WO2010004380A2

WO2010004380A2 - Integrated heating device for storage water heater

Info

Publication number: WO2010004380A2
Application number: PCT/IB2009/005701
Authority: WO
Inventors: Claudio Capitanelli
Original assignee: Thermowatt SpA
Current assignee: Thermowatt SpA
Priority date: 2008-07-11
Filing date: 2009-05-19
Publication date: 2010-01-14
Anticipated expiration: 2011-01-11
Also published as: CN102216693A; WO2010004380A3; RU2011105070A; ITAN20080017U1; RU2519115C2

Abstract

The present invention refers to a supplementary heating device for a storage water heater (8) which is designed to be located inside a water heater and is designed to heat the water drawn from the tank (1) only when needed.

Description

INTEGRATED HEATING DEVICE FOR STORAGE WATER HEATER

DESCRIPTION

The present patent relates to a supplementary heater element able to improve the performance of water heaters, particularly storage water heaters. The invention is therefore part of the sector of sanitary water heating by means of electricity, a sector in which there are currently two types of apparatus: storage water heaters and instantaneous water heaters, each of which has its specific advantages and disadvantages.

Storage water heaters have the advantage of distributing large quantities of water at a preset temperature, thereby concurrently meeting the hot water requirement of many users while using a relatively small amount of power (for example, 1200 W for the most common models used in Italy).

It is very simple to regulate the temperature of the water supplied with these appliances, no matter what the flow, either by a thermostatic mixer or simply by turning the knobs of the faucets. However, there is also a disadvantage in that it takes many hours to replenish the amount of hot water contained in the storage tank; in addition, these water heaters are subjected to great amounts of heat loss, in spite of the presence of insulating material on the walls of the tank.

The instantaneous water heaters have the advantage of instantaneously supplying water at the desired temperature and without limits to quantities, by heating the water only as it is required by the user.

The disadvantage is that it uses quite high power levels, even to meet the needs of The disadvantage is that it uses quite high power levels, even to meet the needs of one user at a time.

Another disadvantage is the greater difficulty in regulating the temperature when lower flows of water, in respect of the maximum ones, are required, which can be achieved only with a prompt adjustment of the heating power; in the case of electric instantaneous water heaters, whose power can be easily around 10 kW or even 20 kW for a domestic water heater, it is difficult to obtain the on-off of the electric resistance without causing radio interference or power surges. Experts in the sector have long been familiar with the types of water heaters and the related abovementioned characteristics, therefore, it is not necessary to spend extra time on a detailed description.

In essence, the constituent elements of an electric storage water heater comprise a tank and a flange on which the heating elements are mounted (generally sheathed heating elements), the temperature control means of the accumulated water (generally a thermostat with one or more temperature sensors), inlet and outlet pipes (respectively for cold water from the mains and hot water to the user), and necessary safety and corrosion protection means (such as magnesium anode or electrode for cathode protection). Cold water flows into the tank through an inlet pipe at the bottom of the water heater, while the heated accumulated water is drawn out of the top of the tank through the outlet pipe.

Over the years, attempts have been made to obviate the most common problems regarding storage water heaters currently known, one of which consists in the loss of heat caused by a high temperature gradient present in the tank, hi fact, average temperatures and accumulated heat energy being equal, higher temperature gradients cause a greater loss of heat and higher energy consumption.

To make the temperature inside the water heater more uniform, the water is generally heated in the lower part of the tank, reducing the height of the resistances by bending them onto themselves. Said objective is reached by the application for Italian patent no. AN2004A000009, which makes it possible, besides the reduction of the mixing inconveniences, raising the average temperature, increasing the quantity of water that can be distributed at the correct temperature of use.

Naturally, an obvious way to limit heat loss is to maintain the temperature of the accumulated water as low as possible, heating it only when it is required, but another difficulty, inherent in that type of water heaters with sheathed heating elements, lies in the difficulty in the final heating of the water at the moment of the drawing. This difficulty was partly addressed with the inventions described in the two Italian patents owned by the applicant for the present patent. Italian patent no. 1315636 deals with, inter alia, an electric resistance printed on the outlet pipe, designed to complete the heating of the water delivered as the water is required by the user. The disadvantage of this invention is that in the drawing phase, not all the heat produced by the printed electric resistance is transferred to the delivered water but part is also transferred to the water remaining in the storage tank. Italian patent no. 1345037 also includes an accessory kit, mounted on the outside of the storage tank, which acts as a post-heater, being also designed to increase the temperature of the water delivered to the user at the moment of the drawing. The difficulty of this solution lies in the addition cost necessary to buy and install the accessory kit. The object of this invention is to eliminate at least part of the difficulties above, to develop a device that makes it possible to combine the advantages of storage water heaters with instantaneous water heaters, while limiting the respective disadvantages. Specifically, the purpose of the present invention is to identify a device that makes it possible to reduce the temperature of the water contained in the storage water heater with the resulting decrease in the heat lost, therefore ensuring the user the same performance of a traditional storage water heater, delivering the water at the desired temperature only when actually needed.

