GB2099557A - Demand type of water heater - Google Patents

Abstract

A water heater of the demand type having a water heating chamber which is permanently open to atmosphere via the outlet 35 and associated outlet pipes in use. A valve 33, 46 is embodied in the water heater for controlling the flow of water through the heating chamber and the valve is of a nature that it is controllable by manipulating a remote operating member 57 on the downstream side of the water heater. The operating member can be a pilot outlet for a diaphragm type of valve in which case a tube connects the valve with the operating member, or a mechanical linkage could be employed. In either case the tube or mechanical linkage are preferably located within the outlet pipe. A flow operated trigger means 43, 44 is embodied to activate the heating means when flow through the heater exceeds a predetermined value. <IMAGE>

Description

SPECIFICATION Demand type of water heater THIS INVENTION relates to a demand type of water heater, commonly known as "instant" water heaters, wherein water is heated to the desired temperature as it flows through the water heater with the heater being switched on as a result of the flow of water therethrough.

Many different forms of demand water heaters have been proposed and manufactured to operate, in some cases on an electrical supply, and in others on a gas supply.

In the case of simple demand heaters, with which this invention is, at least in part concerned, it is often required by law or local governing authorities that the interior of the water heater chamber or heat exchanger of the demand heater be open to atmosphere at all times. This is required in the absence of complex and rather costly safety switching arrangements or pressure relief arrangements being provided in the water heater.

It is often preferred to avoid the provision of such safety pressure relief or switching arrangements as a result of the fact that it increases the cost of the water heater substantially. It must be noted that usually the type of water heater with which the present invention is concerned, is directed at the lower income groups and therefore, it is desired to keep the costs down to a minimum. Accordingly, from practical considerations, the interior of the heating chamber must to all intents and purposes, be open to atmosphere at all times at least in the case of water heaters in a lower price range.

As a result of this practical requirement, all the demand heaters of this type which have been made available to the public, and of which applicant is aware, have been adapted for connection to the outlet side of a tap or other control valve to activate a switch to energise the electrically operated heating element or, alternatively, to open a control valve for the supply of gas to a burner arrangement in the case of a gas fired heater.

It will be understood that the location of such a water heater on the outlet side of a tap is, even in the application to a shower, not totally desirable as a result of the consequential displeasing appearance of the water heater and associated pipes and wires, and also the fact that it may be a nuisance, or even may become damaged as a result of its downstream location of a water heater requires that it is present within a bathroom, scullery or laundry and this may not be desired for many different reasons.

It is the object of this invention to provide a demand water heater of the type under consideration wherein the water heater is located upstream of operating means for controlling the flow of water through the water heater.

It will be understood that the terms "upstream" and "downstream" in relation to operating means for controlling the water heater mean on the inlet pressure and outlet pressure sides of the water heater respectively.

In accordance with this invention there is provided a demand water heater comprising a heater chamber having a water inlet and a water outlet associated therewith, means for heating water within the heating chamber, said means being adopted to be triggered to an operative condition by liquid flow through the heater and wherein the outlet from the heating chamber is permanently open in relation to the water outlet, from the heater, the water heater being characterised in that it embodies, between the inlet to the water heater assembly and the inlet to the heating chamber, a valve assembly which is operable by remote control relative to the water heater.

Further features of the invention provide for the valve assembly to be either a diaphragin operated valve wherein water pressure, in a chamber behind a diaphragm is adapted to control the flow of water through the diaphragm valve arrangement and wherein the pressure within said chamber can be regulated by a remote tap connected to said chamber by means of a suitable tube orforthe valve to be a simple wherein the closure chamber is limited to an operating member on the downstream side thereof; and for said suitable tube or linkage to be located within a water passage extending from the water heater to an outlet at a position removed therefrom.

Still further features of the invention provide for the said means for heating water to be either an electrical heating element or a gas burner arrangement; for there to be, in instances where the means for heating water is an electrical heating element, a flow operated electrical switch, preferably located on the inlet side of the heating chamber and adapted to operatively close a circuit to the electrical heating element when a flow of liquid above a predetemined minimum passes through the heater; for there to be, in the case of a geyser having a gas burner for heating the chamber, a flow operated diaphragm valve for controlling the supply of gas to the gas burner arrangement, and for the chamber to be arranged such that it remains substantially fuli of water even though it is open to atmosphere by way of an outlet pipe.

In a most preferred embodiment of the invention the water heating chamber is of a tubular configuration and has one or more electrical immersion heating elements passing substantially co-axially through the tubular chamber. The combination of the electrical heating element and chamber defining tube can be bent to a substantially coil form.

It must be noted, furthermore, that the term diaphragm valve is intended to include valves which have substantially planar diaphragms and also those which have tubular diaphragms. The latter will be more fully described hereinafter.

