IE20060518A1 - A domestic water supply system - Google Patents

Abstract

A domestic water supply system (1) includes a cold water storage tank (2) and hot water storage tank (3) with means (40) for heating water in the hot water storage tank (3). A cold water discharge pump (5) mounted in the cold water storage tank (2) is operable to deliver cold water from the cold water storage tank (2) through a transfer pipe (6) into the hot water storage tank (3) for displacement of hot water from the hot water storage tank (3) on demand through an outlet (8) at a top of the hot water storage tank (3) for delivery through a hot water supply system feeding sinks, baths, showers and the like. <Figure 1>

Description

This invention relates to domestic water supply systems and in particular to the supply of hot water to sinks, baths, showers and the like in a building.

The term domestic water supply system as used in this specification is taken to include not only a household water supply system, but also water supply systems used in apartments, hotels, office blocks, public sport facilities and the like.

One typical known water supply system includes a cold water storage tank and an associated hot water storage tank. The cold water storage tank is connected to a mains water supply. A water transfer pipe delivers cold water under gravity from the cold water storage tank to the hot water storage tank. A cold water pump delivers cold water from the cold water storage tank to a cold water supply system connected to sinks, baths, showers and the like. Similarly, a hot water pump delivers hot water from hot water storage tank to a hot water supply system connected to the sinks, baths, showers and the like.

Problems can arise particularly in areas where there is a hard water supply. When the water is heated above 50°C lime settles out of the water and will coat an interior of the hot water storage tank, pipework and the hot water pump. Pump efficiency will gradually decrease and in time the pump will fail.

A further difficulty arises in areas where space for mounting the water tanks is limited, for example in apartment buildings and the like, in accommodating the bulk of the water discharge pumps mounted adjacent to the storage tank outlets for discharging water from the storage tanks. The pumps are typically floor mounted beside the 0 water storage tanks and thus may be exposed to accidental damage. Further, a leaking pump can cause damage to the surrounding building structure.

The present invention is directed towards overcoming these problems.

IE 060 5 Statements of Invention According to the invention there is provided a domestic water supply system including: a cold water storage tank having an inlet for connection to a water supply and an outlet, a hot water storage tank having heating means for heating water stored in the hot water storage tank, the hot water storage tank having a cold water inlet and a hot water outlet, said cold water inlet being connected to the outlet of the cold water tank by a cold water transfer pipe, said hot water outlet for connection to a hot water supply system, wherein means is provided for delivering cold water from the cold water storage tank to the hot water storage tank for forced discharge or displacement of water from the hot water storage tank on demand to the hot water supply system.

In one embodiment of the invention a cold water discharge pump is provided for discharging cold water from the cold storage tank into the hot water storage tank for discharging water from the hot water storage tank.

Preferably the cold water discharge pump is mounted within the cold water storage tank.

In a particularly preferred embodiment the cold water discharge pump is a submersible pump mounted within the cold water storage tank. ΙΕ ο 6 0 5 1 8 - 3 In another embodiment the submersible pump is mounted at the bottom of the cold water storage tank.

In a further embodiment the submersible pump is supported on a associated tray at the bottom of the cold water storage tank.

In another embodiment the cold water storage tank is mounted directly above the hot water storage tank, said tanks forming a combination unit.

In another embodiment the hot water storage tank heating means is a heating coil mounted within the hot water storage tank and having an inlet and an outlet for connection to a heating system for circulation of hot water through the coil to heat the water in the hot water storage tank.

In a further embodiment the hot water storage tank heating means is an electrical immersion heater mounted on the hot water storage tank for heating water in the hot water storage tank.

In some cases both heating coil and an electrical immersion heater will be provided on the hot water storage tank.

In another embodiment a ballcock and float is mounted at the inlet of the cold water storage tank for controlling supply of water into the cold water storage tank.

In a further embodiment a pressure reducing valve is mounted in the cold water transfer pipe for regulating water pressure.

