GB2203525A

GB2203525A - Hot water storage tanks

Info

Publication number: GB2203525A
Application number: GB08807910A
Authority: GB
Inventors: Kenneth Frank Caulfield
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-04-07
Filing date: 1988-04-05
Publication date: 1988-10-19
Anticipated expiration: 2008-04-05
Also published as: GB8708264D0; GB8807910D0; GB2203525B

Abstract

A heating system utilises an unvented hot water storage unit 15. The storage unit is in the form of a vessel which is divided into two regions 18, 19 one having a heat exchange unit 20 of relatively high efficiency to give a high rate of heat exchange between heating fluid from a heat source 10 and water in the region. The other region 19 has a heat exchange arrangement 24 of relatively low efficiency. The invention has particular application in using boilers remote from the heat exchanger when rapid hot water requirements are to be met without requiring a large hot water storage capacity. <IMAGE>

Description

Heating System This invention relates to heating systems and in particular to heating systems in which an unvented hot water storage unit is included.

An object of the invention is to provide an improved heating system in which the benefits of an unvented hot water storage unit are utilised.

According to the invention a heating system comprises a heating fluid source and heat exchange means in communication ath the heating fluid source, the heat exchange means including a vessel constituting an unvented hot water storage unit and being divided internally into at least two regions, a first region having a heat exchange arrangement of relatively high efficiency giving relatively rapid heat exchange rate between the heating fluid and water in said first region, and a second region having a heat exchange arrangement of relatively low efficiency giving relatively slov heat exchange rate between the heating fluid and water in said second region whereby water in said regions is heated at different rates substantially independent of one another.

Preferably the flow of heating fluid is controlled to pass to the vessel either into the first region only or into both the first and second regions.

Conveniently the water to be heated in the vessel is passed to the second region and at least some of that water is then passed to the first region.

The first region is preferably substantially enclosed b the second region and constitutes a second vessel within the first-mentioned vessel.

The heated water from the first and second regions may be available for use at separate heated water outlets at different temperatures and in the case of the heated water from the first region, the water may be mixed with cold water to give water at a predetermined temperature.

In one arrangement the heating fluid is directed by valve means by which the heating fluid is passed to the first region only, to the first and second regions, or to the first region and to a space heating sstem. Such valve means may bela four way valve which is controlled by a motor, the motor being actuated by control means to give the desired flow from the source of heating fluid.

It will be appreciated that the heating fluid is returned to the source of such fluid after passing through the vessel and1 or the space heating means.

Further features of the invention will appear from the following description of embodiments of the invention given by way of example only and with reference to the drawings, in which: Fig. 1 is a schematic drawing of a heating system, Fig. 2 is a schematic sectional view of a four way valve for the system of Fig. 1, and Fig. 3 is a schematic vie of an alternative form of vessel for the system of Fig. 1.

Referring to the drawings and firstly to Figs. 1 and 2 a heating system includes a source 10 of heating fluid which may be a conventional boiler using conventional fuel and heating water for use as the heating fluid.

Fluid from the boiler 10 is circulated by a pump 11 to a four-way motorised valve 12. The valve 12 can pass the fluid to a conventional space heating arrangement 13, for example sets of radiators. The fluid from the radiators is returned to the boiler source 10.

Fluid may also be passed by the valve 12 to a vessel 15 which acts as an unvented hot water storage unit. The vessel 15 is substantially closed having a vacuum release and thermal relief valve 16 whereby a vacuum generated in the vessel 15 can be released and any excess temperature in the water results in water being drained off the vessel.

The vessel 15 is formed with two regions, a first inner region defined by an internal cylindrical vessel 18 located towards the upper end of the vessel 15 and fixed thereto. A second region 19 is defined b the remainder of the interior of the vessel 15.

The valve 12 permits flow of heating fluid to the heat exchanger either to the internal vessel 18 only, or to the vessel 18 and to the region 19 of the vessel 15 as will be described with reference to Fig. 2. Flow of heating fluid to the internal vessel 18 is to a heat exchange unit 20 within the vessel, the unit 20 only being shown schematically in Fig. 1.

Conveniently the unit 20 comprises outer and inner heat exchange coils (not shown), the fluid passing through the coils in series and the water to be heated being located in the vessel 18 in heat exchange relationship with the coils. The vessel 18 may be divided into sections one of which contains one coil and another the other coil so that in progressing through the vessel the water to be heated passes in a tortuous path over the coils. However other high capacity heat exchange means can be employed.

