GB2174483A - Water heating apparatus - Google Patents

Abstract

Water heating apparatus comprises a primary water tank 10 from which hot water is circulated through a domestic heating system. The water is heated by passing burner combustion gases through a heat exchange coil 35 of small bore pipeline. The burner gases are collected in a collector 28 having an outlet 33 leading to the heat exchange coil 35. The discharge pipe 37 from the coil in a small bore pipe having a fan 39 for draining the gases from the collector through the heat exchange coil 35 and the discharge pipe. The discharge pipe being small can be located easily out of sight inside the domestic dwelling and at a position outside the domestic dwelling where it is unobtrusive. <IMAGE>

Description

SPECIFICATION Improvements relating to water heating apparatus This invention relates to water heating apparatus, and in particular is concerned with water heating apparatus of a type referred to hereinafter and in the claims as water heating apparatus of the type set forth having a tank which acts as a thermalstore for a body of primary water which is or can be selectively circulated around a flow heating circuit, such as a small bore central heating system in a domestic dwelling.

There may be a secondry water circuit including a heat exchange coil which is inside the thermalstore tank. The secondry water passes through the coil and receives heat from the primary water, (heated in a fashion which is in accordance with the invention and to be explained), and the heated secondry water which issues from the coil is for consumption for example at domestic water taps, washing machines, or for general purposes. The secondry water may be supplied directly from the mains and may pass through the coil under high pressure, which could be mains pressure but is probably at a pressure slightly less than the mains pressure, an appropriate regulator being provided in the secondry water connection between the mains and the heat exchange coil.

Water heating apparatus of the type described above is known, but typically the means for heating the primary water comprises a heat source such as a boiler or solar heating means through which the primary water from the tank is circulated for the heating of same.

As will be appreciated, the water heating apparatus as described above is mainly for domestic use, and if a conventional boiler is used in conjunction therewith for the heating of the primary water, there are limitations as to where the apparatus can be located inside a domestic dwelling. Thus, the conventional boiler requires to have either an open flue passing up through the dwelling and out of a roof tile, or if the boiler is of the balanced flue type, the apparatus must be located adjacent an outside wall of the building in which must be formed a fresh air intake for the boiler and an exhaust gases outlet, and the intake and outlet are required to be covered by means of a cover plate of metal located exteriorly of the building wall.

Needless to say, balance flue type boilers are criticised because of giving rise to the presence of an unsightly cover plate on the exterior wall of the dwelling. The open flue type of boiler can of course be located only in suitable locations inside the domestic dwelling.

In accordance with the present invention, it is proposed to heat the primary water in the tank by means of a novel heating arrangement, and in accordance with the present invention the heating apparatus is associated with a burner unit having a collector for the combustion gases, said collector unit leading the gases to a heat exchange coil located inside the tank and surrounded by the primary water, and further including fan means for driving or pulling the hot exhaust gases through the said heat exchanger coil, and further including a small bore discharge pipe which is for leading the gases away from the small bore heat exchanger coil to a location outside the domestic dwelling.

It will be appreciated that the small bore discharge pipe can be taken along any suitable route in travelling from the small bore heat exchange coil to a location outside the domestic dwelling.

For example the small bore pipe may run under the floorboards or in cavities in the walls of the domestic dwelling.

The heat exchange coil may also conveniently be a small bore pipe.

The burner unit is preferably mounted on the side of the tank so as to be detachable therefrom for replacement or repair, and the fan means circulating the combustion gases through the small bore heat exchange coil may comprise a small toroidal fan located in the discharge pipe. The outlet from the discharge pipe will be insignificant as regards impairing the exterior aspect of the domestic dwelling because of the smallness of the discharge pipe.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein: Figure 'is a diagrammatic, sectional side elevation of heating apparatus according to one embodiment of the present invention; and Figure 2 is a diagrammatic, sectional side elevation of part of heating apparatus according to a second embodiment of the invention.

Referring to the drawings, in Figure 1 is shown a tank 10 which comprises an inner casing 12 of copper or the like material, cladding insulation 14, and an outer case 16 of galvanised steel.

The tank defines two cavities namely a main cavity 18 and an expansion overflow cavity 20. The cavity 18 contains primary water which is circulated around a flow heating circuit through go and return pipes 22, 24, the direction of flow being indicated by arrows 26.

Cold water is supplied to the cavity 20 through pipe 32 and flow control valve 34, and flows from the cavity 20 into cavity 18 through downpipe 35.

Reference 36 illustrates an overflow in cavity 20 whilst expansion pipe 38 enables water to flow from the cavity 18 into the cavity 20 when the water in cavity 18 expands. The reference numeral 40 indicates a pump for circulating the hot primary water around the heating system 22 and 24. There is a bleed pipe 42 from pipe 24 to bleed a variable amount of the returning cooler water in pipe 24 through a controllable mixing valve 44 back into the line 22 whereby the temperature of the water flowing along pipe 22 can be controlled.

In the cavity 18 is a heat exchange coil 46, and this coil is immersed in the primary water in cavity 18 and is in two groups of coils 46A and 46B which although both are shown towards the bottom of cavity 18, in fact coil 46 only is towards the bottom of the cavity and the coil 46B is towards the top of the cavity 18 for the reasons explained in our co pending patent application No. 8502666.