These and other objects, which will be clear subsequently, are achieved with a supplementary heating device, located inside the tank, according to Claim 1. Additional characteristics of the present invention will be better identified by the following description of a preferred embodiment, according to the patent claims and, by way of example and not limited to, illustrated in the appended drawings, in which: figure 1 is a cross section view of the tank of a storage water heater, including the supplementary heating device according to the invention; figure 2 is a perspective view of the flange of the storage water heater, which mounted inside the supplementary heating device according to the invention; figure 3 is a cross section view of the supplementary heating device according to the invention.

We are now describing the characteristics of the invention, using the numbered references in the drawings.

With reference to figure 1, the number 1 indicates the tank of an electrical storage water heater, equipped with flange 2 designed to close the lower opening of the said tank l.

Flange 2 supports a sheath 3. a of a thermostat 3, designed to regulate the heating of the water accumulated in tank 1. The thermostat 3 can be a rod-type, as shown in the appended drawings. Alternatively, regulation of the temperature of the accumulated water in tank 1 can be achieved with an electrical and mechanical heat regulator or an electronic regulator of any known type.

The number 4 indicates an electric resistance for heating the water accumulated in tank 1. The water is introduced cold into the bottom of tank 1 by means of a first cold water inlet pipe 5, having an outlet end in correspondence to the bottom of tank 1 and water is drawn out near the top of tank 1 by means of a second pipe 6, having an inlet end at the upper part of tank 1.

The second pipe 6 runs essentially in parallel with the walls of tank 1 and ends with a lower end 6.d which powers the supplementary heating device 8 located inside the water heater. The second pipe therefore performs the function of a flow pipe for this supplementary heating device 8, which has a chamber 8. a, preferably of an elongated shape.

The second pipe 6 has a lower end section 6.c that crosses most of the chamber 8.a and terminates with an outlet end 6.d pointed toward the lower extremity of the chamber 8. a.

In the embodiment illustrated, the chamber 8.a is created inside a vessel 8.b which represents, practically, the envelope of the supplementary heating device 8. From the chamber 8. a, the water withdrawn exits through a third pipe 7 which has an initial upper section 7.b which crosses most of the chamber 8.a and has an inlet end 7.a pointed toward the top part of the chamber 8. a. The third pipe 7 performs the function of a flow pipe for the chamber 8.a.

Inside the chamber 8.a there is also an electric resistance 9, preferably in either a serpentine or coil shape, which heats the water that crosses the chamber 8. a. The electric resistance 9 is activated, at the moment of the drawing, by a flow sensor device 10.

The outlet end 6.d of the second pipe 6 and the inlet end 7.a of the third pipe 7 are arranged so as to maximize the amount of time the water remains in the chamber 8. a and the resulting heating of this water by the electric resistance 9. To summarize, the water drawn as required by the user must cross the chamber 8. a which, in turn, is connected to the tank 1 only through the pipe 6 and with the exterior only through the third pipe 7.

As a result, outwardly the storage water heater according to the invention is completely identical to other storage water heaters designed and known; in particular, the hydraulic connections at the water inlet and outlet can be identical and in the same usual positions.

In the examples of the drawings, the chamber 8. a of the supplementary heating device 8, object of the present invention, is the cavity of an envelope made up of a vessel 8.b, supported by the flange 2 which acts as the bottom surface. The vessel 8.b is welded to the second pipe 6 or connected by another means of attachment.

The third pipe 7 includes a section 7.c external to the water heater and a section 7.b inside of the chamber 8. a, which terminates with the upper hole 7.a, located in the top of the chamber 8. a. Therefore, according to the embodiment illustrated, the water delivered to the user first runs from the bottom to the top of the said chamber 8.a, lapping the electric resistance 9 which, in the case in point, is in a serpentine shape that surrounds this lower section 6.c of the second pipe 6 and the said internal section 7.b of the third pipe 7. Thanks to the supplementary heating device 8, it is possible to maintain the accumulated water in tank 1 at a temperature lower than the temperature desired by the user, as the supplementary heating device 8 carries out the process of heating the water to the usage temperature only when the water is required. For the purpose, the activation of serpentine-shaped electric resistance 9 of the supplementary heating device 8 is controlled by a flow sensor device, such as a flow switch or pressure switch, as the water is drawn out. Number 10 identifies this flow sensor device which, besides to activate the serpentine-shaped electric resistance 9 of the supplementary heating device 8, can also simultaneously deactivate the resistance 4 of the storage, acting on a switch not shown in the figures, to avoid excessive energy consumption.

