GB2445061A

GB2445061A - A Bathing Pool with at least three Recirculating Pumping Modes

Info

Publication number: GB2445061A
Application number: GB0722799A
Authority: GB
Inventors: Nabeel Shirazee; Praveen Choudhary
Original assignee: Electronica Products Ltd
Current assignee: Electronica Products Ltd
Priority date: 2006-12-22
Filing date: 2007-11-21
Publication date: 2008-06-25
Anticipated expiration: 2027-11-21
Also published as: GB0722799D0; GB0625571D0; GB2445061B

Abstract

A bathing pool comprises a bathing area 11 for containing a volume of bathing water, a water outlet 12 coupled to the bathing area, a water inlet 19 in the form of a jet directed into the bathing area, a pump connected between the outlet and inlet via a flow duct, a variable speed electric motor 17, preferably a permanent magnet brushless DC motor, for driving the pump 16, a filter 14 connected in series with the duct, and a control unit 23 for connecting to a power source, the control unit has at least three different modes of motor/pump speed operation. Preferably the controller is linked, optionally by a wireless link 29, to a control pad 25 which has a plurality of buttons 27 and a display 26. Emergency stop and audio warnings may be provided. Timer control may also be linked to the pumping modes. Also fault diagnosis could be obtained via a link 29 to a computer.

Description

Bathing Pool This invention relates to a bathing pool, such as a

swimming pool or spa bath.

Spa baths or so-called aerated spas, hot-tub spas, Jacuzzi spas, Whirlpool spas.

Whirlpool baths, hot-tub baths or Jacuzzi baths are becoming increasingly popular in dwellings, hotels, health clubs, leisure centres and the like. Typically spa baths comprise a self-contained body of warm water and are designed for sifting rather than swimming. The water temperature is kept between 30 and 40 deg. C and hydro-jets inside the spa direct water around the user. Larger spa baths or so-called swim spas are known which comprise water jets that produce a flow against which a person can swim without moving.

A typical spa bath comprises a plurality of recirculating pumps arranged to pump respective jets of water into the bathing area of the bath when the latter is activated by the user. Each pump comprises a single-phase induction motor. However, one of the pumps comprises a two speed single-phase induction motor, which can periodically be activated at low speed in order to provide a periodic filtering facility.

Single-phase induction motors require starting capacitors.

Hitherto, there have been several instances of the pumps of spa baths catching fire and the problem has been traced to the capacitors in the two speed single phase induction motors, which eventually break down under the constant starting and stopping performed by the pump.

In order to overcome the above-mentioned problem, one type of spa bath has been produced in which the dual speed pump is replaced by two pumps, one for driving the jet and one for providing the periodic filtering facility.

It is known that people can catch Legionnaires disease from exposure to contaminated water droplets. Air-conditioning systems (including cooling towers), and hot and cold water systems in buildings are common sources of Legionnaires disease. However, users of spa baths can also be at risk from catching Legionnaires disease, as well as other bacterial infections, if the spa has not been treated correctly at the recommended intervals on a regular basis.

Legionnaires disease is a potentially fatal form of pneumonia caused by the Legionefla bacteria. There are several pneumonia-like diseases caused by different types of Legionella bacteria, known as LegioneHosis. The bacteria can survive at low temperatures, although will not multiply. However, at 20 -45 deg. C they thrive and readily multiply. There have been several outbreaks of Legionnaires disease with the causes traced back to a spa bath. Not only can people be exposed whilst using a spa bath, but also by being close enough to breath in the fine spray created by the jets and bubbles.

Legionella are a particular problem in spa baths because: (a) The water is at an optimum temperature for the bacteria to grow; (b) Dirt, dead skin cells etc from the people using spa baths accumulate, providing food for the bacteria to grow; (c) The ducting for the air and water circulation provide a large surface area for the bacteria to multiply; and (d) The aerated water forms aerosols and sprays, via which the bacteria can be breathed in.

Hitherto, there have been various proposals to help reduce the risk of Legionnaires disease. One proposal is continue to use a dual speed pump: the high speed setting is used for the jets (when the spa is in use) and the low speed is activated at regular intervals to provide filter cycles. It is preferable to use the lower speed to agitate the water during the filter cycles, in order to reduce the current consumption and amount of acoustic noise generated by the process.

Another proposal is to use a pump which runs continuously to circulate the water (at a very low speed) throughout the day. Such pumps are much quieter than dual speed pumps. In addition to the low speed pump, there might also be a dual speed pump incorporated into the system and having a high speed for jets and low speed for filter cycles, as mentioned above. The introduction of the low speed pump is however an added precaution against the growth of Legionella.