The secondary water is inputted into the lower group of coils 46A through an inlet pipe 50, which may be supplied direct to the mains through suitable pressure reduction and non-return valves in order to ensure that the secondary water will be at the correct pressure, and that it will not flow back into the mains supply, which could cause contamination. The output pipe 48 is directed to consumer points in the domestic dwelling, such as hot water taps and/or a washing machine supply.The secondary water is heated in passing through two coils 46A and 46B, but the secondary circuit also has a bleed pipe 52 which has a one-way valve 54 leading to a control valve 56 by which a controlled variable amount of cold water bled from the line 50 is mixed with hot water issuing from the group of coils 46B to control the temperature of the hot water which is eventually discharged from the domestic taps.

The means for heating the primary water in accordance with the present embodiment of the invention comprises a burner unit 28 in which is contained a burner 29 comprising gas flames 30.

The bottom of the burner chamber 28 is open so that fresh air will be drawn thereinto as indicated -by arrow 31, and the combustion gases are collected at the top of chamber 28 and are led to a small bore pipe 33. The small bore pipe 33 couples with the small bore heat exchange pipe 35 inside the cavity 18, and the outlet from the small bore heat exchange pipe 35 leads to a small bore through the wall or roof 41 of the domestic dwelling so that the exhaust gases, after having the heat removed therefrom in passing through the pipe 35, are discharged to atmosphere.

The burner unit 28 preferably is detachable from the pipe 35 as is the discharge pipe 37, thereby to facilitate replacement and/or repair of the pipe 35.

Figure 2 shows an alternative arrangement wherein the burner 29 is located at or in the base of the unit 10, the base having the collector 45 for the combustion gases. Air is drawn into the space above the burner and into collector 45, and the products of combination are circulated through the heat exchange pipe 35 which is a small bore pipe.

The pipe 37 and fan 39 are as previously described.

The main advantage of using small bore piping for the heat exchanger and passing the exhaust gases therethrough using said toroidal fan which pulls the gases through the heat exchange pipe 35 at high velocity, is that the discharge pipe 37 can easily be concealed in a domestic dwelling, and the small bore outlet 41 can be made unobtrusive on the exterior of the domestic dwelling. By usisng a small bore discharge pipe 37, the installer has considerable flexibility in the positioning of the heating apparatus 10, in that it can virtually be placed anywhere in the dwelling.

The arrangement of Figure 2 may provide a neater unit in that the burner can be concealed, but the unit of Figure 2 does have the shortcoming that if the burner collector 45 fails, it may be nec essary to replace the entire unit 10.

The toroidal fan 39 can be arranged to blow the exhaust gases through the pipe 35 or as described to pull the gases-through such pipe. The coil 35 in the Figure 1 embodiment may be adapted to be removed as a unit through an aperture in the side wall of the tank 10 which is normally closed by means of a cap or plate to which the coil 35 is attached.

The apparatus according to the invention has a number of advantages including that the unit is capable of gravity circulation of the primary water.

The unit can be operated to condensing efficiency, which means that more than 80% of the useful heat can be extracted from the exhaust gases as they pass through the heat exchange coil 35. Any condensate in the coil 35 can readily be removed or discharged through the discharge pipe, which may be a relatively inexpensive plastics material pipe which will not rust.

The small bore piping referred to herein may be of any appropriate size considered to be a small bore, but typically the pipe size may be of the order of 22 to 28 mm in diameter.

In modified arrangements of the embodiments described, the outlet of the burner takes the hot gases to the top connection of the coil 35 and the pipe 37 is connected to the iower connection of coil 35 i.e. reversed to that shown. This arrangement facilitates the draining away of any condensate which collects in the tubing 35/37 and prevents it from running back into the burner.

Also, the positions of the coils 35 and 46 may be reversed compared to that shown in Figure 1.

Thus, the coil 46 would be located above the coil 35. Indeed, it may be possible to position the coil 35 between the two coil valves 46A, 46B.

Claims (7)

1. Water heating apparatus of the type set forth including a burner unit having a collector for the combustion gases, said collector unit leading the gases to a heat exchange coil located inside the tank and surrounded by the primary water, and further including fan means for driving or pulling the hot exhaust gases through the said heat exchanger coil, and further including a small bore discharge pipe which is for leading the gases away from the small bore heat exchanger coil to a location outside the domestic dwelling.

2. Apparatus according to claim 1, wherein the burner unit is detachable therefrom for replacement or repair.

3. Apparatus according to claim 1 or 2, wherein the fan means circulating the combustion gases through the small bore heat exchange coil.

4. Apparatus according to any of Claims 1 to 3, wherein the burner comprises a gas burner above which is the collector for collecting the combustion gases and induced air which are passed through the small bore pipe by means of the fan.

5. Apparatus according to claim 1 or 2, wherein the burner collector is formed in the base of the tank containing the primary water.

6. Water heating apparatus substantially as her einbefore described with reference to the accompanying drawings.

Amendments to the claims have been filed, and have the following effect: (a) Claims 1, 3 and 6 above have been deleted or textually amended.

(b) New or textually amended claims have been filed as follows:

1. In a domestic dwelling, water heating apparatus of the type set forth including a burner unit having a collector for the combustion gases, said collector unit leading the gases to a gas heating coil located inside the tank and surrounded by the primary water, and further including fan means for driving or pulling the hot exhaust gases through the said heat exchanger coil, and further including a small bore discharge pipe which leads the gases away from the gas heating coil to a location outside the domestic dwelling.

3. Apparatus according to Claim 1 or 2, wherein the fan means circulating the combustion gases through the small bore heat exchange coil is a toroidal fan.

6. Apparatus according to any preceding claim, wherein the gas heating coil is of small bore pipe.

7. In a domestic dwelling, water heating apparatus substantially as hereinbefore described with referenced to the accompanying drawings.