FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION
A fluid heater with dry heating protection system
APPLICANTS :
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S):
Nadkarni Mayur of Crompton Greaves Limited Appliances Division, Crompton Greaves Limited, Kanjur Marg (E), Mumbai - 400042, Maharashtra, India; all Indian Nationals.
PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

Field of the Invention:
This invention relates to the field of electrical and electronic appliances, Particularly, this invention relates to the field of water heaters and water boilers.
More particularly, this invention relates to a fluid heater with dry heating protection system.
Background of the Invention:
Water heaters, used for home use, or for commercial use, comprise a water tank. Typically, this water tank is an insulated water tank. The water tank is electrically heated in order to heat the water inside the tank either by convection. The heating may be means of internally placed or peripherally placed heating elements.
A thermostat is provided to provide automatic heat control so that water does not cross intended heating temperatures and so that the water heater is safely operated. Inlet pipes and outlet pipes are provided for inlet and outlet purposes. Flow delivery of the water into the water heater and out of the water heater is controlled by valves.
A typical storage water heater works on the principle of displacement i.e. the heated water comes out of the outlet pipe, provided there is availability of water at inlet pipe. However, in absence of water inlet if the heater is switched ON, there are chances that heated water may get evaporated and can expose the heating element to air (due to lack of water). This heating element would then be subjected

to 'dry heating' which is an undesirable condition for the healthy working of the heating element, in particular, and for the heater, in general.
This results in a potentially hazardous situation and consequently results into user dissatisfaction with respect to the heater product.
Hence, there is a need for an improved water heater which obviates these concerns.
Objects of the invention:
An object of invention is to eliminate the chances of dry heating by usage of inbuilt protection system.
Another object of the invention is to provide a safe and fail-proof water heater.
Yet another object of the invention is to sense the condition of 'dry heating' before the heater element of a heater is engaged.
Still another object of the invention is to operate a heater only when there is no condition of 'dry-heating'.
An additional object of the invention is to provide a sensing mechanism to sense 'dry heating' which sensing mechanism is not in direct communication with the fluid of the heater.
Yet an additional object of the invention is to provide a sensing mechanism and water heater which is a relatively simpler assembly.

Summary of the Invention:
According to this invention, there is provided a fluid heater with dry heating protection system, said heater having a tank to hold said fluid to be heated by means of a heating element powered by an electrical connection, the temperature of said fluid being governed by thermostat and a thermal cut-out element adapted to cut-off said electrical connection to said heating element in correlation with said thermostat characteristics; an inlet pipe to allow inlet of fluid into said tank; an outlet pipe to allow outlet of fluid from said tank; characterised in that, said heater controller by a dry heating protection system, said system comprising:
a. pressure sensor adapted to adapted to sense pressure of air (volume not
covered by fluid) in said fluid heater; and
b. pressure switch adapted to electrically connect said heater element to said
electrical connection in accordance with pre-defined sensed pressure.
Typically, said tank is a thermally insulated tank
Typically, said system includes a contact switch adapted to control electrical connection to said heater element.
Typically, said system includes a controller means adapted to receive thermostat input and pressure input and further adapted to control electrical connection to said heater element in correlation with pre-defined parameters selected from a group of parameters consisting of temperature parameters, pressure parameters, and their correlation.
Typically said pressure switch is ensconced within walls of said tank.

Typically, said pressure switch is connected to said inlet pipe.
Brief Description of the Accompanying Drawings:
Figure la illustrates a schematic of the water heater of the prior art; and
Figure lb illustrates a wire diagram of the operation of the water heater of Figure la.
The invention will now be described in relation to the accompanying drawings, in which:
Figure 2a illustrates a schematic of the water heater; and
Figure 2b illustrates a wire diagram of the operation of the water heater of Figure la.
Detailed Description of the Accompanying Drawings:
Although, the specification below, is explained in relation to a * water heater', it is to be understood that water may be replaced with any fluid and the water heater may thus be generalised to be called a fluid heater, depending upon its use.
Figure la illustrates a schematic of the water heater of the prior art.
A typical construction of the water heater (100) is illustrated in Figure la. As can be seen, water enters the water heater (100) from an inlet pipe (12) and gets stored in the tank (14) till the brink of outlet pipe (16). Once the water heater is switched ON, the heating element (18) gets power supply and starts heating the water (20).

