). Fig. 21(a) and (b) are schematic axial cross-sections showing flow conditions with the outlet open and closed respectively, (c) and (d) are end-views (radial cross-sections) from the supply direction and from the outlet direction.

DETAILED DESCRIPTION Referring firstly to Figs. 1 and 2, a hot water circulation system 1 is arranged to supply four different levels or storeys of a building. At a main operating station it comprises a valved intake 13 from a cold water main, feeding into a through-flow direct heater 2 and thence into the outflow of the system. The pipe systems constituting the system fall generally into a primary circuit 11 - indicated schematically by a broken-line surround line in Fig. 1 - and individual secondary circuits 21-24 for the respective storeys as indicated, each secondary circuit representing a branch from the primary circuit, and being independent or separable from the other secondary circuits.

As seen particularly in Fig. 1, the system consists essentially of combined pipe 14, that is, a pipe structure in which an inner pipe 18 and an outer pipe 17 are arranged concentrically, the inner pipe forming an inner conduit 15 which in this system acts as a return flow, while the space between the inner and outer pipes defines an outer conduit 16 which in this system is the outflow. The primary circuit connects to the secondary circuits at T-joints 6 which are made in the combined pipe, with the outer conduit of the primary circuit connecting to the outer conduit of the respective secondary circuit and similarly for the inner conduit .

The operating station has a region of single-pipe structure 12: a single-pipe outflow conduit 12 runs from the cold water supply 13 through the heater 2 and to a confluence joint 9 where it merges with the outer conduit 16 of the combined pipe system 14. At that confluence joint the inner pipe 18 separates from the combined pipe system 14 to be a single-pipe return conduit 12' which passes through the system pump 3 and back to the heater inlet.

The return conduit 12' joins the supply line from the supply main 13, which (in known manner) meets the circuit at a check valve 31 so that the circulating system is replenished as needed under mains pressure while back-flow is prevented.

Each secondary circuit 21-24 has a series of user outlet points 5 which in this embodiment are mixer taps or hot taps. At each outlet user point 5 a sub-branch from the secondary circuit branch is formed at a T-joint for combined pipe, which may be similar to that used where the secondary circuits branch from the primary circuit, so that circulating flow prevails right around the system without the formation of dead spaces. For mixer taps, a cold flow (not shown) is combined at the tap in a manner known per se. On each secondary circuit the final outlet point 5 represents a terminus or sentinel point for that secondary circuit branch, where the secondary circuit outflow enters the inner conduit and flows back towards the operating centre and ultimately the pump 3.

In Fig. 1, reference numeral 4 generally designates a functional position for one or more flow-control devices to control communication between the primary and secondary circuits. One function is isolation, by means of which both inner and outer conduits can be fully shut off from the primary circuit e.g. for shut-down or maintenance of the secondary circuit. Another function is supply pressure regulation or balancing, by means of which compensation is made for the effects of differences of height and/or supply path length for the different secondary circuits, so that each secondary circuit sees a suitable matched supply pressure for its user points. In a multi-storey building, a skilled person is familiar with balancing secondary circuits so that flow at the lowest level is the most restricted by regulation and the highest level the least, since the highest level suffers the greatest supply pressure loss due to height. Regulation for balance is preferably applied on the return arm of a secondary circuit.

Our previous application made some proposals for isolation valves which can operate with combined pipe. Here we include proposals for commissioning regulators suitable for pressure balancing with double pipe.

Fig. 2 shows one preferred disposition of these facilities, in which each secondary circuit has a respective commissioning regulator 7 and isolation valve 8, positioned with the isolation valve 8 between the commissioning regulator 7 and the primary circuit 11, and the commissioning and isolating functions being performed by separate devices.

They may in some embodiments be performed by the same device, as mentioned below, but separate provision is preferable because simplicity of the devices significantly reduces cost and maintenance.

An embodiment of the commissioning regulator as shown in Figs. 3-5 is designed to be connected into a run of combined pipe 14, and comprises a main body 71 preferably of brass, of generally tubular conformation with oppositely-directed end unions 72 with external threads and forming internal sockets 721, each having a stop shoulder 722 to define and limit the distance of insertion of an outer pipe of the combined pipe.

In the embodiment shown, retention and sealing of the pipe ends is by means of internally-threaded clamping rings 74 with an inward flange which traps an outward flange 141 on the outside of the pipe end, holding the pipe in position and in sealing relation at the outside.

The regulator also comprises an inner tube segment 73 mounted concentrically in the main bore of the body 71, so as to match the form and position of the inner pipe 18 of the combined pipe 40. Concentric mounting of the inner pipe segment 73 may be e.g. by means of radially-extending (e.g. diametrically-opposed) struts, fins or the like. In the assembled condition, the end openings of the pipe segment 73 meet closely adjacent the exposed inner pipe edges of the inner pipe 18 of the combined pipe, albeit without an actual seal, so that effectively the outer and inner flow conduits (outflow and return) of the combined pipe continue through the regulator device 7.