In each case the heat exchange arrangement is such that the heat exchange coefficient is relatively high and a high rate of heating of the water can be achieved. After passing through the coils the heating fluid passes out of the vessel through an outlet 21 into the region 19 through a pipe 22.

The valve 12 can also pass heating fluid to the region 19 through a pipe 23 leading to a heat exchange arrangement 24 in the region 19, in this case a helical coil having spaced apart turns of increasing diameter towards the base of the region 19. The pipe 22 joins with the outlet for fluid from the arrangement 24 before the fluid from both regions 18 and 19 is led out the vessel 15 and back to the boiler 10. The heat exchange arrangement 24 has a relatively low heat exchange efficiency and produces a relatively low rate of transfer of heat to water in the region 19 compared with the rate of transfer of heat in the unit 20.

Water to be heated in the vessel 15 is supplied from the mains water supply 30 through a non-return valve 31 and a pressure reducing valve 32 to a water inlet 33 into the base of the vessel 15. A water spreader 34 spreads the cold inlet water laterally in the base of the vessel 15.

An expansion vessel 35 is in communication with the water inlet 33 for safety reasons. The pressure reduced cold water supply is also connected to a mixing valve 37 to be described.

The water to be heated is located in the region 19 of the vessel 15 and, when the heat exchange arrangement 24 is operative, this water is heated. Some heat also passes to the region 19 from the vessel 18, when heated. Water is passed from the region 19 into the vessel 18 from the upper and a lower part of the region 19 b pipes 38 and 39 respectively which are joined to a pipe 40 leading into the vessel 18. A mixer 41 is located in the pipe 40 to ensure adequate mixing of the water which will be warmer in the upper part than in the lower part of the region 19.

Water heated in the vessel 18 leaves the vessel through a pipe 42 which passes out of the vessel 15 to the mixing valve 37. The mixing valve 37 is for enabling the hot water supply temperature to be at predetermined level independent of the temperature of the water leaving the vessel 18. Thus the mixing valve 37 mixes the supply of cold water with the supply of hot water to give the desired water output temperature. A temperature detector 43 downstream of the valve 37 monitors the water temperature and provides a signal to the motor controlling the setting of the valve 37 to bring about the predetermined temperature setting which can be adjusted to individual requirements. It will be noted that the cold water supply pressure matches the hot water supply pressure and a cold water supply (not shown) at the same controlled pressure is also available for other mixing purposes, for example for showers, if desired.

Hot water from the region 19 leaves the vessel 15 through a pipe 44 at the upper end of the region 19 and is separately available to supply hot water requirements.

It is envisaged that the hot water supply from the vessel 18 be available for more limited volume requirements such as at wash basins and showers, and as the heat exchange efficiency is such that the heating of this water is quick in vessel 18 the water can be heated on a demand basis.

The hot water supply from the region 19 is for larger volume requirements, the amount of water heated being relatively larger. Thus the hot water in the region 19 may be for peak demand periods and/or when, for example, water for bathing is required.

To determine when the hot water in the vessel 18 and in the region 19 is to be heated the motorised four-way valve 12 is provided. This valve has the function of passing heating fluid from the boiler 10 to one or more of the three heating fluid outlets, i.e. for space heating, fluid to the vessel 18 and fluid to the region 19.

Referring to Fig. 2 the three outlets are shown as a space heating outlet at 45, an outlet to vessel 18 at 46, and an outlet to region 19 at 47. The heating fluid inlet is at 48. The valve 12 has a shoe 49 of an outer arcuate shape in which there is formed two bores 50 and 51. The shoe is located in a cylindrical housing 52 at the junction of the inlet 48 and outlets 45, 46 and 47 and rotation of the shoe 49 about the central axis 53 of the housing 52 enables the valve to supply the heating fluid in the desired manner. In the illustrated valve the heating fluid can be supplied to the space heating outlet 45 and to the outlet 46 simultaneously or (as shown) to the outlets 46 and 47 but not to the outlet 45, but it will be appreciated that other arrangements are possible.

It is preferred that the valve be controlled by a motor which rotates the shoe 49 according to a preprogrammed arrangement which is adjustable according to the systems needs at any particular time.