In another embodiment an expansion vessel is connected to the cold water transfer pipe to accommodate expansion of water heated in the hot water storage tank.

In another embodiment an expansion relief valve is mounted on or connected to the cold water transfer pipe to discharge expanded water to a drain if the expansion vessel fails.

IE 0 6 0 5 1 8 - 4 In another embodiment each of the cold water storage tank and the hot water storage tank are enclosed within a layer of rigid insulating foam retaining within an outer metal casing.

In another aspect the invention provides a method for supplying hot water in a domestic hot water supply system including heating water in a hot water storage tank and delivering hot water to the hot water supply system by forcing the hot water from the hot water storage tank by supplying pressurised cold water into the hot water storage tank to displace the hot water from the hot water storage tank.

Detailed Description of the Invention The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which; Fig. 1 is a schematic sectional elevational view of a domestic water supply system according to the invention; Fig. 2 is a plan view of the system shown in Fig. 1; Fig. 3 is an elevational view of a tray forming portion of the apparatus used in the system; Fig. 4 is a partially cut-away elevational view of a hot and cold water supply unit forming part of the system; Fig. 5 is a schematic perspective view of the hot and cold water supply unit; and Fig. 6 is a view similar to Fig. 5 showing another hot and cold water supply unit.

Referring to the drawings, there is illustrated a domestic water supply system - 5 IE 0 6 0 5 ΐβ according to the invention indicated by the reference numeral 1. The system 1 includes a cold water storage tank 2 mounted directly above a hot water storage tank 3. Both tanks 2, 3 together form a combination unit. A submersible pump 5 is mounted within the cold water storage tank 2 for delivery of cold water from the cold water storage tank 2 through a transfer pipe 6 into the hot water storage tank 3. As the pump 5 delivers cold water through the transfer pipe 6 into a bottom of the hot water storage tank 3 hot water is discharged through an outlet 8 at a top of the hot water storage tank 3 for delivery through a hot water supply system feeding sinks, baths, showers and the like.

The cold water storage tank 2 is a cylindrical copper tank. The tank 2 has a circular base 10 which curves upwardly towards a periphery of the base 10. A cylindrical side wall 11 extends upwardly from a periphery of the base 10. A close-fitting circular lid 12 engages with an upper rim 13 of the side wall 11 to close the tank 2. A screened air inlet 14 is provided on the lid 12. A water mains inlet 15 for connection to a mains water supply is provided at a top of the cold water storage tank 2. Mounted at the mains inlet 15 is a ballcock and float assembly 16 for controlling the supply of cold mains water into the cold water storage tank 2. Means 18 for connection to an overflow warning pipe 19 (Figs. 5 and 6) is also provided at a top of the cold water storage tank 2.

The submersible pump 5 is mounted on a flat bottomed tray 20 at a bottom of the cold water storage tank 2. This tray 20 is shown in more detail in Fig. 3 and has a flat base 21 with an upwardly and outwardly extending side wall 22 terminating in an upstanding rim 23 which is perpendicular to the base 21. The outside diameter of the rim 23 corresponds to the inside diameter of the cold water storage tank 2 such that this rim 23 slidably engages against an inside face of the inside wall 11 of the cold water storage tank 2. An inlet pipe 24 is connected to an inlet of the pump 5 to draw water from a bottom of the cold water storage tank 2. An outlet 27 of the pump 5 is connected to the cold water transfer pipe 6 which has an outlet 29 adjacent a bottom of the hot water storage tank 3. Pressure switches (not shown) are provided for operation of the pump 5. The pump 5 is provided with both dry run and thermal protection. - 6 ΙΕ θ 6 Ο 5 1 8 The cold water storage tank 2 is encased in an insulated jacket 30 and sits on a wooden insulation board 31 mounted between a bottom of the cold water storage tank 2 and a top of the hot water storage tank 3.

