WO2008093082A1

WO2008093082A1 - Circulating flow device

Info

Publication number: WO2008093082A1
Application number: PCT/GB2008/000312
Authority: WO
Inventors: Michael Ogden
Original assignee: TEMPERATE SYSTEMS Ltd
Current assignee: TEMPERATE SYSTEMS Ltd
Priority date: 2007-01-30
Filing date: 2008-01-30
Publication date: 2008-08-07
Anticipated expiration: 2009-07-30
Also published as: GB0701798D0

Abstract

A circulating flow device is described comprising a re-circulation and temperature control means for water from a domestic bath. The device is a fluidly continuous conduit having an inlet at a first end to receive water from a domestic bath in use and an outlet at a second end to pass water having been circulated through the assembly to a domestic bath in use; said assembly including: an impeller to drive water through the fluidly continuous conduit; a heater acting on water passing through the fluidly continuous conduit to apply heat to raise temperature of the water passing through the fluidly continuous conduit; a temperature sensor to measure the temperature of water passing through the fluidly continuous conduit; a data register to store at least a target temperature (TT) and a maximum temperature (TMAX); a temperature display means comprising at least a temperature alarm to indicate via audio and/or visual alarm means when TMAX is exceeded; a temperature controller in data communication with the temperature sensor and configured to actuate the heater in response to a signal from the temperature sensor to tend to raise the temperature of the water through the fluidly continuous channel towards TT, and to actuate the temperature display at least by actuating the alarm if the measured temperature exceeds TMAX. A device fitted to the bath and a method of fitment and operation are also described.

Description

Circulating Flow Device

The invention relates to a circulating flow device comprising a means to re-circulate and control the temperature of water in a domestic bath. The invention additionally relates to a bath with such a re-circulating device fitted, and to a method of providing for re-circulation and heating of water in a domestic bath by means of fitment or operation of such a device, either at the time of manufacture or as an aftermarket modification.

The invention relates to domestic baths of the type which are provided for use in conjunction with domestic hot water installation, in particular being sized for use indoors in a domestic bathroom typically by a single user, for example comprising a receptacle for domestic hot water with a capacity of the order of 75 to 200 litres.

It is a feature of domestic baths of this size and function that they tend to be filled on demand. In this regard, they contrast with larger facilities, such as public bathing facilities, and even larger private facilities such as might be described as domestic hot tubs or the like, where the bath is filled and brought to temperature prior to use, rather than simply on demand. Conventional small domestic baths in contrast are filled at the time of use from a domestic hot water supply.

A typical domestic hot water supply maintains hot water in a suitable storage tank or the like at a temperature which is considerably higher than that which will be comfortable for domestic bathing. Accordingly, drawing a bath on demand at a desired temperature requires careful control of water supply to supply a mixture of high temperature water from the domestic hot supply with a quantity of cold water from a domestic cold supply. If this mixing process is not carried out carefully, the resultant drawn bath will not be at a satisfactory temperature, and in particular if too much hot water is drawn, the resultant bath could be dangerously hot and constitute a scald hazard.

In part because of this, it is becoming increasingly common to find safety legislation introduced in domestic facilities which limits the temperature at which hot water can be drawn from a domestic supply when filling a bath, for example requiring safety apparatus taking the form of a mixer tap assembly or a like device which mixes the hot and cold supply itself, and provides a single drawn water supply to fill the bath which is at a reduced, safer temperature. The mixer device may for example use a thermostatic control with a pre-set safe maximum temperature.

For example, recent building regulations introduced in Scotland demand that in new build or during major alterations that include bathroom facilities, the facility must incorporate a temperature control associated with the hot water supply to the bath set to maximum of 48 ° C. Since the basic domestic supply will inherently be hotter than this (indeed, is obliged to be hotter than this for hygiene reasons, the same Scottish regulations specifying that the heater must run at at least 6O⁰C and the circulation system should circulate at no less than

55 ° C) this represents a significant reduction in the supplied temperature compared with direct domestic hot water supply.

This reduces the scalding hazard, but has implications for maintaining the desired bath temperature. Typical desired domestic bathing temperatures are in the region of 39 ° C to 42 ° C. Typically, in a domestic situation, when the temperature of the bath has fallen below a comfortable level, a user will simply draw more hot water. Clearly, it is much easier to bring the bath up to temperature if hot water can be drawn at 60 ° C or more than if hot water can only be drawn at no more than 48 ° C.