It will be appreciated that the provision of so many pumps is both costly and complicated. Furthermore, complicated pipe work is required We have now devised a spa bath which alleviates the above-mentioned problems.

In accordance with this invention, there is provided a bathing pool comprising a bathing area for containing a volume of bathing water, a water outlet coupled to the bathing area, a water inlet in the form of a jet directed into the bathing area, a pump connected between said outlet and inlet via a flow duct, a variable speed electric motor for driving the pump, a filter connected in series with the duct, and a control unit for connecting to a power source, the control unit being arranged: in a first mode, to continuously operate the pump motor at a low speed to gently circulate water in the bathing area; in a second mode, to periodically operate the pump motor at a higher speed to agitate water in the bathing area; and in a third mode, to selectively operate the pump motor at a yet higher speed to vigorously pump water into the bathing area.

Thus, a typical bathing pool in accordance with this invention comprises only one pump having a variable speed motor, which runs continuously (when the pool is connected to the supply) at low speed to circulate water through the bathing area at a rate of approximately 50 litres a minute, in order to prevent stagnation of the water and hence alleviate the risk of legionella contamination. The low level continuous pumping does not significantly agitate the water and hence contamination may occur in settled areas. However, in the second mode, the pump then periodically circulates water through the bath at a rate of approximately 100 litres a minute, which agitates the whole volume of water and ensures that it completely filtered. In the third mode, when bathing, the pump can be run at higher speeds of approximately 200 litres a minute or more for vigorously driving the or each of the water jets.

The pump thus performs the function of 3 pumps and the cost and complexity of the bathing pool is significantly reduced. Furthermore, the present invention enables a significant reduction in pipe work and ducting, thereby helping avoid the risk of legionella breeding in the pipe work. Indeed, a recent European Directive has indicated that a reduction in pipe work in spa baths is needed.

In one embodiment, the variable speed motor comprises a 3-phase induction motor, the electronic control means comprising an inverter having a single phase input for connecting to the mains supply and a 3-phase output for connecting to respective windings of the 3-phase motor, and means for varying the output of the inverter to control the speed of said 3-phase induction motor.

3-Phase induction motors are more efficient than single phase induction motors and thus have lower running costs. Furthermore, 3-phase induction motors have a longer life than single phase induction motors and do not require capacitor starting.

In another embodiment, the variable speed motor comprises a permanent magnet brushless motor. The motor may comprise a winding divided into a plurality of sections and switch means for selectively connecting the sections of the winding in one of a plurality of different configurations, wherein each section is connected in series and/or parallel with all other sections of the winding.

In spa baths users are able to vary the water speed by closing the jets on the spa whist the motor continues running at full speed. This so-called throttling causes considerable wear on the motor. We have found that pumps having variable speed motors suffer from reduced wear when exposed to such throttling.

Variable speed motors are more efficient and save the cube of the energy value as the speed is reduced.

The switch means can then be used to change magnetic gears, by changing the configuration of the coil segments in series, parallel or a combination of both, which are connected to the supply. We call such an arrangement magnetic gearing because it utilises the control of the induced back electromagnetic force (back emf) to control the speed by selectively altering the winding configuration which are connected to the supply. This alters the torque with changing speed of the motor.

Preferably the control unit is further arranged, in a fourth mode, to selectively operate the pump motor at a yet higher speed of say 275 litres a minute, in order to pump water even more vigorously through the water jet for a limited duration.

Preferably, the control unit is arranged to activate the pump motor in said second mode at least once during a 24 hour period, the period of activation in said second mode preferably having a minimum duration of say 1 hour.

Preferably the control unit comprises an actuator for stopping the pump motor in the event of an emergency or other situation. Preferably, the control unit is arranged to restart the motor in at least said first mode, once a predetermined period has elapsed following actuation of the actuator. In this way, the water in the pool cannot stagnate after the motor was stopped. Preferably means are provided for indicating that the motor is about to restart: this may be in the form of a countdown timer.

Preferably the control unit comprises an actuator for selecting the third and/or fourth modes of pump motor operation. Preferably, the control unit comprises a memory enabling the third and/or fourth modes of pump motor operation to be programmed.

Preferably, the control unit comprises a display screen, such as an LCD or TFT screen, which can show the mode of operation and/or a menu enabling parameters of operation, such as timing to be programmed or selected. The screen can also be programmed to display operational, technical or other messages such as advertisements.

Preferably, the display screen is arranged to display the mode of operation and/or the menu in a range of selectable languages.