The invention also provides a water tap which provides for two flow paths therethrough, one of which is controllable by means of a closure member associated with the tap and the other of which is permanently open.

Further features of the latter aspect of the invention provide for the separate flow paths to be defined by the tap body itself in the one case and by a co-linear tube in the other case wherein one of the flow paths is controllable by a closure member.

It will be understood that whilst the above definition has been orientated primariiy around a remote control which is hydraulic in nature as a result of the separate tube and control of the flow of water there-through, it is weli within the scope of the present invention to provide a remote mechanical control which may, for example, be defined by an axially slideable flexible filament located within a suitable sheath therefor. In such a case, mechanical transmission of movement can take place by movement of the filament relative to the sheath and, in fact, the filament could be made sufficiently robust to accept compressive forces applied thereto in order to operate the valve within the water heater.

A particularly preferred form of the invention has, in fact, a mechanical linkage for operating the valve. In this case the outlet from the heating chamber is adapted for direct connection to a tap and the valve is in the form of a simple valve operable by the top spindle throug an extension rod. The rod passes through the normal valve seat with a clearance to ensure that the outlet from the heating chamber is always connected to atmosphere and the extension rod operates the valve located within the heater assembly.

Also, it is within the scope of the invention, that a low voltage electrically operated valve could be embodied within the water heater and such a valve could also be operable by a switch or like member at a position remote from the water heater.

In order to exemplify the invention, three different embodiments thereof will now be described.

In this description reference will be made to the accompanying drawings in which: Fig. 1 is a schematic elevation of a water heater adapted to be electrically operated; Fig. 2 is a similar illustration but of a water tap for use in combination with the water heater; Fig. 3 is a cross-section view of the valve arrangement along line Ill-Ill in Fig. 1; Fig. 4 is a section elevation of a water heater according to this invention; Fig. 5 is an end view thereof illustrating, in dotted lines, the flow paths within the water heater, and; Fig. 6 is a schematic elevation similar to Fig. 1 but of a gas fired water heater.

In the embodiment of the invention illustrated in Figures 1 to 3 an electric demand water heater of a small type (having a maximum through flow of about 10 litres per minute,) comprises a valve body 1 having a screw threaded socket inlet 2 for receiving an inlet pipe (not shown) in use, and a colinear and spaced spigot 4 for connection to a conventional outlet pipe (not shown).

The inlet 2 has associated therewith a flow operated switching arrangement including a plug 5 urged towards the inlet by a suitable spring 6 and acting to restrict the inlet passage 7. The plug comprises an elongated magnet encased in a protective, corrosion resistant sheath to prevent deterioration of the magnet. The arrangement is such that when flow takes place through the valve body and the magnet is urged by the flow of water to an inner position against the action of spring a reed switch 8 is closed by the magnet. Thus the reed switch will close when the force on the plug 5 exceeds a predetermined value which is chosen according to the minimum allowable flow rate of water through the heater. The reed switch operates a triac or other electronic switch for controlling electrical power to the heating element.

The inner end of the inlet communicates with a small bore passage 9 on a projection 10 arranged co-axially in the flow passage and which communicates with a transverse passage 11 in turn communicating with the interior of a diaphragm chamber formed by a tubular diaphragm 1 2 of elastomeric material carried on the projection. The diaphragm is adapted to cooperate with an inlet mouth 1 3 (see Fig. 3) associated with a passage 1 4 communicating with one end 1 5 of a tubular heating chamber 1 6 which is, in the operative position of the water heater, located below the outlet from the water heater.

A control outlet 1 7 from the diaphragm chamber 1 8 is adapted to be operatively connected to a tap assembly generally indicated by numeral 19 by means of a flexible small bore tube 20.

The diaphragm arrangement is such that the passage communicating with the heating chamber is closed when the pressure in the diaphragm chamber is equal to the inlet pressure. However, when the pressure in the diaphragm chamber is decreased as a result of allowing water to flow from the control outlet and through the small bore tube 20, then the mouth 1 3 is open and water flows into the heating chamber.

The heating chamber 1 6 is coiled together with an immersion heating element 21 therein and has an outlet 22 which communicates directly with the outlet 23 (see Fig. 3) from the valve body and thus with the interior of an outlet pipe in the operative condition.

The especially adapted tap 1 9 provided for use in controlling the flow through the control outlet and thus through the water heater comprises a body 24 of substantially conventional design in this particular instance. It must be understood that the present tap arrangement which is described as an example is adapted for conversion from a substantially standard tap and it must be appreciated by those skilled in the art that any suitable taps could be provided to substitute for the one described.

In this particular instance. the valve body is of substantially conventional design, as mentioned above, and has a valve seat 25 interposed between the inlet 26 and outlet spout 27 of the tap.