The hot water storage tank 3 is also generally cylindrical having an upstanding cylindrical side wall 35 closed at each end by a curved base 36 and a curved top 37. The hot water storage tank 3 is encased in an insulation jacket 38 and sits on a flat base wooden board 39.

A heating coil 40 is located within a bottom portion of the hot water storage tank 3 and has an inlet 41 and an outlet 42 extending through the side wall 35 of the hot water storage tank 3 for connection to a domestic central heating system for example. Thus domestic central heating water can be circulated through the coil 40 for heating water in the hot water storage tank 3. In addition, or as an alternative, an electrical immersion heater 45 may be provided on the hot water storage tank 3. Thermostats 47 are mounted on the hot water storage tank 3 for controlling heating of the water in the hot water storage tank 3. A hot water return connection 48 is provided in the side wall 35 for return of hot water from the hot water circulation system if desired.

A dual coil hot water storage tank can be provided for use with solar power or heat pump applications.

A tee-piece 50 mounted on the transfer pipe 6 within the cold water storage tank 2 has an associated take-off pipe 51 to supply cold water for balanced cold water services such as showers, baths, wash hand basins and the like.

In use, water is heated in the hot water storage tank 3 by means of the coil 40 and/or immersion heater 45. Hot water is discharged from a top of the hot water storage tank 3 through the outlet 8 for delivery to baths, showers and the like on demand. The hot water is forced out of the hot water storage tank 3 by pumping cold water from the cold water storage tank 2 by means of the pump 5 through the transfer pipe 6 into a bottom of the hot water storage tank 3, thus pushing the hot water out. - 7 If λ β 0 5 ,1 It will be appreciated that the system of the invention is very quiet as the submersible pump 5 is housed within the insulated cold water storage tank 2. Mounting the pump 5 within the cold water storage tank also provides a space saving and protects the pump 5 as it is fully enclosed within the cold water storage tank 2. Further, it will be noted that no hot water passes through the pump 5 so that the difficulties mentioned previously with passing hot hard water through a pump are avoided. Also as hot water does not travel through the pump the seals in the pump will last longer. Even if a pump were to leak there would not be any damage to the building structure as the leakage would be contained within the cold water storage tank. The system is also very compact and has a reduced footprint. External pipework to the pump is eliminated.

Fig. 4 shows the combination unit with a pre-painted steel sheet outer casing 60 which retains insulation 30, 38 comprising at least 50 mm of CFC-free rigid polyurethane foam about an exterior of the cold water storage tank 2 and hot water storage tank 3.

When an immersion heater 45 is provided this is controlled through a thermostat which senses the water temperature. A desired operating temperature can be preset by adjustment of the thermostat. As a further back-up to the thermostat there is a thermal cut-out incorporated which operates to cut out power supply to the immersion heater 45 in the event that the thermostat fails and the water temperature within the hot water storage tank 3 rises too high.

Similarly, where a heating coil 40 is provided a cut-out valve may be provided in the domestic central heating water supply line to cut out heating water supply in the event that the thermostat fails and the temperature rises too high in the hot water storage tank 3.

A temperature and pressure relief valve 62 at the top of the hot water storage tank 3 is a further safety device to back-up the thermostats and thermal cut-outs. The valve senses an excess in water temperature or pressure in which case hot water is dumped via line 61 into a discharge tundish 63 and hence to a drain 64.

IE 0 6 0 5 1 8 - 8 A cold water combination valve 65 is also provided. This includes a combined line strainer/pressure reducing valve and core non-return valve/expansion relief valve 66. The pressure reducer ensures the correct operation of an expansion vessel 67 and prevents any damage to control valves due to excessive pressure. The non-return valve ensures any water expansion is forced into the expansion vessel 67 and prevents contamination of the incoming cold water supply. The expansion relief valve 66 which is set at 6 bar will discharge expanded water through pipe 68 to the discharge tundish 63 if the expansion vessel 67 fails.