Preferably, the control unit comprises means for connecting it to a remote station, so that it can be programmed remotely and/or so that remote fault diagnosis and maintenance can be carried out. The connection means may comprise a wired or wireless link, for example using a telephone line, cable or GPRS.

Preferably the control unit comprises a terminal for connecting it to a computer for local fault diagnosis or maintenance.

Preferably the control unit comprises means for fault diagnosis of the pool. A common fault with bathing pools is that actuators for selecting modes of operation have a tendency to fail. Accordingly, the control unit is preferably arranged to prompt the user to actuate a particular actuator, the unit being able to determine whether the actuator has been actuated.

Preferably, the pooi comprises an audio output device such as a loudspeaker, the control unit being arranged to drive the device to play warning and/or advertising messages.

Preferably a heater is connected in series with the duct, the heater comprising one or more magnets for conditioning the water to prevent the accumulation of lime scale on the heating element or matrix.

An embodiment of this invention will now be described by way of an example only and with reference to the accompanying drawings in which: Figure 1 is a schematic diagram of a spa bath in accordance with this invention; and Figure 2 is perspective view of the control panel of the spa bath of Figure 1.

Referring to Figure 1 of the drawings, a spa bath in accordance with this invention comprises a large container in the form of a liner 10, which is filled with water to define a bathing area 11 for one or more persons. A first outlet 12 is mounted on a side wall of the liner 10 at a position which is substantially level with the top surface of the water. A second outlet 13 is mounted on a bottom wall of the liner 10. The outlets 12,13 are connected via pipes to a filter 14. The other side of the filter 14 is connected to a heater 15 incorporating an electric heating element and water conditioning magnets. A flow sensor 18 is also mounted on the heater 15. The outlet of the heater 15 is connected to a first pump 16 which is driven by a variable speed permanent magnet brushless dc motor 17. The outlet of the first pump 16 is connected to one or more inlets in the form of jets 19 mounted on the side and/or bottom walls of the liner 10.

Optionally, in a large spa bath, the outlet of the heater 15 may also be connected to a second pump 20 which is driven by another variable speed permanent magnet brushless dc motor 21. The outlet of second pump 20 is connected to further inlets in the form of jets 22 mounted on the side and/or bottom walls of the liner 10.

The or each pump motor 17,21 are electrically connected to a control unit 23. The control unit 23 is connected to the mains supply 24. The control unit 23 is also connected to the heating element of the heater 15 via a mechanical thermal cut-out 31 and to the flow sensor 18 by respective cables.

The control unit 23 comprises a remotely mounted control panel 25 which may be positioned on the top wall of the liner, conveniently within reach of persons in the spa bath. Referring to Figure 2 of the drawings, the control panel 25 is provided with a display 26 and a plurality of control buttons e.g. 27 and indicator lights e.g. 28.

In use, when the control unit 23 is connected to the mains supply 24, the control unit 23 drives the motor 17 of the first pump 16 continuously to circulate approximately 50 litres of water a minute through the bath. This action helps to prevent stagnation of the water in the bathing area 11 and the pipe work. The control unit 23 is programmed to increase the speed of the motor 17 for at least an hour every day, so that approximately 100 litres of water a minute are circulated through the bath. This agitates the water in the bathing area and ensures that settled matter is brought into suspension and carried to the filter 14. The MENU button on the control panel 25 can be actuated to select a mode allowing the length of the period to be increased from 1 hour and also to select the time(s) of day at which the or each period occurs.

In the event of an emergency, the user can press the STOP button to completely stop the motor 17. The motor 17 automatically restarts after a predetermined time period: the length of time remaining is indicated on the display 26. Alternatively, the motor 17 can be started by pressing the DECREASE button several times to reduce the time remaining to zero.

When bathing, the user can press the JET I button to increase the speed of the motor 17, so that approximately 200 litres of water a minute are vigorously circulated through the bath. In the case of larger baths having two or more pumps e.g. 16, 20, the user can press JET 2 and possibly JET 3 to activate the motors of the extra pumps. A BOOST button can be pressed, so that approximately 275 litres of water a minute are very vigorously circulated through the bath for a limited time period.

The control unit 23 comprises an aerial 29 for remotely connecting the unit to a service centre via a GPRS link and the Internet. A connector 30 is also provided on the unit for connecting the control unit 23 to a local computer, so that a technician can perform fault diagnosis and change settings.

A spa bath in accordance with this invention is simple to use, yet does not suffer from the problem of overheating of the pump motor or Legionnaires disease.

