FORM-2
THE PATENTS ACT,1970
COMPLETE SPECIFICATION
(SECTION -10)
A domestic storage water heater with an arrangement; means of achieving faster heating of water.
BAJAJ ELECTRICALS LIMITED, a company incorporated under the Indian Companies Act, 1956, having its registered office at 45/47, Veer IMariman Road, Mumbai-400 001, Maharashtra, India.
AN INDIAN COMPANY
The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed: -

TECHNICAL FIELD:
In the context of below description, it is important to define and specify two distinct types of water heaters available in market.
One of the two types of water heaters available is storage water heaters, which are popular since they provide large volumes of hot water during use. Two or more users can use water for bathing thus eliminating the need for heating water every time it is required for use. However the initial heating of the water takes approximately 40 minutes for 25L storage water heater; which is substantial.
Other type is Instant water heaters which quickly delivers hot water; however they give small quantity of water; i.e flow rate of water is low.
The present invention, identified by the applicant with the term and expression RAPIDOTHERM, intends to shorten the time required for heating water in conventional domestic storage water heaters. The regular capacities of storage water heaters in market are 10 litres, 15 litres, 25 litres, 35 litres, 50 litres and 100 litres. The water heaters comprise of storage tank made of typically copper, stainless steel or enamelled mild steel. The nickel chromium (NiCr) heating element with copper sheath (sometimes SS / Incolloy sheath is also used) usually is mounted on a plate hereinafter referred to as "apparatus plate" such that this apparatus plate is covering the mouth of the enclosed tank with water tight seal. The tank has two connected pipes for water entry and water exit referred as "inlet pipe" and "outlet pipe". The outlet pipe is located such that the tank is always full of water to such a height that the heating element is always submersed in water. When electric supply is given to heating element, it

heats up and transmits heat energy to adjacent water. The water gets warm and then transmits heat through water by conduction and convection principles. The usual 2 KW heating element takes approximately 40 minutes to heat 25 L water to 70°C at outlet pipe. A provision by means of thermostat is given to ensure that electric supply to the heating element is controlled such that the temperature of water inside is maintained at range of 70°C -75°C. Additional protection is given for safety (in case of thermostat failure) by means of thermal cut out which disconnects power supply to heating element if water temperature reaches 92°C to 98°C.
Since the storage type water heaters need large amount of time for heating, it becomes necessary for the users to wait till water is heated and this is perceived to be a'lengthy and unnecessary wait by users. The proposed invention claims of an arrangement called Rapidotherm used in storage water heaters which offers quick heating and delivery of hot water at the outlet pipe.
BACKGROUND ART:
Standard Existing configuration and the working principle involved in standard existing product: see fig 1
The standard existing configuration consists of a tank containing water. The tank has an opening at one end and is closed by means of apparatus plate. The apparatus plate is affixed to the tank such that the fitting is water tight. Mounted on apparatus plate are heating element and thermostat and thermal cutout pockets. Through these pockets the probes of thermostat and cutout are mounted. The heating element is connected to the main supply through

thermostat and thermal cutout in series circuits. The tank has two pipes welded to itself or to apparatus plate. One of these pipes is inlet pipe while other is outlet pipe. Inlet pipe has a pressure release valve at entry which also acts as a non return valve. The outlet pipe is longer and is extended almost to the top of the tank. The water level in the tank is maintained till the top end of the outlet pipe from where hot water is discharged. The inlet pipe and outlet pipe are usually connected by hose to inlet valve and outlet valve in bathrooms. Both these valves are manually controlled valves.
Typically the entire tank assembly is mounted in outer body separated by means of insulation like glass wool or polyurethane foam. The two ends of the body are covered by top cover and bottom cover.
When inlet water is allowed to enter storage water heater, it starts filling inside the tank. The water level in tank increases til! it reaches the outlet pipe top end. Once the tank is filled completely, this outlet valve is closed.
When the electric supply to the storage water heater is switched ON, the heating element is subjected to 230V AC supply. The heating element heats up inside the water and starts dissipating heat to water. The heat is transferred to the surrounding water by means of conduction and convection. Since hot water moves upwards due to convection, hot water starts collecting on top region of the water column in tank. Slowly the entire water in tank heats up. Once the temperature of water reaches the value set for upper limit of thermostat, it disconnects the power supply to heating element. The outer insulating material ensures that the heat of water inside is not lost due to conduction to atmosphere. Still there is some heat loss owing to which the temperature of

water in tank slowly drops. Similarly, when the hot water is discharged from outlet pipe, cold water enters the tank. This results in drop in temperature of water in tank. When the temperature of water drops below the value of thermostat setting, the thermostat switches ON the power supply to heating element, thus initiating the heating of water again. Thus the temperature of water in the tank is maintained in the range of 70°C -75°C.
Refer fig 1; the temperature distribution of a typical tank is shown in the figure on leftside.
OBJECT OF THE INVENTION :
The object of the present invention is to provide to the user hot water for use
faster than current time taken by conventional storage water heaters.
This is achieved by having Rapidotherm arrangement inside the storage water
heater.
SUMMARY OF THE INVENTION:
Construction: -
The invention enables the control of the heat within the tank such that hot water is quickly available at outlet for use in less time than conventional storage water heater. Please refer figure 2