The temperature of heated water is sensed by a thermostat (22) which cuts off the supply to the heating element (18) by means of a control circuit, when the desired temperature is reached. Here, there is no correlation between the switching of water heater (100) and availability of water (20) inside the tank (14).
As explained earlier, due to displacement principle, the hot water comes out of outlet pipe (16) when turned ON, provided there is availability of water (20) in the inlet pipe (12).
In case there is no inlet water and the water heater (100) is switched ON, then there are chances that the existing water available in the tank would get heated and subsequently get evaporated over a period of time. This would expose the heating element (18) in air and would be subjected to dry heating leading to the failure of the heating element and the heater. As such the water heater would not heat the water due to failure of heating element.
Reference numeral 24 refers to thermal insulation of the water heater (100). Reference numeral 26 refers to outlet flexible pipe. Reference numeral 28 refers to inlet flexible pipe. Reference numeral 30 refers to multi-function valve of the input pipe. Reference numeral 32 refers to thermal cut-out element.
Figure lb illustrates a wire diagram of the operation of the water heater of Figure la. Reference numeral 34 refers to indicative light 1 and reference numeral 36 refers to indicative light 2.
According to this invention, there is provided a fluid heater with dry heating protection system.

Figure 2a illustrates a schematic of the water heater (200).
Figure 2b illustrates a wire diagram of the operation of the water heater (200) of Figure 2a.
In this system, an inbuilt dry heat protection system has been incorporated in which the heating element would get ON only if there is enough availability of water inside the tank.
The basic construction of the tank and its inlet outlet pipes is the same as the construction explained in reference to Figure la of the accompanying drawings, above.
In accordance with an embodiment of this invention, there is provided pressure sensor (50) adapted to sense pressure of air in said water heater. A pressure switch works on the principle of pressure generated inside the rubber (pressure switch) pipe connecting between the pressure switch and inlet pipe (12).
In accordance with another embodiment of this invention, there is provided a pressure switch (not shown) which makes an electrical contact (not shown) upon sensing pre-defined pressure by said pressure switch. A pressure switch has two connectors which get connected by a diaphragm which gets pushed towards it when enough (pre-defined) air pressure gets generated. These connectors are connected in series with the heating element (18). When there is availability of water (20) inside the tank (14), the air pressure generated in the rubber pipe would be high and that would close the contacts of pressure switch and thus heating element (18) can get ON if the water heater is switched ON.

In the event that there is no availability of inlet water (20) and water heater (200) is switched ON, the water (20) already available in the tank (14) would start heating and would slowly start evaporating. This would lower the water level inside the tank (14) as well as disengage the pressure switch, thus releasing the air pressure inside the pressure switch. This would cause the contacts to get open at a pre¬defined pressure. This would break the power supply to heating element (18) and water (20) would stop heating further. This would ensure that heating element (18) would be always in contact with water (20) so that there are no chances of it getting exposed to air and of dry-heating.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1. A fluid heater with dry heating protection system, said heater having a tank to
hold said fluid to be heated by means of a heating element powered by an
electrical connection, the temperature of said fluid being governed by
thermostat and a thermal cut-out element adapted to cut-off said electrical
connection to said heating element in correlation with said thermostat
characteristics; an inlet pipe to allow inlet of fluid into said tank; an outlet pipe
to allow outlet of fluid from said tank; characterised in that, said heater
controller by a dry heating protection system, said system comprising:
a. pressure sensor adapted to adapted to sense pressure of air (volume not
covered by fluid) in said fluid heater; and
b. pressure switch adapted to electrically connect said heater element to said
electrical connection in accordance with pre-defined sensed pressure.
2. A fluid heater with dry heating protection system as claimed in claim 1 wherein, said tank is a thermally insulated tank
3. A fluid heater with dry heating protection system as claimed in claim 1 wherein, said system includes a contact switch adapted to control electrical connection to said heater element.
4. A fluid heater with dry heating protection system as claimed in claim 1 wherein, said system includes a controller means adapted to receive thermostat input and pressure input and further adapted to control electrical connection to said heater element in correlation with pre-defined parameters selected from a

group of parameters consisting of temperature parameters, pressure parameters, and their correlation.
5. A fluid heater with dry heating protection system as claimed in claim 1 wherein, said pressure switch is ensconced within walls of said tank.
6. A fluid heater with dry heating protection system as claimed in claim 1 wherein, said pressure switch is connected to said inlet pipe.