Claims

1. A bathing pooi comprising a bathing area for containing a volume of bathing water, a water outlet coupled to the bathing area, a water inlet in the form of a jet directed into the bathing area, a pump connected between said outlet and inlet via a flow duct, a variable speed electric motor for driving the pump, a filter connected in series with the duct, and a control unit for connecting to a power source, the control unit being arranged: in a first mode, to continuously operate the pump motor at a low speed to gently circulate water in the bathing area; in a second mode, to periodically operate the pump motor at a higher speed to agitate water in the bathing area; and in a third mode, to selectively operate the pump motor at a yet higher speed to vigorously pump water into the bathing area.

2. A bathing pool as claimed in claim 1, in which the variable speed motor comprises a 3-phase induction motor, the electronic control means comprising an inverter having a single phase input for connecting to the mains supply and a 3-phase output for connecting to respective windings of the 3-phase motor, and means for varying the output of the inverter to control the speed of said 3-phase induction motor.

3. A bathing pool as claimed in claim 1, in which the variable speed motor comprises a permanent magnet brushless motor.

4. A bathing pool as claimed in claim 3, in which the permanent magnet brushless motor comprises a winding divided into a plurality of sections and switch means for selectively connecting the sections of the winding in one of a plurality of different configurations, wherein each section is connected in series and/or parallel with all other sections of the winding.

5. A bathing pool as claimed in claim 4, in which said switch is arranged to change the configuration of the coil segments in series, parallel or a combination of both, which are connected to the supply.

6. A bathing pool as claimed in any preceding claim, in which the control unit is further arranged, in a fourth mode, to selectively operate the pump motor at a yet higher speed of say 275 litres a minute, in order to pump water even more vigorously through the water jet for a limited duration.

7. A bathing pool as claimed in any preceding claim, in which the control unit is arranged to activate the pump motor in said second mode at least once during a 24 hour period.

8. A bathing pool as claimed in claim 7, in which the period of activation in said second mode has a minimum duration of 1 hour.

9. A bathing pool as claimed in any preceding claim, in which the control unit comprises an actuator for stopping the pump motor in the event of an emergency or other situation.

10. A bathing pool as claimed in claim 9, in which the control unit is arranged to restart the motor in at least said first mode, once a predetermined period has elapsed following actuation of the actuator.

11. A bathing pool as claimed in claim 10, in which means are provided for indicating that the motor is about to restart.

12. A bathing pool as claimed in claim 11, in which said indicator means is in the form of a countdown timer.

13. A bathing pool as claimed in any preceding claim, in which the control unit comprises an actuator for selecting the third mode of pump motor operation.

14. A bathing pool as claimed in claim 6 or claim 13 as appended to claim 6, in which the control unit comprises an actuator for selecting the fourth mode of pump motor operation.

15. A bathing pool as claimed in claim 14, in which the control unit comprises a memory enabling the third and/or fourth modes of pump motor operation to be programmed.

16. A bathing pool as claimed in any preceding claim, in which the control unit comprises a display screen, which can show the mode of operation and/or a menu enabling parameters of operation, such as timing to be programmed or selected.

17. A bathing pool as claimed in claim 16, in which the screen can also be programmed to display operational, technical or other messages such as advertisements.

18. A bathing pool as claimed in claim 16, in which the display screen is able is arranged to display the mode of operation and/or the menu in a range of selectable languages.

19. A bathing pool as claimed in any preceding claim, in which the control unit comprises means for connecting it to a remote station, so that it can be programmed remotely and/or so that remote fault diagnosis and maintenance can be carried out.

20. A bathing pool as claimed in claim 19, in which the connection means comprises a wired or wireless link, for example using a telephone line, cable or GPRS.

21. A bathing pool as claimed in any preceding claim, in which the control unit comprises a terminal for connecting it to a computer for local fault diagnosis or maintenance.

22. A bathing pool as claimed in any preceding claim, in which the control unit comprises means for fault diagnosis of the pool.

23. A bathing pool as claimed in any preceding claim, in which the control unit is arranged to prompt the user to actuate a particular actuator, the unit being able to determine whether the actuator has been actuated.

24. A bathing pool as claimed in any preceding claim, in which the pool comprises an audio output device such as a loudspeaker, the control unit being arranged to drive the device to play warning and/or advertising messages.

25. A bathing pool as claimed in any preceding claim, in which a heater is connected in series with the duct, the heater comprising one or more magnets for conditioning the water to prevent the accumulation of lime scale on the heating element or matrix.

26. A bathing pool substantially as herein described with reference to the accompanying drawings.