- In order to adapt the tap for use according to this invention, a fitting 28 is made so that it fits neatly into the valve seat but provides spaces indicated by numeral 29 around the periphery of the valve seat so that the inlet 26 to the tap body is always connected to the outlet 27 via the spaces 29. However, the fitting is adapted to be sealingly attached to the end of the small bore tube 20 and to provide a valve seat 30 cooperating with the usual tap washer 31 carried on the spindle 32 in conventional manner. Thus, the tap washer and spindle can be utilised to control the flow of fluid through the small bore tube alone whilst the outlet 27 from the heating chamber is always connected to atmosphere.

As a result of the construction of the tap as described, the flow of water through the small bore tube 20 can be stopped as and when required in which case, as mentioned above, the diaphragm valve will close This causes the reed switch to be opened as a result of the spring urging the magnet back to an inoperative position.

Thus, in turn electrical supply to the electrical heating element ceases as a result of the switch opening.

On the other hand when the tap is opened and therefore flow is allowed through the small bore tube 20 the diaphragm valve opens under the action of the water pressure and accordingly, water is allowed to flow through the passageway in the body and into the heating chamber. This causes the flow operated switch assembly to be closed and accordingly the electrical heating element to become heated.

It will be understood that by use of the above described water heater and tap arrangement, the water heater can be located out of sight and at a position remote from the final water outlet.

In the embodiment of the invention illustrated at Figures 4 and 5, the electric demand water heater comprises a valve body 33 screw-threaded spigot inlet 34 located co-axially with an outlet 35 conveniently defined by a Union nut 36 for connection to the lower end 37 of a pillar type of tap 38. The tap 38 can be located in the conventional aperture of a wash handbasin 39 to which it is secured by means of the usual nut 40 cooperating with the screw-threaded pillar 41.

The inlet 34 communicates with a passageway 42 in which is housed ferrite magnet 43. The ferrite magnet has two basic positions in operation, one in which it is remote from a magnetically operated switch 44 adapted to control the power supply to the heating elements of the water heater and a raised position in which it is adjacent the switch 44 and these by the flow of water through the passage. The magnetically operated switch is closed by the presence of the ferrite magnet in the latter position whilst being open in the former position.

The inlet passageway terminates in a transverse wall 45 having a central hole therethrough which defines, on the opposite side, a valve seat.

A closure member 46 co-operates with the valve seat and, in fact, has its out periphery 47 in sliding contact with the walls of the bore 48 in which it is located.

The outlet 49 from the valve (see Figure 5) is located on one side of the passage and communicates with the inlet to a heating tube 50 defining the heating chamber. A pair of parallel heating elements 51 pass axially through the tube 50 and are adapted to be energised when the magnetically operated switch is closed as a result of the proximity of the ferrite magnet. Any suitable switch gear can be employed to interface between the magnetically operated switch and the heating elements.

The outlet end 52 of the tube is open to the outlet from the water heater and thus communicates with the interior of the pillar of the tap and the outlet spout 53 thereof.

The closure member 46 is mounted at the inner end of an extended shaft 54 coupled at its upper end 55 to the conventional tap spindle 56 operable by means of a handie 57. The arrangement is such that the spindle can be rotated to move the closure member into firm contact with the valve seat thereby closing the inlet to the heating chamber. Rotation of the spindle in a direction corresponding to opening of the tap moves the extended shaft axially to open the valve and thereby enable water to flow through the inlet passage and into the inlet end of the tube defining the heating chamber. In so doing the ferrite magnet will be moved axially to a position in which the magnetically operated switch is closed and the heating elements are thus energised.It will be understood that the conventional tap washer and support therefor are removed from the tap to leave a permanently open passageway 58 communicating with the interior of the heating chamber by way of the outlet from the water heater.

It will be understood that numerous variations may be made to the above described embodiment of the invention without departing from the scope hereof. In particular the extended tap shaft could be replaced by a variety of different axially movable mechanical members as may be required. Also the means for moving the extending shaft axially could be varied as required and need not necessarily be a tap spindle. In fact any remote mechanical means could be employed for moving the extended shaft axially.

The invention may equally well be applied to a gas operated demand heater as illustrated in Figure 6 of the accompanying drawings. In such a case, the valve arrangement, generally indicated by the numeral 60 is controlled in a similar way and by a substantially identical tap arrangement.

Instead of a tubular diaphragm there is, in this case, a circular, planar diaphragm 61 co-operating with a seat 62 at the inner end of an inlet passage 63. The diaphragm chamber 64 is formed on the opposite side of the diaphragm and the small passage 65 passes through the diaphragm coaxially with the inlet. The outlet 66 is positioned radially outwardly of the inlet 63 so as to communicate therewith via the valve seat only. A small bore tube 67 connects with the diaphragm chamber as in the first described example.

However, in this case, the outlet from the valve arrangement is connected to a heat exchanger 68 which, in this case, defines the heating chamber.