The functional element of the device is an occlusion mechanism generally designated 75, for variably occluding the interior of the inner conduit. Specifically the occlusion is provided in the inner pipe segment 73 of the device, by means of a plate or vane 756 carried on the end of a spindle 755 which projects through a small hole in the wall of the inner pipe segment 73, traverses the outer conduit 16 and joins integrally a main shaft 751 which is mounted rotatably through a hole in the wall of the body 71, with a sealing ring 757 to prevent leakage. The top of the main shaft 751 has a slotted control head 752, and it is surrounded at its top end by a locking sleeve 753, with an external thread engaging in a bore around the top part of the shaft 751, and having a top tool- engagement form (here, a nut) so that it can be tightened down to fix the shaft 751 at any angular orientation after the angle has been adjusted using the slotted control head 752.

A quarter turn adjustment moves the vane 756 between the fully-open position shown in the Figures, in which the vane is presented side-on to flow in the inner conduit 15 and presents minimum resistance, to a maximum occlusion condition in which the vane faces the flow and occludes most of the inner conduit 15. In the closed condition the outline shape of the vane - shown in this embodiment as a circular disc - substantially complements that of the conduit interior, but there is no need for a positive seal against the conduit wall because this device cannot in any case isolate the secondary circuit (the outer conduit being open at the device) and isolation is provided by the isolation valve. Regulation (supply pressure balancing) can be effectively done with a vane which can only partially occlude the conduit, provided that it can be continuously adjusted and reliably locked at a selected position of adjustment. Adjustment or balancing of supply pressure among secondary circuits, by selected degree of occlusion of a return conduit on the secondary circuit, is understood by a skilled person.

The commissioning regulator can therefore be a relatively simple and inexpensive device to manufacture.

Figs. 6 to 9 show details of an isolation valve 8 used for temporarily separating or isolating different sections of the flow conduits from one another, e.g. for maintenance or repair.

The isolation valve 8 is a quarter-turn valve consisting essentially of a body or housing 870 and a rotatable closure member 860. The body 870 consists of a main body portion 871 and a retainer body portion 872. Each body portion 871,872 comprises a tubular outer union 873 sized to receive slidingly an end of a respective outer pipe 17, with an external thread for the sealed securing of the outer pipe. The main body portion 871 defines an interior cavity for the ball 861 of the closure member 860, and the bonnet 874 of the valve which includes a packing seal 875 and retaining nut 876 for the actuating spindle 862 of the closure member 860. Actuation may be manual, or automated e.g. by any conventional drive. A conventional turn handle 869 is shown. The body retainer portion 872 screws into the main body portion 871 to enclose the valve mechanism and hold the components in place. An opposed pair of seat union components 880 are retained in this cavity, held between the body portions by external flanges 885, and these provide both peripheral seals (seats) 881 for sealing around the ball 861 and central inner union tubes 882 for sliding connection with the inner (return) pipes of the circulation system. The seat union components 880 have outer tubular extensions 884 fitting into the outer union tubes 873 of the body portions whose internal diameter matches that of the outer pipes, and the end surfaces of these extensions provide stop abutments for the outer pipes. The inner union tubes 882 are mounted concentrically in the seat union components 880 by support members 886 in the form of short walls or fins extending axially to minimise flow obstruction. Two opposed fins are shown; other numbers and shapes may be used.

Fig. 9 shows that the ball member 861 consists of a main outer tube 864 having a spherical outer surface 865 and a cylindrical inner surface 869 facing onto an inner tube 866 which is supported concentrically with the outer tube 864 by means of support walls 867 which, in the open condition of the valve, may extend as continuations of the support walls of the fixed seat unions 880. The internal diameters of the inner and outer tubes 864,866 generally match those of the inner and outer pipes 18,17 of the main conduit, so that the valve is effectively of a full port type with minimal reduction of flow cross-section through the valve in the open condition. In the closed condition, with the actuating spindle 862 turned a quarter turn, the external ball surface 865 turns around to close off entirely the pipes at both sides of the valve 8, with sealing around the seats 881 of the seat union. Seals at these points may be provided by resilient or deformable seal members, such as PTFE rings (not shown). No discrete seal member is provided for sealing between the inner union tube 882 of the seat union and the inner tube 866 of the ball 861 in the open position. Close proximity suffices for ordinary operation because the same system water is present in both conduits and a modicum of leakage is not harmful provided that adequate pumping pressure is maintained.

