GB2300467A - Water heating apparatus - Google Patents

Abstract

A unit for heating domestic hot water is supplied as a single piece of apparatus, and is ready for installation in for example a cupboard in a house. In the unit there is a boiler 14 for heating the water and at least one and preferably two water storage tanks 10, 12 which or each of which is of a tall slender shape and lies with its long dimension upright in use. The boiler is mounted above the top of the tank or tanks so that it will be close the roof space in the house whereby shorter lengths of intake and exhaust pipe are required for the boiler.

Description

Improvements Relating to Water Heating Apparatus This invention relates to water heating apparatus, and in particular concerns water heating apparatus usable mainly in connection with the heating of water for domestic dwellings.

As the explanation of the invention proceeds, it will be appreciated that the invention may be adapted for the heating of water in other buildings such as small offices and workshops, but as clearly the main application of the invention is for domestic water heating, references hereinafter will be limited to this application.

The methods of heating water in domestic dwellings have changed over the last fifteen years. Thus, prior to 1980 in the United Kingdom, water heating systems comprised a boiler and a water storage tank. The boiler served to heat the water in the storage tank by heat exchange, and the water in the tank could be drawn off at outlets such as taps in the dwelling for washing purposes. The water in the tank was referred to as secondary water, and was distinguished from what was referred to as the primary water which was contained in the central heating system connected directly to the boiler. Such systems are still in use today in the United Kingdom, but more and more domestic hot water systems are based upon what is known as thermalstorage.In thermalstorage systems, again a storage tank has water contained therein which is heated by the boiler, but the boiler operates to maintain the water in the tank at a preset level, for example in the order of 76 to 80"C and when there is a demand for heat or hot water, a draw is made on the store which may or may not result in the boiler being fired depending upon the demand. The boiler reacts in relation to the temperature of the store, in order to add heat to the store when required. This may take place at times when the demand has terminated, and the thermalstore therefore acts in a similar manner to the well-known electric thermalstorage heaters. Thermalstorage has been found to be a more economical system for the management and supply of hot water to a domestic dwelling.

As a development of thermalstorage there has been introduced what is known as "integrated thermalstorage" wherein the storage tank contains primary water which is circulated through the domestic dwelling central heating system and in addition the primary hot water is utilised by being passed through heat exchange means in order to heat mains pressure secondary water to meet the demand for hot water at the outlet taps.

As a competitor to thermalstorage systems there has been developed the "combi" boiler system which is basically a hot water boiler arranged to supply water at mains pressure directly to outlet taps, or to heat water in a central heating system connected to the boiler. With such a combi boiler system, there is no separate storage tank for water, the arrangement being that the boiler includes a burner heat exchanger through which the primary water for the central heating system is pumped in the event of a demand for space heating, or through which mains water is pumped in the event that there is a demand for hot water at the outlet taps.The system is prioritised insofar as if there is a demand for hot water at the taps, that demand takes priority over a demand for space heating which in practise does not create any problems because demands for hot water at taps are usually prevalent only for a relatively short time and the diversion of the heat from the heating system to the secondary hot water demand is unlikely to have any significant effect on the heating system.

The problem with combi boilers however is that they are limited in terms of providing sufficient quantities of hot secondary water for example when hot water is required for baths, because they cannot provide sufficient output flow rates at sufficiently high temperatures to achieve the running of a bath in a reasonable time.

To overcome this difficulty, combi boilers have more recently been combined with storage tanks to provide a volume of hot secondary water which can be drawn on demand, resulting in a unit which is a combi and also a thermal storage system. The combi boiler and the storage tank are located side by side and are housed in a casing which typically is fitted into the domestic dwelling kitchen under the sink and is a fairly large, cumbersome unit. The outlet flue from the boiler is invariably taken from the combi unit through the domestic dwelling wall so that the flue gases can be discharged into the atmosphere.

It has also been known to provide combined boiler/thermalstorage tank units for fitting in cupboards, so that small bore flue pipes connected to the boiler can be directed from the cupboards which may be centrally located in the dwelling, through the dwelling structure and out of the dwelling through the wall thereof. Such small bore arrangements require the use of a fan assisted flue in order to achieve sufficient discharge of the flue gases to the atmosphere outside the dwelling.

The disadvantage of using a flue fan is that it is noisy, and if it ends up being located adjacent bedrooms in the domestic dwelling, then it can disturb the occupant's sleep.

The present invention in a simple and effective manner provides an arrangement wherein considerable advantages can be achieved, and at least in the preferred form, some of the disadvantages mentioned above can be overcome.