The heat exchanger 68 is located above a gas burner assembly 69 and the end of the heat exchanger remote from the inlet has an upwardly directed inverted U-shaped portion 70 communicating with an outlet pipe 71 which turns the heated water from the heat exchanger to the usual water pipe 72 by way of the valve body.

The gas supply to the gas burner arrangement 69 is by way of a diaphragm valve 73 which, through a connecting rod 74, controls the gas supply from the gas inlet 75 to the burner heads.

The diaphragm valve is connected between a high pressure part of the pipe leading to the heat exchanger and a venturi 76 located in this pipe.

Thus, the diaphragm valve is operated by the difference in pressure created between the low pressure zone of the venturi and the relatively higher upstream pressure. Accordingly, the diaphragm valve is operated by this pressure difference which will be dependant upon the flow rate of water through the pipe.

It will be understood that in use the above described gas operated water heater may be controlled by controlling the remote tap which cooperates with the small bore pipe by means of which the main diaphragm controlled valve 31 is controlled.

When the tap is opened, as described above, the main valve opens and water is free to flow into the heat exchanger by way of the venturi. Flow through the venturi will cause the diaphragm valve to open the gas supply to the burner heads which, in the usual manner, become ignited as a result of the presence of a constantly burning pilot light (not shown).

Water flowing into the heat exchanger leaves the heat exchanger via the inverted U-shaped section of the pipe which, when the tap is closed and the main valve then closes, ensures that the heat exchanger portion of the heater remains full of water and that only the water in the outlet pipe can drain away through the tap.

Heated water therefore is available at the outlet tap in a manner substantially as described above with regard to the electrically operated water heaters.

There are numerous modifications and variations which may be made to the above described embodiments of the invention without departing from the scope hereof. In particular, the modification and construction of the tap may be varied widely even for the hydraulic remote control of the present embodiment of the invention. In addition to this, as already stated, mechanical and electric remote control means may be provided in order to operate a valve located within the electrical heater.

The invention therefore provides a usefui and simple arrangement which will enable the advantageous location of water heaters of the type described to be achieved whilst allowing the interior of the heating chamberto be open to atmosphere through the outlet pipe associated with the heater.

Claims (11)

1. A demand water heater comprising a heating chamber having a water inlet and a water outlet associated therewith, means for heating water within the heating chamber, said means being adapted to be triggered to an operative condition by liquid flow through the heater and wherein the outlet from the heating chamber is permanently open in relation ot the water outlet from the heater, the water heater being characterised in that is embodies, between the inlet to the water heater assembly and the inlet to the heating chamber, a valve assembly which is operable by remote control relative to the water heater.

2. A demand water heater as claimed in claim 1 in which the valve assembly is a diaphragm operated valve wherein water pressure in a chamber behind a diaphragm is adapted to control the flow of water through the diaphragm valve arrangement and wherein the pressure within said chamber can be regulated by a remote tap connected to said chamber by means of a suitable tube orforthe valve to be a simple valve where the closure member is limited to an opening member on the downstream side thereof.

3. A demand water heater as claimed in claim 2 in which the remote tap has an annuiar passage therein constantly connected to the heating chamber and a central valve seat and closure member therefor for controlling flow through said tube.

4. A demand water heater as claimed in claim 1 in which the valve is of a seat and co-operating closure member type and the closure member is operable through a mechanical linkage movable by a operating member on the downstream side of the water heater.

5. A demand water heater as claimed in claim 4 in which the mechanical linkage is an axially movable flexible or rigid shaft, the shaft being movable by a tap spindle or the like.

6. A demand water heater as claimed in claim 5 in which the water heater is adapted to be connected directly to the screw threaded spigot of a pillar type of tap and the mechanical linkage is an extension rod connected to the tap spindle.

7. A demand water heater as claimed in any one of the preceeding claims in which the water heater comprises an electrical immersion heater element connected to a power input through a flow operated switching arrangement including a magnetically operated switch and an operating magnet in flow passage and movable between two positions corresponding to no flow in which condition the heating element is off, and flow greater than a predetermined minimum in which the heating element is in an "on" condition.

8. A demand heater as claimed in claim 7 in which the heating chamber is of a tubular construction with the electrical immersion heating element extending longitudinally within the tubular heating chamber.

9. A demand water heater as claimed in any one of claims 1 to 6 in which the water heater has a gas burner assembly for effecting heating of the water and a flow operated diaphragm valve is embodied in the assembly and is adapted to be operated by flow through the heater.

10. A demand water heater as claimed in any one of the preceeding claims in which the outlet from the heating chamber is located such that in the operative orientation of the heater, the heating chamber remains full of water when the valve is closed.

11. A demand water heater as claimed in claim 1 and substantially as herein described or as emphasised with reference to Figures 2 and 3, Figures 4 and 5 or Figure 6 of the accompanying drawings.