Furthermore, regardless of the temperature at which further hot water might be drawn to bring a bath back up to temperature, a further issue is raised if the bath is already relatively full. A domestic user will be obliged in this situation to let some of the cooler water out in order to accommodate the freshly drawn hot water. The cooler water is typically only just below a desired temperature, and retains a lot of residual heat. This is a very wasteful process.

For this reason, domestic bath users who like to enjoy a sustained period in the bath, and are therefore likely to find that during that sustained period the water temperature will fall below what they find desirable, will typically bring the water back up to temperature in a manner which is inefficient and wasteful. This problem is only likely to be exacerbated if safety regulations reduce the temperature at which domestic hot water can be drawn into a domestic bath.

It is an object of the invention to mitigate some or all of the above disadvantages in bathing systems, in particular in the relation to maintenance of a desired bathing temperature for a sustained period.

It is a particular preferred object of the invention to provide a means to circulate and control water temperature in a domestic bath by which the temperature can be controlled in a more energy efficient manner.

It is a particular preferred object of the invention to provide a means to control water temperature in a domestic bath which is conveniently compatible with safety mechanisms that limit the temperature at which water can be drawn to fill the bath.

Thus, in accordance with the invention in the first aspect there is provided a circulating flow device comprising a re-circulation and temperature control means for water from a domestic bath, which device comprises an assembly defining a fluidly continuous conduit having an inlet at a first end to receive water from a domestic bath in use and an outlet at a second end to pass water having been circulated through the assembly to a domestic bath in use; said assembly including: an impeller to drive water through the fluidly continuous conduit; a heater acting on water passing through the fluidly continuous conduit to apply heat to raise temperature of the water passing through the fluidly continuous conduit; a temperature sensor to measure the temperature of water passing through the fluidly continuous conduit; a data register to store at least a target temperature (TT) and a maximum temperature (TMAX); a temperature display means comprising at least a temperature alarm to indicate via audio and/or visual alarm means when TMAX is exceeded; a temperature controller in data communication with the temperature sensor and configured to actuate the heater in response to a signal from the temperature sensor to tend to raise the temperature of the water through the fluidly continuous conduit towards T_τ, and to actuate the temperature display at least by actuating the alarm if the measured temperature exceeds TMAX.

The assembly of the invention provides an efficient and effective way to maintain domestic bath water temperature. The water is drawn at the time of use, either at or about a suitable temperature from a temperature limited single supply system, or by mixing streams from a domestic hot and a domestic cold supply. In this regard, the bath is filled in an entirely conventional manner by drawing hot water on demand, which is in contrast to the typical mode of operation for larger facilities, including larger domestic facilities such as hot tubs, where water is drawn and the bath filled as an initial preparatory exercise, and is brought to and maintained at temperature until such time as it needs to be used, perhaps generally in anticipation of such use but not specifically on demand.

However, the simple circulating system of the invention confers significant advantages in relation to getting and maintaining a desirable bathing temperature in the domestic bath when compared with traditional methods which involve merely drawing hot and/or cold water from the domestic supply as and when the comfort level of the bather suggests it to be demanded.

First, water can be heated as it is circulated. Thus, once a bath is drawn at a desired temperature it can be maintained at that temperature by the action of the heater in line in the fluidly continuous conduit of the assembly in response to temperature measurements at the temperature sensor and under the action of the temperature controller. Maintenance of temperature is both automatic and energy efficient. No user intervention is required to draw further hot water to raise the temperature of a cooling bath. Moreover, the temperature maintenance procedure is fundamentally more efficient, when compare with the likely way in which a bather will maintain temperature of a cooling bath in conventional manner, by allowing some cooler water (but water which still retains substantial residual heat) to flow to waste in order to provide room to draw some fresh hot water. Moreover, the heating system addresses concerns which might arise as safety regulations are tightened and it thus becomes harder to raise the temperature of a cooling bath because the temperature differential between the bath and the reduced permitted hot water supply temperature is less. Additionally, by incorporating a temperature alarm system in conjunction with the temperature sensor, an important safety feature is provided. A maximum safe temperature can be set, and some form of alarm activated, for example in the form of a visual warning, an audible warning, or some combination of the two, when this is exceeded (or exceeded or approached by a predetermined amount) as a T is reached corresponding to the TMAX in the data register. This provides an additional safety feature. Thus, a bath fitted with the system of the invention exhibits a much reduced scald hazard, both since it will alert the user if the initial temperature is to high, and also since it will not require a user whilst in the bath to draw from a hot water supply to raise the temperature of the bath.