In order to comply with the need for the water temperature in the region 19 not to exceed a certain high value a temperature detector 54 is mounted on the vessel 15 and controls the flow of heating water through the vessel by a valve 55.

As an alternative to the arrangement shown in Fig. 1 the vessel 15 may include two internal vessels 18 and 18A (Fig. 3) and associated heat exchange arrangements 20 and 20A both as shown and described in relation to Fig. 1, one 18 of which is at the upper end of the vessel 15 and the other 18A towards the lower end of the vessel 15.

In this case the supply of heating fluid is similar to that of Fig. 1 except that the heating fluid for the second lower vessel 18A would receive the heating fluid supply 23 previously used in the heat exchange arrangement 24.

Moreover the heated water output from the two internal vessels 18 and 18A provides a combined output of hot, relatively quickly heated water.

The water in the remaining part 19A of the vessel 15 which is equivalent to the region 19 is not normally directly heated by a heat exchange arrangement equivalent to 24 but is heated by heat exchange set up between the exterior of the heated internal vessels 18 and 18A. The heated water thus produced has a separate hot water outlet 44.

In other respects the arrangement of Fig. 3 is similar to that of Fig. 1 and the same reference numbers are used for equivalent parts.

It will be appreciated that by having two relatively high heat transfer rate regions in the vessels 18 and 18A a relatively greater quantity of water can be heated quickly.

At the same time a bulk hot water storage facility is also provided in the vessel 15.

It will also be appreciated that the heat exchanger vessel 15 is of particular application in the cases when a preexisting or otherwise separate boiler 10 is available as the source of heated water. The advantages of the heat exchange arrangement described can then be achieved without having to acquire a further boiler and/or without having to combine the heat exchanger function and the boiler function as a combined unit.

Moreover the system can be adapted in various ways according to the nature of the building or its function.

Thus, for example, a system may include two or more of the units 15 each being located according to the requirement for a quickly produced hot water supply and each supplied from the common boiler unit.

The illustrated arrangement can also be modified by, for example, arranging for feed of cold water to the vessel 15 for heating as soon as a water outlet, such as a tap, is opened. The cold water supplied to the vessel would then be quickly heated in the vessel and the heated water supplied to the outlet. This may be achieved by fitting a flow switch in the cold water supply pipe actuated by the opening of the outlet.

Operation of the flow switch may also actuate operation of the boiler and the valve 12.

As a further alternative the four-way valve 12 may be substituted by other valve arrangements. For example the space heating arrangement 13 may be supplied with heated water direct from the boiler 10 without it passing through the valve 12 in which case the valve 12 may be a three-way valve and the supply to the space heater 13 is controlled independently by a two-way valve, which may be motorised.

Claims

1. A heating system which comprises a heating fluid source and heat exchange means in communication with the heating fluid source, the heat exchange means including a vessel constituting an unvented hot water storage unit and being divided internally into at least two regions, a first region having a heat exchange arrangement of relatively high efficiency giving relatively rapid heat exchange rate between the heating fluid and water in said first region, and a second region having a heat exchange arrangement of relatively low efficiency giving relatively slow heat exchange rate between the heating fluid and water in said second region whereby water in said regions is heated at different rates substantially independent of one another

2.A system according to claim 1 wherein the flow of heating fluid is controlled to pass to the vessel either into the first region only or into both the first and second regions.

3. A system according to claim 1 or 2 wherein the water to be heated in the vessel is passed to the second region and at least some of that water is then passed to the first region.

4. A system according to claim 1, 2 or 3 wherein the first region is substantially enclosed by the second region and constitutes a second vessel within the first-mentioned vessel.

5. A system according to any one of the preceding claims wherein the heated water from the first and second regions is available for use at separate heated water outlets at different temperatures and in the case of the heated water from the first region, the water may be mixed with cold water to give water at a predetermined temperature.

6. A system according to any one of the preceding claims wherein the heating fluid is directed by valve means by which the heating fluid is passed to the first region only, to the first and second regions, or to the first region and to a space heating system.

7. A system according to claim 6 wherein the valve means is a four way valve which is controlled by a motor, the motor being actuated by control means to give the desired flow from the source of heating fluid.

8. A system according to any one of the preceding claims wherein the flow of water to the vessel is controllable by flow control means actuated by opening of an outlet for water from the vessel.

9. A heating system substantially as described with reference to Figs. 1 and 2 or Fig. 3 of the drawings.