The proposed invention is a storage water heater with a tank containing water. The tank is having opening at one end. At the tank opening, an apparatus plate is mounted water tight with help of bolts and screws and rubber gasket. Heating element is attached on the apparatus plate. Two pockets for thermostat and thermal cut out are also mounted on apparatus plate. The thermostat and thermal cut out are set to maintain water temperature in range of 70°C-75°C and 92°C -98°C respectively.
Surrounding the heating element and thermostat / thermal cut out pockets, a perforated central shell is mounted on apparatus plate. The perforated central shell is made of stainless steel. The length of the perforated central shell is such that it is few millimeters below the water outlet. The diameter of the central shell is such that it encloses heating element and thermostat / thermal cutout completely. Under normal working conditions, the perforated central shell is immersed in water entirely.
Two pipes for inlet and outlet of water are mounted on tank with watertight welding. The inlet pipe has pressure release valve at its inlet and is shorter in length. The outlet pipe is long and its top end inside the tank defines the water level inside the tank. It is extended almost up to 90% of tank height.
Outside the water heater the inlet side of the pipe is connected to loft tank or main water supply by flexible hoses. The outlet side is connected to a valve of a tap or water mixer or shower.
The tank and assembly of all these components is mounted inside the outer body. The gap between the outer body and tank is filled with insulating material (usually polyurethane foam or glass wool). This insulating material helps to maintain water temperature inside the tank.

The outer body is mounted on wall or floor by means of brackets attached to it externally.
The heating element is connected to the electric mains wire through thermostat and thermal cutout in series circuits.
Working principle of RAPIDOTHERM
Initially, water fills inside the water heater till it reaches outlet pipe. If the outlet side valve is in flow condition or open, the water flows through. For heating water, the valve is in closed position.
When the electric supply is switched on, the heating element starts heating the surrounding water. The heat propagates through water volume by conduction and convection. The perforated central shell encloses certain mass of water. Initially since the perforated central shell separates the water volume, more heat transfer happens within the central shell than its outside. However through the perforations, the water molecules transfer heat. Along the large surface area of the central perforated shell, significantly small area is open to outside water volume. Hence the water inside the shell heats up rapidly than the water outside the shell.
Due to convection heat transfer, the hot water rises towards top and is replaced by cold water outside the shell. This outside water enters shell through perforations at bottom causing turbulent flow. This enables further mixing of hot and cold water inside central perforated shell.

The result of the above heating cycle is mapped with the temperature gradient of water inside shell as compared to the same of water outside the shell. Please refer figure 3.
Since small quantity of water is heated in perforated shell, it heats up rapidly. When hot water rises in central shell, it is discharged at top end, very near the top outlet. The outlet pipe collects it and discharges it through outlet system when outlet valve is opened.
The time required for the water temperature at outlet for two systems is mapped as per graph 1 below as Figure 4.
It needs to be noted, that, though the heating is rapid at central shell, it has reduced at the farther corners inside the water tank. Overall it takes same amount of power to heat water.
However the only change is that the hot water is quickly available at outlet even before the first thermostat cut off. Thus User will always get hotter water quickly with rapidotherm arrangement.

Claims:
We claim
1. A storage water heater with a rapidotherm arrangement and assembly such that the outer body of the water heater consists within a tank containing water having an opening at one end wherefrom is mounted an apparatus plate assembled water tight consisting of heating element, thermostat pocket, thermal cut out pocket and a central stainless steel perforated shell all mounted on the apparatus plate besides having an inlet pipe for inflow of water and a longer outlet pipe for water to flow out, both regulated by valves with the top end of the long outlet pipe defining the water level inside the tank.
2. An invention as claimed in claim 1 above, where the length of the central perforated shell is such that it is few millimeters below the water outlet with the diameter of the central shell encompassing within it the heating element and thermostat / thermal cutout completely, all of which are immersed in water.
3. An invention as claimed in claims 1 and 2 above which works on the principle of Rapidotherm having a construction as mentioned in claim 2 above, such that water is first filled in the tank with the electric supply switched on and the heating element heats the surrounding water within the perforated central shell rapidly as compared to the water outside the central shell and the heat thus generated in the water present within the central shell propagates by convection and rises on top of the central shell and is replaced by water entering the bottom of the central shell through its perforations causing a turbulent flow; with the hot water getting discharged at the top end of the

central shell very near the top outlet pipe which inturn collects it and discharges it through the outlet system when the outlet valve is opened.
4. An invention as claimed in claims 2 and 3 above wherein the heating of water is rapid within the perforated central shell and is comparable reduced at the farther corners inside the water tank, though taking same amount of power to heat water.
5. An invention as claimed in claims 2 and 3 above wherein hot water within the perforated central shell is rapidly heated and the hot water is quickly available at the outlet even before the first thermostat cuts off.
6. An invention which consists of a perforated central shell which surrounds the heating element and thermostat and thermal cut out pockets and extends in height till almost the total water level inside the tank just below the water outlet pipe; the entire assembly referred to and working on the principle of Rapidotherm.
7. An invention wherein using the Rapidotherm arrangement and assembly, water inside the central perforated shell heats up rapidly such that hot water rises rapidly inside the central perforated shell and is quickly delivered at the outlet water pipe level; thus meriting the user for he gets to use continuous stream of hot water quickly as compared to conventional storage water heaters available in market at any time during heating period.
8. An invention relating to the assembly used in storage water heaters with varying capacities as claimed in claim 2 above which can be used in different

orientations like wall mounting, floor mounting and vertical mounting storage water heaters.