Considering the mode of operation with reference to particular example temperatures, it can be supposed that a maximum alarm temperature might be set at, say, 46⁰C. For most adult bathers, a comfortable temperature might be in the range of 38 to 41⁰C. A child bather might require a slightly lower temperature. The data register may be configured to store a preset upper limit as TMAX, or to allow a user to input a T_MAX (or to input a figure from which a TM_AX is calculated on a functional basis).

The data register is preferably configured at least to allow a user to enter the lower figure or range as Tj (or to input a figure from which T_τ is calculated on a functional basis). The data register may store a desired temperature range as T_τ, or may calculate a desired temperature range functionally related to, and for example centred on, an input T_τ.

In one mode of operation, water is initially drawn at the desired temperature, and may simply be tested by the bather in conventional manner. As the bather uses the bath, the system circulates water through the fluidly continuous conduit and measure the temperature of the circulating water. As the temperatures falls below a temperature determined by reference to TT (which when used herein encompasses the lower bound of a range represented by a target temperature or some functionally related threshold value related to a target temperature) the heater is activated and re-circulating water is reheated until such time as the desired temperature (or some second functionally related threshold valve) is reached. The temperature control thus serves as a thermostatic control as water is re-circulated through the fluidly continuous conduit.

In an alternative mode of operation, the drawing process can be dispensed with entirely, with the device of the invention itself drawing water on demand. In this example, the device of the invention includes a water supply inlet assembly comprising an additional inlet or inlets to draw water directly from a domestic water supply, and to pass the same to the outlet of the fluid continuous conduit. In this mode of operation, the bath is filled by actuation of suitable control means on the device of the invention to draw water from the domestic supply. Conveniently, the water supply inlet assembly includes a thermostatic control means to draw water from the supply at or about the target temperature.

For convenience, in a preferred embodiment, this thermostatic control means make use where possible of existing features of the device of the invention, and in particular for example makes use of the temperature sensor of the device. For example, in one possible embodiment, the water supply inlet assembly comprises an inlet for connection to a domestic hot water supply, an inlet for connection to a domestic cold water supply, a mixing assembly to mix the two supplies as water is drawn therefrom, an operable closure valve on each of the inlets operable to selectively limit each of the said supplies therethrough, a temperature sensor downstream of the mixer assembly to measure the temperature of water being drawn from the domestic supply, and supply inlet control means in data communication with the temperature sensor and configured to selectively operate the closure valves to cause the supplied water temperature to approximate to the target temperature.

In accordance with this mode of operation, the modified device is actuated to draw water, and is for example programmed with a desired water temperature, and then draws water from the domestic supply at or about the desired temperature. It then maintains the water in the same manner as above. The display means may include a "bath ready" display for such mode of operation.

An impeller is provided in line in the fluidly continuous conduit, in the sense that it comprises at least impeller means acting on the water passing through the fluid continuous conduit, to draw water into the inlet and pass it to the outlet. The impeller is for example a pump such as a rotary pump. Conveniently, the rotary pump is a rotary electric pump.

It is not the intention that the impeller generates a whirlpool, spa or Jacuzzi effect. The device is intended for use in a conventional domestic bath, where significant levels of agitation of the water are not desirable, and where it is desirable to keep working noise levels to a minimum. The impeller in the device of the invention is intended to operate at relatively very low pressure and low flow rate, for example of the order of 1000 litres per hour or less. It is intended to be discrete, quiet, and merely to circulate the water. This is a much lower flow rate than is typical for, say, a Jacuzzi pump which is likely to operate at least 10,000 litres per hour, to be audible, and by definition and design to agitate the water to a significant degree. The heater applies heat as required under control of the temperature control means to water passing through a heating zone in the fluidly continuous conduit. The heater may work by immersion or radiant heating.

