EP0324881B1

EP0324881B1 - Household water heater

Info

Publication number: EP0324881B1
Application number: EP19880100858
Authority: EP
Inventors: Abdul Aziz Abdullah Al-Saleh
Original assignee: Individual
Current assignee: Al-Saleh Abdul Aziz Abdullah
Priority date: 1988-01-21
Filing date: 1988-01-21
Publication date: 1992-09-09
Also published as: DE3874514D1; DE3874514T2; EP0324881A1

Description

The present invention relates to a household water heater according to the preamble of claim 1.

Technical background:

In some areas of the world, especially in those which are hot in summer and cold in winter, cooling and heating systems are installed in rooms separate from bathrooms and kitchens. In the latter, often a water heater is installed to heat water in winter, and when air heating is required, an additional heating system is installed.
The household water heater is a thermally insulated water storage tank enclosed in an outer shell operating by at least one heating element and fed from an electric supply, containing, besides, a thermostat and a safety valve.
For instance, the US patent 37 93 654 shows a combined space and water heating unit which basically comprises a hot water tank within an insulated enclosure. The enclosure includes a cool air entrance and a warm air exit whereby the latter is combined with a fan for circulating cool air coming from said entrance around the hot water tank to said outlet, where warm air is exhausted. Furthermore, the Swiss patent 154 745 shows a boiler which is mounted in a corner of two walls and which has an outer shell having a substantially cylindrical front side and flat rear sides, the latter being positioned in parallel to said walls.
The heating element consists of an electric resistant wire. The water container is cylindrical in order to resist steam pressure. The bottom and cover of the container are concave. At the bottom of the tank, there are tree holes, one for an inlet of cold water, the second for an outlet of hot water and the third for fixing the heating assembly as well as or cleaning the heater when it requires maintenance. The other shell of the heater is a steel cylinder welded to a cover and a base. At the base, there are two holes for cold and hot water passage. At the center of the base, there is a broad opening which has a separate cover screwed on that allows to check the heating unit, a thermostat and an indicating lamp. There also is a thermal insulating layer between the hot water tank and the exterior structure said layer being e.g. 3 cm thick. The indicating lamp can be connected in parallel with the heating unit and shall indicate the switching-on and switching-off of the electric current.
A safety valve is installed at the inlet of cold water that - in case of a damage of the thermostat - opens automatically when the steam pressure exceeds the setting value of the valve. A thermometer is installed to indicate the temperature of the water inside the heater. The heater is also provided with a metal support fixed to the exterior structure to allow the mounting of the heater without coming in contact with the wall.
The heater is usually used in bathrooms and kitchens for heating water only. It also occupies a large space due to its circular shape and, when it is installed, it will seem as a projection contacting with the wall and is not lined up with the surface of the wall. This will leave useless spaces at the sides and on the top in addition to hot and cold water and electric connections that are outside the heater, which makes the appearance irregular. Therefore, some attempts are made to cover the heater by placing it inside a drawer in the bathroom, in the skylight or on the roof. Sometimes, a central heating system is installed, but it is costy and requires a continuous hot water circulation system.

Disclosure of the present invention:

One object of the present invention is to avoid all defects resulting from the normal household water heater and to add other advantages. A further object of the present invention is to provide a household water heater that heats air to a required temperature as well. The solution of the present invention is stated in the characterizing part of claim 1. Improvements and further developments of the invention are disclosed in the subclaims.
A household water heater according to the invention comprises a substantially cylindrical hot water tank enclosed in a spaced insulating outer shell which has a substantially cylindrical front side and at least one flat rear side, the latter to be adjusted substantially in parallel to an adjacent wall or in a corner of two walls, so that extra spaces are left between said inner tank and said outer shell . Furthermore at least one of said extra spaces contains a substantially vertical air passage or channel contacting said hot water tank inside said outer shell; said air passage has a cold air inlet at the bottom and a hot air outlet at the top of the outer shell.
The new heater according to the present invention has two main functions; it heats water as well as air to a respective required temperature. It also occupies a small space and does not form a projection but seems to line up with the surface of the wall. All connections of hot and cold water as well as electricity can be hidden inside the heater. Above all, it is conforming to specifications. The water tank according to this invention, should be cylindrical and at both ends concave in order to resist to steam pressure.
Preferably, the outer shell of the heater can be constructed according to the following two designs corresponding to the side designated for installation:
In a first design, the outer shell will be a quarter cylinder that encloses a preferably cylindrical hot water tank. The cross section of the heater appears as a quarter circle enclosing a smaller full circle, which is the hot water tank.
This type is provided to be installed in a corner between two perpendicular walls. On both sides near the walls a considerably large extra space is left between the smaller circle and the outer shell.
In a second design, the outher shell or exterior structure of the heater is of a cylindrical shape a longitudinal segment of which is cut. This outer shell should enclose a preferably cylindrical hot water tank. The cross section of this heater appears as a circle, from which a segment or section is cut; this remainder of a circle encloses the smaller full circle characterizing the tank. Thus, in the second design again on both sides near the wall there is left a considerably large extra space between the inner circle and the outer shell.
The designs described above or the like realize the following advantages according to this invention:

(1) At the remaining space on both sides of the water tank, two passages for air heating can be installed so that they contact the hot water tank, preferably the passages are controlled in opening and closing by a thermostat in contact with the outer shell from inside. Preferably, the thermostat should be effected by the ambient (room) temperature and controlled to determine a pretended calorific effect, at which the heating passages open or close.
(2) Due to being a quarter of a cylinder in the first design, the outer shell conforms with the corner at which it is installed; and being a semicylinder in the second design, the outer shell conforms with the surface of a respective wall. Furthermore, the efficiency of the heater is improved if the outer heater shell touches the wall in its fixed position as little as possible.
The length of the heater according to the invention can be increased within the limits allowed by specifications and the area of the respective section can been decreased for the following purposes;
- a) reducing the area it occupies;
- b) reducing projection forward;
- c) to be installed so that its top will be in contact with the ceiling and not to leave any useless gaps around or on top of the heater;
- d) increasing the space between the inlet of cold air and the outlet of hot air which improves heating air circulation;
- e) increasing the length of air heating passage in contact with the hot water tank which increases the area of thermal radiation surface inside the passage consequently leading to the quick heating of the site.
When the heater is installed as mentioned above, it will appear as part of the site and will not show any exposed projection but it will seem to be lined up with the surface of the wall.
(3) The conformity of the heater with the surface of the wall will also enable to hide all external cold and hot water and electric connections inside a recess below the hot water tank. This advantage can be obtained by increasing the length of the outer shell by about 15 cm down to cover the external connections inside the heater in order to give it good appearance.

A water heater of the invention can be installed on the wall at a metal base fixed on the top of the wall adjacant to the ceiling.
Ways of performing the invention are described in detail below with reference to the drawings which illustrate specific embodiments, in which:

Fig. 1 is a perspective view of a first embodiment of a heater;
Fig. 2 is a perspective view of a second embodiment of a heater;
Fig. 3 shows a view of a bathroom with a heater installed;
Fig. 4 shows a cross section along the line IV - IV of Fig. 1;
Fig. 5 shows a cross section along the line V - V of Fig. 2;
Fig. 6 shows a view from the bottom of a heater mounted in a corner of two walls;
Fig. 7 shows a view from the bottom of a heater on a flat wall;
Fig. 8 shows a longitudinal section along the line VIII - VIII of Fig. 1;
Fig. 9 shows a type of fixing of the heater to a wall;
Fig. 10 and 11 show geometrical drawings for the calculating of two different types of heaters; and
Fig. 12 and 13 show other alternatives of the outer shell of the heater.