Also in preferred forms, the unit can be adapted for use in domestic dwellings which are larger than those for which thermalstorage systems have heretofore been designed, as will be clear from the following.

In accordance with the present invention in the most general aspect thereof, a boiler/thermalstorage unit for heating domestic water comprises a boiler and a thermalstorage tank means arranged as a single unit and installed as such, wherein a boiler is located directly above the storage tank means.

This particular configuration, which is opposite to conventionally adopted configurations, wherein the boiler is located underneath the storage tank, provides a number of particular advantages depending upon the circumstances in which the unit is installed.

A main advantage is that the unit can be made tall and slender by comparison with for example the combined combi/storage tank unit discussed above, and it can be located in a cupboard in the centre of a domestic dwelling.

It should be mentioned that most new domestic dwellings built in the United Kingdom today do have a cupboard located approximately centrally of the house, and usually on a landing of a central staircase.

Such a cupboard invariably will be located at a level which is probably higher than ground level of the house, and as the boiler is positioned at the top of the unit, so it is therefore located near the roof space. Accordingly, the air intake for the boiler, if it is of such size that air cannot be drawn in from the surrounding atmosphere inside the house, can be from the roof space in the house, and the minimum length of intake piping will be required. Equally, the flue from the boiler will be closer to the roof, and therefore can be taken through the roof which is the most convenient position for a flue which is exhausting products of combustion.

The conventionally known combined boiler and thermalstorage units where the boiler is located under the thermalstorage tank have been relatively small e.g. of input in the order of 7 Kw and of output in the order of 5 Kw, and these units are permitted to draw combustion air for the boiler from the air surrounding the unit. When units of higher output are however required, the air for combustion must be drawn from the air outside the inhabited parts of the dwelling. Thus the air must be drawn from the roof space, or from outside the house. The invention therefore enhances the capability of the units which can be made for example of 10 and 15 Kw output, which is adequate for providing for the hot water requirements of the homes which are currently being built and which are invariably provided with at least two bathrooms.

An advantage of the arrangement furthermore is that in the majority of cases fan assisted discharge is not required, especially where the flue is allowed to extend directly from the boiler and through the roof to atmosphere.

There are considerable savings in air intake pipe costs and flue pipe costs with the arrangement according to the invention.

The storage tank means may comprise a pair of separate water storage tanks connected in parallel in order that the width of the unit can be kept to a minimum, and the boiler is preferably mounted directly above the storage tanks. The unit may have a casing of attractive design housing the boiler and storage tanks so that the unit will have an excellent aesthetic appearance.

The storage tanks preferably are of the sealed type, so that the conventional feed and expansion tank as used in domestic hot water systems can be eliminated, and where such a sealed system requires an expansion unit, that expansion unit preferably is located under the storage tanks.

The thermalstorage arrangement of the unit preferably is integrated thermalstorage, and the heat exchanger for the secondary hot water may be a plate heat exchanger located under the thermalstorage tanks.

A particularly compact and novel arrangement therefore results.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein: Fig. 1 shows diagrammatically the elements of the unit and the hydraulic connections between the boiler and the storage tank means; Fig. 2 shows the storage tank means and the hydraulic connections to the central heating system; Fig. 3 shows the storage tank means and the hydraulic connections for the heating of domestic hot water; and Fig. 4 shows the unit in perspective elevation and how the major components are located inside the casing.

Referring to the drawings, Figs. 1, 2 and 3 show respective hydraulic circuit couplings in relation to the storage tank means which in this example is made up of two storage tanks 10 and 12 which are of identical elongate configuration as shown. Two storage tanks are used, coupled in parallel, in order to enable the width of the final unit to be reduced compared to one in which a single tank is used. In the production unit, the hydraulic connections of Figs. 1, 2 and 3 will be embodied in the same apparatus, but three figures have been used to improve the clarity of the illustration.

Reverting to Fig. 1, the two elongate tanks 10 and 12 are disposed upright and side by side, and above the tank in accordance with the embodiment of the invention is a boiler 14. Under the tanks are a heat exchanger 16 and an expansion chamber 18. In Fig. 1 the expansion chamber is shown as being hydraulically connected at 20 to the tanks 10 and 12, so as to take up any expansion of the water in the tanks 10 and 12 as a result of heating same.

The heating of the water is achieved by pumping the water from the tanks 10 and 12 via a boiler pump 22 through circulation lines 24 and 26. The arrows 28 show the flow direction in this circulation circuit.