The heater conveniently comprises a heated length of conduit, for example comprising a conduit length such as a conduit tube having a heating element incorporated within or on a surface thereof. In one possible embodiment the conduit length is a thermally transmissive tube having a heating element on an outside surface, and for example surroundingly around the outside surface. The heating element is for example a resistance-heated element, and in a particularly preferred embodiment therefore comprises a resistance-heated sleeve surroundingly disposed about a tube conduit length.

The temperature sensor comprises any suitable sensing means to measure the temperature of water. The temperature sensor may be a contact sensor or a non-contact sensor and may for example be a temperature probe device, a thermocouple, a thermister, a resistance temperature detector, a radiation thermometer, or any other suitable device. The temperature sensor is conveniently a thermocouple wire.

In a preferred mode of operation, the temperature sensor supplies a reading representative of residual temperature of the water in the bath, and accordingly senses temperature of water in the bath volume itself and/or in the conduit at or towards the inlet of the fluidly continuous conduit and upstream of the heater. The temperature sensor is thus preferably adapted to be located in use in the bath volume itself and/or, or in the conduit at or towards the inlet of the fluidly continuous conduit and upstream of the heater. Preferably, the temperature sensor of the device of the invention senses the temperature of water in the bath itself so that it is able to operate, in particular to operate in conjunction with the alarm function, even when the circulating flow device is not fully operational with water being circulated through the fluidly continuous conduit. Additionally or alternatively a sensor may be provided in line in the fluidly continuous conduit. A secondary temperature sensor may be provided downstream of the heater as a safety feature to ensure that water passed back into the bath does not exceed a dangerous level, for example that it does not exceed T_MAX-

A temperature display is provided in the assembly of the invention which comprises at least an alarm comprising an audio and/or visual alarm to display when the temperature of the water exceeds TM_AX. This may mean that it actuates at an input maximum, or that it actuates at an alarm temperature set in functional relationship with an input maximum.

The temperature display preferably displays further information about the temperature detected by the temperature sensor. For example, in one embodiment, the temperature display comprises a display identifying a plurality of digital states, which may include one or more of the following: that the temperature is above a safe level (such as T_MAX), that the temperature is below a safe limit, but above a desired level or range, that the temperature is within a desired range, and that the temperature is below a desired range. A simple display, for example comprising coloured light display means, could effect this.

Additional or alternatively the temperature display might included an alphanumeric display capable of displaying temperatures numerically and/or displaying condition information verbally, for example on the basis of the above listed condition parameters. The temperature display may be adapted to exhibit further information concerning the state of the system, for example including information concerning set target and maximum temperatures.

Preferably, the target temperature constitutes a target range, which may for example be a range of 2 to 3° C. This may be a user-settable range, or the displayable control system may be adapted to calculate a desired range in functional relationship with a pre-set single T_τ, for example setting a target range as input Tj ^± ΔT where ΔT is a desired range parameter being considered to be within the target range.

The assembly further comprises a temperature control means which comprises the data register and the temperature controller.

The data register may include pre-set and/or user input parameters. In particular for example the data register is programmable and/or is pre-set with a target temperature (T_τ) or a target temperature range (TT ^± ΔT) and/or with a maximum temperature (TMAX)- The control means may incorporate both user settable and factory pre-set parameters. These latter may include statutory maximum parameters.

Conveniently, a user accessible control, such as a button or buttons, dials etc, is provided to allow input of and/or adjustment of pre-set parameters. Conveniently, in a preferred embodiment, this is provided in association with an alphanumeric display to show at least pre-set temperatures being set and/or adjusted, and optionally also pre-programmed parameters and/or measured temperature.

The temperature control selectively activates the heater to maintain the temperature at or raise the temperature towards the T_τ (which may be a single figure or a range). For example, the heater is activated if the temperature falls below a T-i, being set as, or in functional relation to, Tγ. The heater switches off if T rises above T₂ similarly set as or in functional relationship to TT.

The controller/sensor combination thus acts in essentially conventional manner as a thermostatic control to maintain the temperature of the circulating water in the fluidly continuous channel, and therefore ultimately in continuous mode of operation to maintain the bath water temperature, at or about TT. The controller/sensor combination further acts to trigger an alarm if T_MAX is exceeded.