Fig. 1 shows a view of a heater 1 of a first design. The external structure of this heater is a quarter cylinder. The heater 1 is installed at a corner 2 between two perpendicular walls 3, 4. The full conformity with the surface of the wall can be seen as well as the top which is in contact with the ceiling (not shown). A hot air outlet appears as 5, thermometer 6, electric switch 7, indication lamp 8, control ON/OFF switch 9 and the external hot and cold water and electric connections are hidden inside the outer shell 10 of the heater 1.
Fig. 2 shows a view of a heater 11 of the second design. The exterior structure of this heater is a cylindrical outer shell 12, from which a longitudinal segment or strip 13 is cut. The heater 11 appears installed at the wall surface 14 and its top in contact with the ceiling. Similar to Fig. 1, the hot air outlet appears as 5. The thermometer 6, the electric switch 7, the indication lamp 8, the control ON/OFF switch 9 and the external hot and cold water and electric connections are hidden inside the outer shell 12 of the heater 11.
Fig. 3 shows the path 15 of air current in a bathroom, in which a heater 1 (or 11) is installed. The cold air 16 enters into the heating passage 17, 18 at the bottom 19 of the heater 1; inside the heater the air is heated; coming out through the outlet 5 the heated air forms a continuous air current 15. When the temperature of the bathroom reaches the required temperature, the air current 15 can be stopped by closing the heating passages 17, 18. The passages 17, 18 can be closed automatically by a heating thermostat which is effected by the ambient temperature only. In a similar way the passages 17, 18 can be opened when the room temperature decreases below a required threshold temperature.
Fig. 4 shows a section of the heater of Fig. 1 along the line IV - IV. The circle of the water tank 20 and air heating passages 17 und 18 are represented. A section of the thermostat appears as 21 at a point away from the heater tank 20 as far as a possible in order not to be effected by the heat emitted from the tank. It is noted that the outer shell 10 of the heater according to the present example is round at the rear side or back 22 and not square; this configuration helps to space the heater from the very corner and to decrease the quantity of insulation needed for the heater. Furthermore a rounded back 22 makes it easier to mount the heater in conformity with the surface of the wall, even if the angle of the corner is not fully square.
From the same Fig. 4, it is noted that there are projecting edges or shoulders 23 and 24, e.g. 2 cm wide, on both orders of the front sides. These projecting edges 23, 24 are provided to define a minimum distance between the heater, particularly its rear side and the surface of the wall 3, 4 as specified.
Fig. 5 shows a section of the heater 11 of Fig. 2 through the line V - V. The circle of the water tank 20 and air heating passages 17 and 18 are represented. This figure also shows a section of the thermostat 21. The projecting edges 23, 24, e.g. of about 2 cm wide on the front side of the heater are supposed again to keep distance between the heater 11 and the surface 14 of the wall as specified.
Fig. 6 and 7 show a view of the heaters 1 or 11 as shown in Fig. 1 and 2, particularly the bottom cover appears and air inlets 25 are visible. It is also noted that the heater 1 (or 11) does not come in an area contact with the adjacent surfaces of the walls 3, 4 or 14, respectively.
Fig. 8 is a section along the line VIII - VIII of Fig. 1, and shows the air passage 17, 18 within the heater 1 (or 11) where the temperature of the passing air 26 raises due to being passed along the hot water tank 20; the respective air flow 26 is maintained until the whole ambient room is heated to a required temperature. At that point, the passage is closed, e.g. by top covers 27 and 28, which are controlled by the thermostat 21. This Fig. 8 also shows two bottom covers 29 and 30. They can be manually closed from outside when a heating is not required. When these bottom covers 29 and 30 are closed, the top covers 27, 28 shall also be closed; preferably, they shall be closed automatically. Exterior hot water connections 31 and cold water connections 32 as well as electric connections 39 of a heating cartridge or the like are hidden inside the heater structure, say its outer shell, the bottom side of the latter is covered by a bottom cover 34.