Coupling lines 30 and 32 couple the tanks 10 and 12 in parallel and the pump 22 draws water from the tanks 10 and 12 through line 26 and then through a heat exchanger 34 in boiler 14 and the water is heated by means of a burner 36 as it passes through the heat exchanger 34. Combustion air is drawn in through the inlet pipe 38 as indicated by arrow 40, and is discharged through the top of the boiler 14 through the discharge pipe 42 as indicated by arrow 44. It should be noted that the pipes 38 and 42 in this embodiment are disposed vertically so that combustion air is drawn downwardly into the boiler, and is discharged vertically upwards.

The heated water is delivered through line 24 and is charged into the bottom of the tanks 10 and 12 through the parallel branch 32 whereby the water in the tanks 10 and 12 is heated to a predetermined and thermostatically controlled degree.

Tank 12 is shown as being provided with a filling coupling 46, and the tanks 10 and 12 which are of the sealed variety are initially filled from the mains by means of a mains coupling 48 which is coupled to coupling 46 during the filling operation. When filling has been completed however, coupling 48 is removed as it is a regulation that sealed water tanks have to be uncoupled from the mains after filling.

The water in tanks 10 and 12 is primary water and is therefore used for the central heating system of the dwelling.

Fig. 2 shows the hydraulic arrangement for the supply of the central heating system. The tanks 10 and 12 are shown, and also shown are two further parallel coupling lines 50 and 52 which respectively connect to circulation lines 54 and 56 of the central heating system. The central heating pump 58 is provided in line 54. When the central heating system calls for heating either by a timer device or a thermostatic device or both, water is circulated from the tanks 10 and 12 by pump 58 through lines 54 and 56 and the central heating radiators as indicated by the arrows in Fig.

2.

The third hydraulic circuit is shown in Fig. 3, and again the tanks 10 and 12 are coupled by parallel lines 60 and 62 by means of which hot water is circulated through line 64 by means of pump 66 as indicated by the arrows. The water pumped by pump 66 is circulated through the heat exchanger 68 which is a high efficiency plate heat exchanger of which the other couplings are connected to a cold water mains inlet line 72, and a hot domestic secondary water outlet line 74 which supplies water to for example the domestic dwelling outlet such as taps 76. Line 72 contains a flow switch 78 which is operated when for example a tap 76 is opened demanding hot water. This causes the water to flow through the line 72, plate heat exchanger 68 and line 74 to tap 76, and the flow switch 78 is actuated.When this switch is actuated, pump 66 is actuated causing circulation of hot water through the heat exchanger 68 and heat exchange between the flowing secondary water and the circulating primary water so that the secondary water is heated before it reaches the taps 76. The flow of the secondary water through the heat exchanger is by virtue of mains pressure.

Fig. 4 shows the assembled unit 80 and the spacial layout of the major components. It will be seen that the tanks 10 and 12 are located upright and side by side, and vertically above the tanks 10 and 12 is the boiler 14 with the inlet duct 38 and the exhaust duct 42 extending through the top of the unit casing (illustrated by reference 82 and in chain dotted lines), whilst the heat exchanger 16 is below tank 10, and the expansion unit is located under the tank 12.

Fig. 4 does not show all of the piping hereinbefore described, but it is conveniently arranged to extend down the insides of the side walls of the casing 82 whereby the unit will have a particularly neat appearance.

The location of the boiler 14 above the tanks in a single unit as shown in Fig. 4 provides the considerable advantages hereinbefore referred to. It can be seen for example in Fig.

4 that if the unit is located centrally of a dwelling, and especially if it is located at a high level and towards or close to the roof or roof space, the roof space can be connected to intake pipe 38, and the exhaust duct 42 can pass directly to the roof or roof space and through the roof at the ridge or through the tiles. No flue pump is required, despite the fact that the unit may be relatively highly rated i.e. in the order of 10 to 15 Kw.

Claims (8)

1. A combined boiler and thermal storage unit for heating domestic water comprising a boiler and a thermal storage tank means arranged as a single unit and installed as such, wherein the boiler is located directly above the storage tank means.

2. A unit according to claim 1, wherein the storage tank means comprises a pair of separate water storage tanks connected in parallel in order that the width of the unit can be kept to a minimum, and the boiler is mounted directly above the storage tanks.

3. A unit according to claim 2, wherein the tanks are of the sealed type.

4. A unit according to claim 2, including a safety expansion device connected to the tanks and located thereunder.

5. A unit according to claim 5, wherein the heat exchanger is a plate heat exchanger.

6. A unit according the claim 5, wherein the heat exchanger is a plate heat exchanger.

7. Aunit according to claim 6, wherein theheat exchanger is located under the storage tanks.

8. A combined boiler and thermal storage unit, substantially as hereinberfore described with reference to the accompanying drawings.