The assembly of the invention is thus both a means to maintain temperature automatically without the need to draw fresh hot water once a user is in the bath, and a means to ensure that the bath does not initially or subsequently exceed a safe temperature level. In both respects, it confers significant safety and efficiency features.

The assembly optionally further includes a filter at the inlet and/or the outlet. Such a filter may be a mesh filter, a percolation filter, a dynamic fluid filter or the like. This filter allows circulating water to be kept free of debris, avoiding fouling of the circulation system.

The assembly preferably incorporates a hygiene unit having a function to sterilise water in the fluid continuously channel. For example, the hygiene unit may comprise a UV light source, a chemical exchange system or the like acting on water in stream.

The assembly preferably includes a suitable power supply, which is for example a suitable battery power supply. The battery is conveniently re- chargeable. Alternatively, a mains supply, suitably protected, and for example with a suitably stepped down voltage given the environment of operation, might be considered.

The system conveniently includes an on/off switch, and in particular separate on/off switches for the circulating flow elements, for example serving to actuate the impeller and/or heater, and for the static elements of the system. In this way the system can have two operational modes, in a simple operational mode as a stand alone safety/feedback system to give an alarm when an excessive temperature is reached, and in a full operational mode as a full temperature control system with the flow mechanism and heater activated.

In accordance with a further aspect of the invention, a domestic bath is provided fitted with a circulation device in accordance with the first aspect of the invention, in that a first aperture is provided in a wall of the bath to put an inlet of the device in fluid communication with the bath volume at below a typical desired water level, and a second aperture is provided in the wall of the bath to put an outlet of the device in fluid communication with the bath at below the desired water level. Conveniently, the device is disposed generally horizontally, in that inlet and outlet are roughly at the same level on the bath.

In accordance with a further aspect of the invention there is provided a method of re-circulating and maintaining the temperature of water in a filled domestic bath, the method comprising providing a device in accordance with the first aspect of the invention in fluid communication with the internal volume of a domestic bath containing water, and activating the device to re-circulate the water in the manner above described. That is, the method comprises at least activating the device to re-circulate the water by causing the impeller to drive water from the inlet through the fluidly continuous conduit to the outlet; measuring the temperature of the recirculating water and on the basis of such measurement: heating the water as required by operating the heater acting on water passing through the fluidly continuous conduit raise temperature of the water passing through the fluidly continuous conduit in such manner as to tend to raise the temperature of the water through the fluidly continuous channel towards a target temperature; if necessary actuating the temperature display at least by actuating the alarm if the measured temperature exceeds T_MAX.

The method conveniently further involves initially filling the bath by drawing water from a domestic supply, and also conveniently further involves programming suitable temperature parameters into the data register. Other features of the method will be understood by analogy.

In accordance with a further aspect of the invention there is provided a method of modifying a domestic bath, for an example as a production or aftermarket modification, which comprises providing apertures in the bath wall at a suitable level below an intended waterline, and fluidly connecting the inlet and the outlet of a device in accordance with the first aspect of the invention respectively to the inlet and to such apertures.

The invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 illustrates a typical temperature profile for a typical domestic bath;

Figure 2 illustrates a device in accordance with an embodiment of the invention; Figure 3 illustrates the device of figure 2 fitted to a domestic bath. Figure 1 illustrates a typical temperature drop in a domestic bath for water initially at a temperature around 43⁰C. Four series of data are shown. These are set out in Table 1 and plotted on figure 1.

1 42.8 42.6 42.1 41.8 41.3 41.1 40.6 40.4 39.9 39.5

2 42.8 42.5 42.1 41.7 41.2 40.8 40.5 40.1 39.8 39.5

3 43.0 42.5 41.8 41.2 41.0 40.6 40.1 39.7 39.3 39.0

4 43.0 42.4 41.9 41.4 40.9 40.3 40.0 39.6 39.4 38.9

Table 1 : Temperature drop data: 4 series; intervals of one minute

In each instance, the water temperature falls off quite rapidly. Bathers are quite temperature sensitive, and whilst desirable temperature might vary with mood and ambient condition, for a given mood and ambient condition it is likely to remain in a fairly narrow range, with an optimum range perhaps as little as 1⁰C, and a comfortable range perhaps as little as 3⁰C.