Air heating method:

Cold air 16 enters through the bottom cover 34 of the heater, which covers the exterior connections but allows air intake; the air 26 is passed through the two passages 17, 18 where it contacts the hot water tank 20. The temperature of the circulating air 16 increases due to the contact with the hot surface of the hot water tank and to the thermal radiation which is emitted by the hot water tank 20. The inside of the passages 17, 18 shall be of a dark colour in order to emit as much heat as possible. The air rises when its temperature increases, and exits through the hot air outlet 5, which is situated at the top. When the outside room is heated up to the required temperature, the air passages 17, 18 shall be closed by the heat insulating covers 27, 28 at the top of Fig. 8, which are controlled by an inside thermostat 21 fixed at the outer shell 10 or 12 of the heater (see Fig. 4 and 5).
There is a heat insulating cover 29 or 30 at the bottom of the entrance of the air heating passages 17 and 18 of Fig. 8 as well. These covers 29, 30 may be manually closed by a switch 9 from the outside (see Fig. 1, 2) when the air heating function is not desired. The bottom covers 29, 30 are designed to prevent the thermostat from opening the top covers 27, 28 in Fig. 8, which avoids an undesired heat leakage from the heaters 1 or 11.
The heater of the present invention may be used as a heating system, in the area where it is installed, especially in regions where people use heating and cooling systems for rooms separate from those of kitchens and bathrooms, which provides cost savings. In the space at the bottom of the heater, a vertical barrier may be added to separate electrical connections in one side, and hot and cold water connections in the other.
In a preferred embodiment said outer shell 10, 12 at its lower end is constructed to form a recess at the bottom of the hot water tank 20, said recess hiding the outside connections 31, 32, 39 of cold and hot water as well as the electric connections and said cold air inlet 25. The idea of making the recess at the bottom of the hot water tank is that the recess will be particularly useful if the outside connections of hot and cold water and electric connections which come out of the wall, are installed in front of the recess during the construction of the building. Otherwise, the recess cannot cover the outside connections.
A "T" joint can be installed at cold water opening 35 (Fig. 8) in order to prevent the flow of cold water directly to the hot water opening at the top 40 without being heated and completely mixed with hot water.
To avoid an area contact between the heater and the adjacent wall surface, as per specification, the front side of the heater preferably shall be extended by e.g. 2 cm at both vertical and longitudinal edges (see Fig. 4 and 5). This extension defines a space between the rearside of the heater and the wall surface, if the longitudinal extension of the heater touches the wall.
A metal grill shelf coated with chrome or plastic for decoration plants or other light objects may be fixed at the lower part of the heater.
The fixing procedure of the present heater 11 (or 1) on the wall 3, 4 or 14 is easier and more accurate than that of the conventional heaters. It does not require any measurements or adjustments. The heater is set up above a fixing base 36 mounted up to the ceiling 37 as shown in Fig. 9 using a screw 38 at the bottom (see Fig. 9) in order to prevent any movement of the heater when pushed up, unless this screw is unscrewed.
If the heater was too high above ground level a small channel or chrome pipe of e.g. about 60 cm may be installed under the heater in order to serve as a cold air inlet; furthermore if occasion arises the other openings on the bottom cover of the heater shall be omitted, so that the distance between air inlet and outlet points is increased respectively, and accumulation of the hot air at the top and the cold air at the bottom is avoided. The length of such channel may be increased, and it may be installed inside the adjacent wall. A little fan may be fixed inside the heater to suck or push the heated air through the heating channel from the bottom to the top of the heater.
The present water heater which encloses a cylindrical hot water tank is used to heat the ambient air by passing it along the hot water tank. The cylindrical hot water tank is enclosed in an outer shell which is lined up with the surface of the respective adjacent wall so that on both sides of the tank extra spaces are left for the installation of vertical channels for passing the air to be heated along the surface of the hot water tank.
Thus an essential feature of the present invention is the combination of said lining up the outer shell with the surface of the wall on the one hand and the extra spaces on the other hand which are a rendt of the lining up. This means that said lining up the outer shell with the wall or walls constitutes a double function, that is: it not only improves the aesthetics of the heater but also - as a surprising effect - it furnishes the extra spaces (between the outer shell and the hot water tank) for a proper installation of vertical air heating channels.