In a conventional ball valve a spherical ball surface segment makes an annular outer seal which fully closes or blocks the opening of a single pipe. In the present valve there is an additional inner pipe (inner tube 882 of the union) defining its own inner conduit. If the side surface of the valve ball is spherical, it will substantially close off the end of the inner pipe in the closed position although it will not fully seal it unless special measures are taken. As in the open position, a degree of leakage at this position is not serious. However in the present systems, a flow which continuously circulates by communication between outflow and return conduits is of special value because it enables sanitary operation. A further feature here is therefore to provide, in the side (sealing) face of the ball member 861 on one or both sides thereof, a recessed portion 868 (recessed relative to a spherical shape envelope, such as for example a flat region) as indicated in dotted lines. In the closed condition, the recessed portion 868 is spaced away from the end of the inner union tube 882 and puts the outflow and return conduits into communication for substantial flow between the inner and outer conduits on that side of the valve, although the valve as a whole remains completely closed by the outer seals 881. This enables the branch conduit - which might otherwise become static and non-sanitary - itself to maintain a circulating flow although the user point is out of operation, so that the whole system maintains operational effectiveness .

Figs. 10 to 13 show an alternative embodiment of isolation valve from which the movable member is a cylindrical plug 761, fitting in a cylindrical socket of the valve body. The cylindrical plug can fit in a uniform-section bore crossing the pipe axis, so that the valve housing can be a simple block with a transverse bore open at one side. This represents a potential simplification relative to a spherical ball member. A top bonnet plate (Fig. 10) mounting the operating spindle and closing the system with seals is secured over the opening. The general principle of operation of the plug closure body is the same as with the ball. As before, side recessed portions 768 (recessed relative to the cylindrical surface) are provided on the valve body so that in the closed condition, there is flow communication between the inner and outer conduits on the same side. The fitted unions (Fig. 13) are the same in principle except that their inner faces are shaped to complement a cylindrical form. As before, the unions may provide the seal integrally, or separate seal members may be inserted.

It may be mentioned that in the ball valve and plug valve described here, the various elements may be made from metal e.g. copper, steel, or from engineering plastics, according to practicality .

Figs. 14 to 16 show an alternative embodiment of the plug-type valve with a cylindrical closure member, the body having an octagonal exterior form. Figs. 17 and 18 show an alternative isolation valve embodiment, a ball valve as in the first isolation valve embodiment but showing an alternative in which sealing of the valve is by discrete polymeric sealing rings inserted to either side of the ball, separate from the union tubes (not shown).

Fig. 19 shows schematically how the functions of the commissioning regulator and the isolation valve can be combined into a single device. The figure shows, in cross- section, an isolation valve ball closure member with features as seen in e.g. the embodiments of Fig. 9 and Fig. 17. The ball is formed in two separate halves to be bonded together (this can indeed be the manner of producing the ball valve members in the earlier embodiments). Side recesses are provided as before. Between the two halves of the ball closure member an inner spindle is fitted, through opposed holes on opposite sides of the inner tube so as to be rotatable. The inner spindle carries a circular vane, sized to occupy most of the internal cross-section of the inner tube when perpendicular to its axis so it can act as the occlusion member of a commissioning regulator in the manner described above. The skilled person will understand that a modified valve closure member such as that shown in Fig. 19 can be incorporated into an isolation valve. The inner spindle which operates the regulator vane can be controlled through a separate actuator shaft, coaxial with the actuator which turns the valve closure body in the valve housing.

The illustrated embodiments show the commissioning regulator adjacent to or combined with an isolation valve.

The skilled person will appreciate that the function of occluding flow, such as return flow, can be provided with a commissioning valve at any point along the combined pipe (double pipe) of a secondary circuit or branch.

Fig. 20 shows options for connections of the combined pipe. Fig. 20(a) shows a T-joint of confluence type, where the flows in a combined pipe are "converted" to separate flows in single pipes. The main T-member has an outer wall opening for branching out the inner pipe, into which an adaptor having a supplementary smaller end spigot can be inserted. This adaptor converts between a single pipe of an intermediate diameter (larger than the inner pipe, smaller than the outer pipe) and the diameter of the inner pipe, which is also the diameter of a tubular angle piece into which the end spigot of the adapter is fitted to hold it in position inside the joint.

Fig. 20(b) shows a T-joint for combined pipe in which all three arms are of combined pipe structure, and showing a preferred arrangement in which the flow in the inner conduit of the side arm (branch) of the T has a curve following its intended flow direction, so that the flow from the branch direction (vertical in Fig. 20(b)) joins the inner conduit of the main combined pipe (right-to-left in Fig. 20(b)) through a gradual radius, the inner pipe segments merging non perpendicularly .

Finally Fig. 21 shows schematically a connector for use where a combined pipe meets a fitting such as a tap where a single hot flow is expected. This is essentially an adaptor where the inner conduit terminates at an opening short of the end of the outer pipe, the end of the inner conduit being supported by radial supports as shown. When the tap (not shown) is open, outflow water continues through the adaptor in a single direction. When the tap is closed, water from the outflow conduit is reversed in direction and returns through the central inner (return) conduit as shown.

While embodiments have been shown and described to illustrate and explain the invention, the skilled person will appreciate that variations can be made based on the skilled person's knowledge while using features and advantages of the novel teachings herein, and such variations are encompassed by the general teaching herein and the appended claims.