It can be seen from the figure that temperature remains within half a degree of a desired 41⁰C bathing temperature for only around two minutes, represented on the time axis by the range R. Many bathers prefer to bathe for a much longer period than this, and are therefore likely repeatedly to need to adjust the temperature of the water as they bathe.

Typical for example they will let out some water to waste and refill with freshly drawn hot water. This is wasteful and is likely to become increasingly difficult as hot water supply temperatures are reduced for safety reasons.

Figure 2 illustrates a circulating device in accordance with the invention and is conveniently referred to in conjunction with figure 3 in which such a device 11 is shown disposed on the side of a conventional domestic bath 12 so as to be in fluid communication with water within the bath below a water level W via an inlet and an outlet in the bath wall.

Referring specifically to figure 2, a device comprises a system inlet pipe 1 in fluid communication with an inlet aperture in the wall of the bath and through which water from the bath can be drawn, a safety flow switch 2 and an inlet temperature sensor 3. The inlet temperature sensor is in data communication with the main control electronics within the housing 9, and provides a means for measuring the temperature of water being drawn into the device, and thus thermostatically controlling the heating mechanism. Additionally or alternatively, a further sensor (not shown) may be provided within the bath volume to measure water temperature in the bath even when water is not flowing through the device 11.

Water continues along the fluidly continuous conduit into the glass heating tube. The heating tube consists of a generally thermally transmissive, and for example, glass tube 10 about which is wound a resistance heated element 4. The heated element surrounds the outer surface of the tube, and heats water flowing through the tube primarily in radiant manner. The heating element is under control of suitable control electronics in the housing 9, which are actuated by response to the signal from the temperature sensor 3 and/or temperature sensor measuring bath water temperature to switch the heater on when temperature falls below a predetermined level such as in necessary to attempt to maintain water in the desired temperature range.

Downstream of the heater assembly is a UV filter tube 5 which effects a degree of sterilisation of the circulating water. The device is particularly intended to facilitate prolonged domestic bathing by a user, and this therefore provides a useful additional safety feature.

Reheated and suitably sterilised water is then passed via the outlet tube 6 through an aperture in the side wall of the bath 12 and back into the bath volume. By continuous operation of this circulating device bath water temperature can be maintained at a steady state level for as long as desired. An outlet temperature sensor 7 is provided as a safety feature.

Circulation through the device is by means of the re-circulating pump 8.

The system further includes a display panel 15 which incorporates a temperature display on a liquid crystal device low profile feedback panel 16, and includes programmable means in the form of the buttons 17 to allow a user to input at least a desired temperature or range. A maximum temperature may similarly input or may be pre-set. Temperatures are stored in a data register as part of the control electronics in the housing 9.

The panel includes an alarm panel 18 which incorporates visual display LEDs 19 capable at least of giving a excessive temperature alarm, and optionally also of giving indications of other states (ready, too cool etc) and further incorporating (not shown) an audio alarm.

The system will have two modes of operation. In its full mode of operation it will operate as a control system with full flow through the device 1 1 and with the heater operational to maintain a constant temperature in the bath. In a simple mode of operation, the safety alert can stand-alone.

In use in the illustrated embodiment water is drawn from a conventional mixer tap 13 to a water level W, although as set out above, in an alternative embodiment, the system 11 may be modified to include direct connection to the domestic water supply. In these circumstances, a lateral extension of the inlet tube 1 extends beyond the point where there is an inlet to the bath 12 and connects directly to the domestic hot water supply, obviating the need for the tap. For example, connection is via a mixer assembly through separate valve controlled inlets to the hot and cold water supplies. The bath is then filled by drawing water through the inlet tube 1 at an appropriate temperature, with feedback from the temperature sensor 3 under action of control electronics in the housing 9 being used to control the supply inlet valves as appropriate to maintain the temperature of the water filling the bath.

In either instance water is filled to suitable fill level, W, and the system is then able to operate.