Design of heater dimension (example)

First:

Water tank dimensions:
Required capacity: 30, 50, 80 and 100 litres
In case of a heater having a capacity or volume V of 80,000 cm³ for example:
The maximum allowed ratio between tank height h and diameter d or radius r as per specification is

$h ≦ 4 d$

The following ratio shall be used as an example

$h = 3 d = 6 r$
The water tank volume V is the product of the base area and the height h

Dimensions of the outer shell: An example

Height = H = 97,2 + 15 + 6 + 5 = 123 cm approx. whereby 15 cm is the space required for the connections of hot and cold water and electricity at the bottom of the heater;

6 cm: is the total thickness of the insulator at the top and bottom of the heater; and
5 cm: is the space required for the movement of the upper cover where hot air exits.

Radius (R) of the exterior Structure

(1) For the first design:

$R = 3 + r + (r + 3) √ \bar{2} = 3 + 16,2 + (16,2 + 3) √ \bar{2} = 46 cm approx. (Figure 10)$

3 cm = thickness of the insulator.
(2) For the second design:

$R = 3 + r + r / 3 = 3 x 16,2 + 16,2 / 3 = 24,6 cm approx (Fig. 11)$

Figs. 12 and 13 show other alternatives of the outer shell shape of the present heater. It can be similar to Fig. 4 and 5 but with corrugated outer shell 10 or 12 . Also the bottom cover can be with slope towards the wall.

Claims

A household water heater (1, 11) to be fixed to a wall (3, 4; 14), preferably at a metal base fixed on the top of the wall adjacent to the ceiling, said water heater comprising a substantially cylindrical hot water tank (20) enclosed in a spaced insulating outer shell (10, 12), which has a front side and at least one flat rear side (22) the latter to be adjusted substantially in parallel to the adjacent wall or walls (3, 4; 14), so that extra spaces are left between said inner tank (20) and said outer shell, whereas at least one of said extra spaces contains an air passage or channel (17, 18) contacting said hot water tank (20) inside said outer shell (10, 12), said air passage (17, 18) having a cold air inlet (25) and a hot air outlet (5) characterized in that
a) said front side is substantially cylindrical;

b) said air passage or channel (17, 18) is substantially vertical;

c) said cold air inlet (25) is at the bottom and said hot air outlet (5) is at the top of the outer shell (10, 12); and

d) each of said air passages (17, 18) has adjacent said hot air outlet (5) a cover (27, 28) which is controlled by a thermostat (21) and prevents or allows an air flow (26) and adjacent said cold air inlet (25) a cover (29, 30) which can be manually closed.
A water heater of claim 1,
characterized in that said thermostat (21) is connected to a device (9) detecting the ambient air temperature particularly a thermometer, and has means to preset a desired ambient air temperature.
A water heater of claim 1 to 2,
characterized by two spaced air passages (17, 18) each of which being in one of the extra spaces.
A water heater of claims 2 or 3,
characterized in that said device (g) detecting the ambient air temperature is mounted on said outer shell (20) at a point insulated and farthest possible from said hot water tank (20).
A water heater of one or more of claims 1 to 4,
characterized in that said outer shell (10, 12) at its upper end or top is constructed to be in contact with the ceiling of the room to be heated.
A water heater of one or more of claims 1 to 5,
characterized in that said outer shell (10, 12) at its lower end is constructed to form a recess at the bottom of the hot water tank (20), said recess hiding the outside connections (31, 32, 39) of cold and hot water as well as electric connections and said cold air inlet (25).
A water heater of one or more of claims 1 to 6,
characterized in that said outer shell (10) has a shape similar to a quarter cylinder or a corresponding corrugated form having two flat rear sides to be fit to the corner (2) of two walls (3, 4).
A water heater of one or more of claims 1 to 6,
characterized in that said outer shell (12) has a shape similar to a cylinder section or a corresponding corrugated form having one flat rear side (13) to be fit to one wall (14).
A water heater of claims 7 or 8,
characterized by each of said respective flat rear sides having at least one projection (23, 24), particularly formed as a shoulder, all along the vertical border of the whole of said one or two flat rear sides, said projection defining a heat insulating space - preferably closed - between said flat rear side or sides (13, 22) and said adjacent wall or walls (3, 4; 14).