Cold water is delivered to a bottom of the hot water storage tank 3. When water in the hot water storage 3 is heated it expands. The expansion vessel 67 accommodates this increase in volume.

Fig. 5 shows an arrangement whereby the hot water storage tank 3 is heated by a heating coil 40 connected to a domestic central heating system with an optional electric immersion heater 45 back-up.

Fig. 6 shows a system which incorporates a pair of immersion heaters 45 for heating the water in the hot water storage tank 3. These immersion heaters 45 are controlled through a thermostat which senses the water temperature.

In the arrangements shown in Figs. 5 and 6 the transfer pipe 6 is brought out at a bottom of the cold water storage tank 2 for fitting of the cold water combination valve 65, expansion relief valve 66 and expansion vessel 67 before re-entering the hot water storage tank 3 for discharge of the incoming cold water at a bottom of the hot water storage tank 3 as previously described.

The pump 5 is preferably arranged as shown in the drawings or it could possibly have the controls and/or prime mover mounted externally of the cold water storage tank 2 on top of the tank for example, with the pump 5 itself within the cold water storage tank 2.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail within the scope of the appended claims.

Claims (11)

1. A domestic water supply system including: a cold water storage tank having an inlet for connection to a water supply and an outlet, a hot water storage tank having heating means for heating water stored in the hot water storage tank, the hot water storage tank having a cold water inlet and a hot water outlet, said cold water inlet being connected to the outlet of the cold water tank by a cold water transfer pipe, said hot water outlet for connection to a hot water supply system, a cold water discharge pump being provided for delivering cold water from the cold water storage tank to the hot water storage tank for forced discharge or displacement of hot water from the hot water storage tank on demand to the hot water supply system.

2. A domestic water supply system as claimed in claim 1, wherein the cold water discharge pump is mounted within the cold water storage tank.

3. A domestic water supply system as claimed in claim 1 or claim 2, wherein the cold water discharge pump is a submersible pump.

4. A domestic water supply system as claimed in claim 3, wherein the submersible pump is mounted at the bottom of the cold water storage tank.

5. A domestic water supply system as claimed in any of claims 2 to 4 wherein the pump is supported on an associated tray at the bottom of the cold water IE 0 6 0 5

6. A domestic water supply system as claimed in any preceding claim, wherein the cold water storage tank is mounted directly above the hot water storage tank, said tanks forming a combination unit.

7. A domestic water supply system as claimed in any preceding claim, wherein the hot water storage tank heating means is a heating coil mounted within the hot water storage tank and having an inlet and an outlet for connection to a heating system for circulation of hot water through the coil to heat the water in the hot water storage tank.

8. A domestic water supply system as claimed in any of claims 1 to 5 wherein the hot water storage tank heating means is an electrical immersion heater mounted on the hot water storage tank for heating water in the hot water storage tank.

9. A domestic water supply system as claimed in any preceding claim wherein a heating coil and an electrical immersion heater are provided on the hot water storage tank as the heating means.

10. A domestic water supply system as claimed in any preceding claim wherein a pressure reducing valve is mounted in the cold water transfer pipe for regulating water pressure. 11. A domestic water supply system as claimed in any preceding claim wherein an expansion vessel is connected to the cold water transfer pipe to accommodate expansion of water heated in the hot water storage tank. 12. A domestic water supply system as claimed in claim 10 wherein an expansion relief valve is mounted on or connected to the cold water transfer pipe to discharge expanded water to a drain if the expansion vessel fails. ΙΕ ο 6 Ο 5 1 8 - 10 storage tank.

11. - 11 13. A domestic water supply system as claimed in any preceding claim wherein each of the cold water storage tank and the hot water storage tank are enclosed within a layer of rigid insulating foam retaining within an outer metal casing. A domestic water supply system substantially as hereinbefore described with reference to the accompanying drawings.