In a default mode of operation, even when the circulating flow part of the device is not operating the system will incorporate a safety temperature feedback loop, such that at a suitable alarm temperature, such as for example 42.5⁰C, a red for danger LED 19 will illuminate, then intermittently flash having effect of back lighting the display panel and indicating danger, and a sound alarm will give a audible alert to the water temperature danger. To facilitate this, the system will conveniently incorporate a thermocouple wire which will provide feedback temperature in relation to the liquid with the bath. The wire will terminate at one end with a rivet style flat metallic stud or similar which will in turn be fixed into the bath under the minimum level water line W. The wire will terminate as a loose wire which can be run inside the bath down into the water to enable freestanding usage. The simple mode of operation may be battery-powered. However, the invention is primarily intended for operation as a full thermostatic control system for the re-circulating heating flow. In this mode of operation, the system will continue to incorporate a safety temperature feedback loop associated with a pre-set maximum temperature as above described. Again, the LED will illuminate and the sounder will give an audible alert. With the system in operation this should only ever be activated if the bath source temperature has initially been provided at to higher temperature, and will inform the prospective bather of the danger. The safety features in the device should otherwise prevent temperature rising to this level.

For full mode of operation the system will preferably not draw on a battery but will instead take power via a low voltage connection to the main control system unit. In this mode of operation a thermocouple wire will terminate inside the warm water outlet of the system thus reading the temperature of the just warmed water. A secondary sensor will monitor the actual temperature of the system inlet water prior to heating. This sensor will provided the actual temperature reading on the display gauge and can also act as system diagnostic check for heater tube efficiency.

Operating within the limits set by the operator via the display panel the control board system electronics within the housing 9 will operate with mains input, providing a low voltage output feed for the sensor display system. The switching/relaying of power to various parts of the operating system otherwise will be provided at mains voltage. All settings to the various system components will be either "on or off" within the various modes of operation, with suitable operative connections such that for example if the flow system is in an on position then the pump, heater element and UV filter will be in an on state. When the desired temperature is reached, the heater will switch to off until the source temperature indicates a 0.5⁰C fall, at which point the heater will return to an on state.

If the system is in its on state then the water pump will operate continuously. Only when the system is physically turned off by the operator will the pump cease operation, except that the system will be provided with a safety feature comprising a flow metering means and switch that indicates when water is no longer flowing through the system (for example it has been inadvertently been drained from the system without switching off), and in those circumstances the whole system will immediately shut down.

After five minutes without user interaction, and once this flow switch has deactivated the unit, the system is programmed to assume that the operator has simply drained the bath and forgotten to switch off the system and is programmed to switch off and go into standby mode.

The system operates with a time cycle delay of for example one to two minutes from the pump starting its operation to the heating element being switched on even if temperature readings otherwise require the heater to be on. This time delay provides the heater element with a safety period to ensure that a good and air free water flow is being achieved through the heating element before it is switched on. This is important as if the heating element is on in an open state (that is, without adequate water flow) then the heating element is likely to burn out.

The LJV element will be in permanently on state while the pump is in use, and will conveniently continue to be in an on state for a time period of, say, five to seven minutes after the pump ceases to operate to maintain disinfectant effect.

The system will incorporate a safety cut-out via a flow switch should the flow of water be interrupted or stopped for any reason.

The system in its full mode of operation thus provides a safe and energy efficient means by which water can be maintained at a desired temperature over a sustained period in a domestic bath.

Claims

1. A circulating flow device comprising a re-circulation and temperature control means for water from a domestic bath, which device comprises an assembly defining a fluidly continuous conduit having an inlet at a first end to receive water from a domestic bath in use and an outlet at a second end to pass water having been circulated through the assembly to a domestic bath in use; said assembly including: an impeller to drive water through the fluidly continuous conduit; a heater acting on water passing through the fluidly continuous conduit to apply heat to raise temperature of the water passing through the fluidly continuous conduit; a temperature sensor to measure the temperature of water passing through the fluidly continuous conduit; a data register to store at least a target temperature (TT) and a maximum temperature (TMAX); a temperature display means comprising at least a temperature alarm to indicate via audio and/or visual alarm means when T_MAX is exceeded; a temperature controller in data communication with the temperature sensor and configured to actuate the heater in response to a signal from the temperature sensor to tend to raise the temperature of the water through the fluidly continuous channel towards T_τ, and to actuate the temperature display at least by actuating the alarm if the measured temperature exceeds T_MAX.

2. A circulating flow device in accordance with claim 1 wherein the data register is configured to allow a user to input a T_MAX or to input a figure from which a TMAX is calculated on a functional basis.