An advantage of the supplementary heating device 8 is that it makes possible to build a storage water heater, in which the usual electric resistance 4 preheats the water accumulated in the tank 1 to a maintenance temperature lower than the temperature required by the user, while the usage temperature is reached only at the time of delivery, where the additional heat is provided by the supplementary heating device 8. As a result, energy consumptions are limited and heat losses inside the tank are reduced thanks to the lower temperature of the water accumulated in the tank, on par with the temperature of the water distributed. By way of example, if the user wanted the water to be delivered at 40 °C and it was heated in the storage only to 35 °C, the heat loss to a room temperature of 20 °C would be reduced by 25%.

By the same token, the power necessary to raise the water temperature at washbasin from 35 ⁰C to 40 °C is approximately 2 kW.

Furthermore, at a lower maintenance temperature of the water accumulated in the tank 1 corresponds a slower accumulation of lime; at the same time, inside the supplementary heating device 8, in which the water temperature never exceeds 55 °C, the risk that lime will build up is fairly low.

It is clear that a number of variations of the device object of the invention are possible for those skilled in the art without departing from the innovative concepts inherent in the invention and it is clear that, in the practical implementation of the invention, the various components described above may be replaced by technically equivalent elements.

For example, an electric storage water heater has been always described in the description, but nothing prevents that the same teachings can be applied to a gas- fired storage water heater in which the means of heating the accumulated water are represented by a gas burner instead of by one or more electric resistances.

In the same way, it is also clear that the vessel 8.b can be constructed in any material suitable to act as an envelope of the supplementary heating device 8, such as metal, plastic, foam or insulating material. In one variation of the invention, there might also be the possibility of using a safety thermoprotector to keep under control the temperature of the serpentine-shaped electric resistance 9 of the supplementary heating device 8, in order to avoid reaching excessive temperatures that could cause the water to boil, with the resulting noise. Furthermore, it might also include devices, not shown in the figures, associated with this flow sensor device 10 that, while withdrawing water, also adjust the power of resistance 9, using known means, to control the temperature and bring the water delivered to a preset usage temperature. Since the electric power of resistance 9 is approximately 20% of that of an instantaneous water heater of equal performance, it can be adjusted without difficulty.

Claims

C L A I M S

1. Supplementary heating device (8) to heat the water accumulated in the tank (1) of a storage water heater, said device (8) being designed to be located inside said tank (1) and comprising: a chamber (8.a);

- an inflow pipe (6; 6.c) into said chamber (8. a);

- an outflow pipe (7; 7.b) out of said chamber (8.a);

- an electric resistance (9) lodged inside said chamber (8. a), said electric resistance (9) being controlled at the time water is required by a flow sensor device (10).

2. Supplementary heating device (8) according to claim 1, in which said inflow pipe (6) has a lower section (6.c) having an outlet end (6.a) pointed toward the bottom of said chamber (8. a) and said outflow pipe (7) has an upper section (6.c) having an outlet end (7.a) pointed toward the top of said chamber (8.a).

3. Supplementary heating device (8) according to the claims 1 or 2, characterized in the fact of being united to a flange (2) of a storage water heater.

4. Supplementary heating device (8) according to any one of the previous claims, characterized in that said electric resistance (9) surrounds in a serpentine shape said lower section

(6.c) of said inflow pipe (6) and said upper section (7.b) of said outflow pipe (7).

5. Supplementary heating device (8) according to any one of the previous claims, characterized in that devices to regulate the power supplied by said electric resistance (9) of the said supplementary heating device (8) are foreseen, said regulating devices being associated with the flow sensor device (10) and being able to bring the usage temperature of the water to a preset value.

6. Supplementary heating device (8) according to any one of the previous claims, characterized in that the use of a safety thermoprotector to maintain under control the temperature of the electric resistance (9) of the said supplementary heating device (8) is foreseen.

7. Storage water heater, comprising: - a storage tank (1),

- heating devices (4) of the accumulated water in said tank (1),

- regulating device (3) of the temperature of the water accumulated in said tank (1).

- an inlet pipe (5) of the cold water having an outlet end in the lower part of said tank (1), an outlet pipe (6, 7) of the hot water to the user, characterized in that it has an additional supplementary heating device (8) according to one or more of the claims from 1 to 6.

8. Storage water heater according to the previous claim, characterized in that the flow sensor device (10), besides to activate the electric resistance (9) of said supplementary heating device (8), is able to disengage simultaneously the heating devices (4) of the accumulated water by a switch.