3. A circulating flow device in accordance with claim 1 or claim 2 wherein the data register is configured to allow a user to enter a figure or range as TT or to input a figure from which Tj is calculated on a functional basis.

4. A circulating flow device in accordance with any preceding claim further comprising a water supply inlet assembly comprising an additional inlet or inlets to draw water directly from a domestic water supply, and to pass the same to the outlet of the fluid continuous conduit.

5. A circulating flow device in accordance with claim 4 wherein the water supply inlet assembly comprises an inlet for connection to a domestic hot water supply, an inlet for connection to a domestic cold water supply, a mixing assembly to mix the two supplies as water is drawn therefrom, an operable closure valve on each of the inlets operable to selectively limit each of the said supplies therethrough, a temperature sensor downstream of the mixer assembly to measure the temperature of water being drawn from the domestic supply, and supply inlet control means in data communication with the temperature sensor and configured to selectively operate the closure valves to cause the supplied water temperature to approximate to the target temperature.

6. A circulating flow device in accordance with any preceding claim wherein the impeller is a rotary electric pump.

7. A circulating flow device in accordance with any preceding claim adapted to operate at a through flow rate of the order of 1000 litres per hour or less.

8. A circulating flow device in accordance with any preceding claim wherein the heater comprises a heated length of conduit.

9. A circulating flow device in accordance with claim 8 wherein the heater comprises a conduit tube having a heating element incorporated within or on a surface thereof.

10. A circulating flow device in accordance with claim 9 wherein the heater comprises a thermally transmissive tube having a heating element on an outside surface, and for example surroundingly around the outside surface.

11. A circulating flow device in accordance with claim 9 or 10 wherein the heating element is a resistance-heated element.

12. A circulating flow device in accordance with any preceding claim wherein the temperature sensor comprises a contact sensor in the form of a thermocouple wire.

13. A circulating flow device in accordance with any preceding claim comprising a primary temperature sensor adapted to be located in use in the bath volume itself and/or in the conduit upstream of the heater and a secondary temperature sensor adapted to be located downstream of the heater to ensure that water passed back into the bath does not exceed T_MAX-

14. A circulating flow device in accordance with any preceding claim wherein the temperature display is adapted to display further information about the temperature detected by the temperature sensor by identifying a plurality of digital states, including one or more of the following: that the temperature is above a safe level (such as TMAX), that the temperature is below a safe limit, but above a desired level or range, that the temperature is within a desired range, and that the temperature is below a desired range.

15. A circulating flow device in accordance with any preceding claim wherein the temperature display is an alphanumeric display adapted to display temperatures numerically and/or condition information verbally

16. A circulating flow device in accordance with any preceding claim further comprising a user accessible control to allow input of and/or adjustment of temperature parameters.

17. A circulating flow device in accordance with any preceding claim further comprising a filter at the inlet and/or the outlet.

18. A circulating flow device in accordance with any preceding claim further comprising a hygiene unit having a function to sterilise water in the fluid continuously channel.

19. A domestic bath fitted with a circulation device in accordance with any preceding claim, in that a first aperture is provided in a wall of the bath to put an inlet of the device in fluid communication with the bath volume at below a typical desired water level, and a second aperture is provided in the wall of the bath to put an outlet of the device in fluid communication with the bath at below the desired water level.

20. A method of re-circulating and maintaining the temperature of water in a filled domestic bath comprising: a. providing a device in accordance with any of claims 1 to 18 in fluid communication with the internal volume of a domestic bath containing water; b. activating the device to re-circulate the water by causing the impeller to drive water from the inlet through the fluidly continuous conduit to the outlet; c. measuring the temperature of the recirculating water and on the basis of such measurement: i. heating the water as required by operating the heater acting on water passing through the fluidly continuous conduit raise temperature of the water passing through the fluidly continuous conduit in such manner as to tend to raise the temperature of the water through the fluidly continuous channel towards a target temperature; ii. if necessary actuating the temperature display at least by actuating the alarm if the measured temperature exceeds T_MAχ.

21. A method of modifying a domestic bath, for an example as a production or aftermarket modification, which comprises providing apertures in the bath wall at a suitable level below an intended waterline, and fluidly connecting the inlet and the outlet of a device in accordance with any one of claims 1 to 18 respectively to the inlet and to such apertures.